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Reproduction, although absolutely essential to a species' persistence, is in itself challenging. As anthropogenic change increasingly affects every landscape on Earth, it is critical to understand how specific pressures impact the reproductive efforts of individuals, which directly contribute to the success or failure of populations. However, organisms rarely encounter a single burden at a time, and the interactions of environmental challenges can have compounding effects. Understanding environmental and physiological pressures is difficult because they are often context‐dependent and not generalizable, but long‐term monitoring across variable landscapes and weather patterns can improve our understanding of these complex interactions. We tested the effects of urbanization, climate, and individual condition on the reproductive investment of wild side‐blotched lizards (Uta stansburiana) by measuring physiological/reproductive metrics from six populations in urban and rural areas over six consecutive years of variable precipitation. We observed that reproductive stage affected body condition, corticosterone concentration, and oxidative stress. We also observed that reproductive patterns differed between urban and rural populations depending on rainfall, with rural animals increasing reproductive investment during rainier years compared to urban conspecifics, and that reproductive decisions appeared to occur early in the reproductive process. These results demonstrate the plastic nature of a generalist species optimizing lifetime fitness under varying conditions. [ABSTRACT FROM AUTHOR]

* Context.--Urinalysis instrument--specific dip strips offer physicians qualitative results for actionable analytes (protein, glucose, leukocyte esterase, nitrates, hemoglobin, and ketones). Objective.--To explain a strategy implemented to support clinical decision-making by providing urine quantification of protein, glucose, white blood cells (WBCs), and red blood cells because of urine strip shortages. Design.--During shortages, we implemented an automated algorithm that triggered sending urine samples to the automation line for quantification of protein and glucose and ensured that urine microscopy was performed to obtain WBC and red blood cell counts. The algorithm printed 2 labels so nursing staff would collect 2 specimens. We monitored the turnaround time from the specimen being received in the laboratory to result verification, ensured that the culture reflex order was triggered, and tracked complaints by physicians regarding not having usual urinalysis results. Prior to implementation, correlation between sample types for protein and glucose measurement was found acceptable. Results.--The algorithm was put in place twice during 2022. The turnaround time of urine microscopic study was identical to that obtained when the urinalysis was done with the strips; however, the quantification of glucose and protein took approximately 30 minutes more. Urine reflex cultures were triggered correctly with the algorithm, as they were derived entirely from a WBC count higher than 10 per high-power field. During the shortage period we had only 1 complaint, by a physician wanting to have results of nitrates. Conclusions.--During urine strip shortages, we successfully implemented a diversion algorithm that provided actionable urinalysis analytes in a timely manner with minimal provider complaints. [ABSTRACT FROM AUTHOR]

Background: We have been documenting the biological responses to low levels of radiation (natural background) and very low level radiation (below background), and thus these studies are testing mild external stimuli to which we would expect relatively mild biological responses. We recently published a transcriptome software comparison study based on RNA-Seqs from a below background radiation treatment of two model organisms, E. coli and C. elegans (Thawng and Smith, BMC Genomics 23:452, 2022). We reported DNAstar-D (Deseq2 in the DNAstar software pipeline) to be the more conservative, realistic tool for differential gene expression compared to other transcriptome software packages (CLC, Partek and DNAstar-E (using edgeR). Here we report two follow-up studies (one with a new model organism, Aedes aegypti and another software package (Azenta) on transcriptome responses from varying dose rates using three different sources of natural radiation. Results: When E. coli was exposed to varying levels of K40, we again found that the DNAstar-D pipeline yielded a more conservative number of DEGs and a lower fold-difference than the CLC pipeline and DNAstar-E run in parallel. After a 30 read minimum cutoff criterion was applied to the data, the number of significant DEGs ranged from 0 to 81 with DNAstar-D, while the number of significant DEGs ranged from 4 to 117 and 14 to 139 using DNAstar-E and the CLC pipelines, respectively. In terms of the extent of expression, the highest foldchange DEG was observed in DNAstar-E with 19.7-fold followed by 12.5-fold in CLC and 4.3-fold in DNAstar-D. In a recently completed study with Ae. Aegypti and using another software package (Azenta), we analyzed the RNA-Seq response to similar sources of low-level radiation and again found the DNAstar-D pipeline to give the more conservative number and fold-expression of DEGs compared to other softwares. The number of significant DEGs ranged 31–221 in Azenta and 31 to 237 in CLC, 19–252 in DNAstar-E and 0–67 in DNAStar-D. The highest fold-change of DEGs were found in CLC (1,350.9-fold), with DNAstar-E (5.9 -fold) and Azenta (5.5-fold) intermediate, and the lowest levels of expression (4-fold) found in DNAstar-D. Conclusions: This study once again highlights the importance of choosing appropriate software for transcriptome analysis. Using three different biological models (bacteria, nematode and mosquito) in four different studies testing very low levels of radiation (Van Voorhies et al., Front Public Health 8:581796, 2020; Thawng and Smith, BMC Genomics 23:452, 2022; current study), the CLC software package resulted in what appears to be an exaggerated gene expression response in terms of numbers of DEGs and extent of expression. Setting a 30-read cutoff diminishes this exaggerated response in most of the software tested. We have further affirmed that DNAstar-Deseq2 gives a more conservative transcriptome expression pattern which appears more suitable for studies expecting subtle gene expression patterns. [ABSTRACT FROM AUTHOR]

Pike killifish Belonesox belizanus is an established non‐native fish species in Florida, USA, that was first documented in south Florida in 1957 and then in Tampa Bay tributaries in 1994. Decreases in small‐bodied fish abundances have been linked to the introduction of B. belizanus in both of these regions. Increases in the range and abundance of B. belizanus in the Tampa Bay area and overlap in habitat usage have led to concerns about potential competition with, and predation on, early‐juvenile common snook Centropomus undecimalis [≤100 mm standard length (SL)]. Stomach contents of B. belizanus (N = 422; 14–127 mm SL) and early‐juvenile C. undecimalis (N = 1132; 5–119 mm SL) were collected to examine the dietary overlap of these two species and potential differences in the diet of early‐juvenile C. undecimalis from locations with and without B. belizanus co‐occurring. Prey resources were collected by seine to assess prey resource limitation and prey selectivity. Stomach content analysis indicated that there was low overlap in the diet of early‐juvenile C. undecimalis and B. belizanus (C ≤ 0.40). Early‐juvenile C. undecimalis had a wider diet breadth, consuming many organisms that are not consumed by B. belizanus and which make up a large portion of the early‐juvenile C. undecimalis diet. Analysis of prey resources indicated that some prey groups may have lower abundances in locations where B. belizanus are present, with some of these differences reflected in the diet of early‐juvenile C. undecimalis. Despite these differences, there was minimal difference in the diet overlap of early‐juvenile C. undecimalis from locations with and without B. belizanus co‐occurring. Currently B. belizanus appear to be competing minimally with early‐juvenile C. undecimalis for prey resources, with no substantial impacts being detected. [ABSTRACT FROM AUTHOR]

Managing and understanding fisheries dynamics are becoming more complex as new and seemingly more complicated environmental factors are identified. Often management requires resources beyond that of any one entity and calls for collaboration among partners with differing priorities and backgrounds to account for the complexity of factors influencing fisheries. We present a collaborative case study from the Susquehanna River basin, Pennsylvania, where Smallmouth Bass Micropterus dolomieu have faced population declines, mortality events, and notable signs of disease in recent years. Collaboration was required to study many facets of the fishery and the environment simultaneously to better understand risk factors and underlying relationships influencing Smallmouth Bass health. The outcomes from this interdisciplinary collaboration allowed for identification of contributing risk factors, led to the development of products and analytical techniques that were mutually beneficial to all partners involved, and provided knowledge that was integrated into fish health and fisheries management. [ABSTRACT FROM AUTHOR]

Temporally separated species are often thought to have limited competition over a shared resource. However, early arriving species may consume a limited resource such that later‐arriving species have access to fewer resources and thus experience competitive effects, even if they are temporally separated (i.e., they experience legacy effects from the early species). The presence of a predator might affect potential legacy effects by influencing the behavior or survivorship of the early species. Using a mesocosm experiment, I examined whether the presence of nonnative Western Mosquitofish (Gambusia affinis) mediated legacy effects in the interaction of two temporally separated species of tadpoles, early arriving American Toads (Anaxyrus americanus) and late‐arriving Bullfrogs (Rana catesbeiana). Anaxyrus americanus tadpoles reduced R. catesbeiana tadpole growth despite all A. americanus tadpoles metamorphosing 8 days before the introduction of R. catesbeiana tadpoles into the mesocosms (i.e., legacy effects). Gambusia affinis had limited effects on A. americanus (1 day delay in metamorphosis but no effect on survivorship or size at metamorphosis) and positive effects on R. catesbeiana (increased growth). There were no significant interactions between the A. americanus tadpole density and G. affinis treatments. In conclusion, I found evidence of significant legacy effects of A. americanus tadpoles on R. catesbeiana tadpoles, but no evidence that G. affinis mediated the legacy effects. [ABSTRACT FROM AUTHOR]

Plethodontid salamanders often possess the ability to detect and avoid hazards in the environment which may be important for survival. We examined whether the two main colour morphs of Plethodon cinereus differ in their avoidance of cues from a potential predator (Thamnophis sirtalis) and whether P. cinereus avoided cues from T. sirtalis of different sizes (i.e., small vs. large). Plethodon cinereus avoided chemical cues deposited by T. sirtalis on a substrate; but avoidance did not differ between colour morphs of P. cinereus , snake sizes, or individual donor snakes. [ABSTRACT FROM AUTHOR]

Given a vector bundle E on a tree of smooth rational curves C, we give necessary and sufficient conditions for a vector bundle E ′ on P 1 to specialize to E on C, generalizing the rank 2 case, due to Coskun. [ABSTRACT FROM AUTHOR]

Let X be a projective variety and let C be a rational normal curve on X. We compute the normal bundle of C in a general complete intersection of hypersurfaces of sufficiently large degree in X. As a result, we establish the separable rational connectedness of a large class of varieties, including general Fano complete intersections of hypersurfaces of degree at least three in flag varieties, in arbitrary characteristic. In addition, we give a new way of computing the normal bundle of certain rational curves in products of varieties in terms of their restricted tangent bundles and normal bundles on each factor. [ABSTRACT FROM AUTHOR]

Background: The purpose of this study was to define the features of scapular morphology that are associated with changes in the critical shoulder angle (CSA) by developing the best predictive model for the CSA based on multiple potential explanatory variables, using a completely 3D assessment. Methods: 3D meshes were created from CT DICOMs using InVesalius (Vers 3.1.1, RTI [Renato Archer Information Technology Centre], Brazil) and Meshmixer (3.4.35, Autodesk Inc., San Rafael, CA). The analysis included 17 potential angular, weighted linear and area measurements. The correlation of the explanatory variables with the CSA was investigated with the Pearson's correlation coefficient. Using multivariable linear regression, the approach for predictive model-building was leave-one-out cross-validation and best subset selection. Results: Fifty-three meshes were analysed. Glenoid inclination (GI) and coronal plane angulation of the acromion (CPAA) [Pearson's r: 0.535; -0.502] correlated best with CSA. The best model (adjusted R-squared value 0.67) for CSA prediction contained 10 explanatory variables including glenoid, scapular spine and acromial factors. CPAA and GI were the most important based on their distribution, estimate of coefficients and loss in predictive power if removed. Conclusions: The relationship between scapular morphology and CSA is more complex than the concept of it being dictated solely by GI and acromial horizontal offset and includes glenoid, scapular spine and acromial factors of which CPAA and GI are most important. A further investigation in a closely defined cohort with rotator cuff tears is required before drawing any clinical conclusions about the role of surgical modification of scapular morphology. Level of evidence: Level 4 retrospective observational cohort study with no comparison group. [ABSTRACT FROM AUTHOR]

Background: The purpose of this study was to define the features of scapular morphology that are associated with changes in the critical shoulder angle (CSA) by developing the best predictive model for the CSA based on multiple potential explanatory variables, using a completely 3D assessment.Methods: 3D meshes were created from CT DICOMs using InVesalius (Vers 3.1.1, RTI [Renato Archer Information Technology Centre], Brazil) and Meshmixer (3.4.35, Autodesk Inc., San Rafael, CA). The analysis included 17 potential angular, weighted linear and area measurements. The correlation of the explanatory variables with the CSA was investigated with the Pearson's correlation coefficient. Using multivariable linear regression, the approach for predictive model-building was leave-one-out cross-validation and best subset selection.Results: Fifty-three meshes were analysed. Glenoid inclination (GI) and coronal plane angulation of the acromion (CPAA) [Pearson's r: 0.535; -0.502] correlated best with CSA. The best model (adjusted R-squared value 0.67) for CSA prediction contained 10 explanatory variables including glenoid, scapular spine and acromial factors. CPAA and GI were the most important based on their distribution, estimate of coefficients and loss in predictive power if removed.Conclusions: The relationship between scapular morphology and CSA is more complex than the concept of it being dictated solely by GI and acromial horizontal offset and includes glenoid, scapular spine and acromial factors of which CPAA and GI are most important. A further investigation in a closely defined cohort with rotator cuff tears is required before drawing any clinical conclusions about the role of surgical modification of scapular morphology.Level Of Evidence: Level 4 retrospective observational cohort study with no comparison group. [ABSTRACT FROM AUTHOR]

Rosaleen Duffy became a prominent student and critic of international wildlife conservation when she published I Killing for Conservation i (Duffy [2]), a wonderfully detailed study of wildlife policy in Zimbabwe. Security and Conservation: The Politics of the Illegal Wildlife Trade by Duffy, Rosaleen. For example, active and retired military people helped enforce fortress conservation, the focus has shifted to community-based resource management, and conservation has begun to reflect neoliberal impulses to make wildlife conservation pay its way. [Extracted from the article]

Introduction: FLT3 internal tandem duplicate (ITD) is associated with unfavorable prognosis of acute myeloid leukemia; targeted therapy improves clinical outcome. We propose that FLT3‐ITD detected by next generation sequencing (NGS) should be reported with the same nomenclature pattern as single nucleotide variants so that the mutation can be better interpreted clinically. Methods: A Python‐based web application was developed to generate FLT3‐ITD nomenclature as recommended by the Human Genome Variation Society (HGVS). Assembled FLT3‐ITD sequences from 84 patients and 11 artificially created ITD sequences were used for the validation of this web‐based application. Each sequence was inspected manually to confirm that the nomenclature was accurate. Results: Accurate nomenclatures were generated for 113 of 114 sequencing results and 7 artificial sequences. One assembled sequence and four artificial sequences were not named accurately; warning statements were automatically generated to alert further inspection. Of the 105 unique FLT3‐ITDs, the ITD lengths range from 18 to 300 bp. Depending whether the ITD involves intron or extends into exon 15, three patterns were recognized. Only 44 (42%) ITDs were pure duplications, and three types of variants were identified at the 5′ of ITD. When ITD involves intronic sequence, the protein may comprise inserted amino acids encoded by the intron, due to disrupted RNA splicing. Conclusion: The web application generates accurate FLT3‐ITD nomenclature from NGS results except in rare situations. The HGVS nomenclatures provide information on the molecular architecture of FLT3‐ITDs and reveal details of complex insertions with partial duplications. [ABSTRACT FROM AUTHOR]

Robert Heizer excavated Leonard Rockshelter (26Pe14) in western Nevada more than 70 years ago. He described stratified cultural deposits spanning the Holocene. He also reported obsidian flakes purportedly associated with late Pleistocene sediments, suggesting that human use extended even farther back in time. Because Heizer never produced a final report, Leonard Rockshelter faded into obscurity despite the possibility that it might contain a Clovis Era or older occupation. That possibility prompted our team of researchers from the University of Nevada, Reno and Desert Research Institute to return to the site in 2018 and 2019. We relocated the excavation block from which Heizer both recovered the flakes and obtained a late Pleistocene date on nearby sediments. We minimally excavated undisturbed deposits to rerecord and redate the strata. As an independent means of evaluating Heizer's findings, we also directly dated 12 organic artifacts housed at the Phoebe A. Hearst Museum of Anthropology. Our work demonstrates that people did not visit Leonard Rockshelter during the late Pleistocene. Rather, they first visited the site immediately following the Younger Dryas (12,900-11,700 cal BP) and sporadically used the shelter, mostly to store gear, throughout the Holocene. [ABSTRACT FROM AUTHOR]

Let ϕ:X→Pn$\phi :X\rightarrow \mathbb {P}^n$ be a morphism of varieties. Given a hyperplane H$H$ in Pn$\mathbb {P}^n$, there is a Gysin map from the compactly supported cohomology of ϕ−1(H)$\phi ^{-1}(H)$ to that of X$X$. We give conditions on the degree of the cohomology under which this map is an isomorphism for all but a low‐dimensional set of hyperplanes, generalizing results due to Skorobogatov, Benoist, and Poonen‐Slavov. Our argument is based on Beilinson's theory of singular supports for étale sheaves. [ABSTRACT FROM AUTHOR]

Studies of elevational variation in diets in lizards have often found shifts in diet composition among elevations. Herein, we studied the diets of Sceloporus variabilis from six populations found in a variety of habitats along an elevational gradient (3–1900 m) in Puebla and Veracruz, Mexico. Diets of S. variabilis for the six populations were similar at the order level, with hymenopterans and coleopterans being the most important prey items. However, the specific taxa at the family or genus level varied among the six populations. The presence of plant material in diets varied among the six populations, with the two lowest elevation populations and the highest elevation population containing the most of this material. [ABSTRACT FROM AUTHOR]

Mite prevalence and load can vary among populations and species of lizards. We report on chigger mite (Eutrombicula alfreddugesi) prevalence and load in a temperate population of Xenosaurus fractus and a subtropical population of Xenosaurus rectocollaris. Mites were more prevalent and found in greater numbers (i.e., higher load) on X. recto - collaris than on X. fractus. Mite load in both species did not differ between July/August and October/November. Differences in mite load and prevalence among populations and species of Xenosaurus from different types of environment suggest that more study is needed to understand how environmental factors affect mite infestation in crevice-dwelling Xenosaurus. [ABSTRACT FROM AUTHOR]

Background: In this comparative study we evaluate the performance of four software tools: DNAstar-D (DESeq2), DNAstar-E (edgeR), CLC Genomics and Partek Flow for identification of differentially expressed genes (DEGs) using a transcriptome of E. coli. The RNA-seq data are from the effect of below-background radiation 5.5 nGy total dose (0.2nGy/hr) on E. coli grown shielded from natural radiation 655 m below ground in a pre-World War II steel vault. The gene expression response to three supplemented sources of radiation designed to mimic natural background, 1952 – 5720 nGy in total dose (71–208 nGy/hr), are compared to this "radiation-deprived" treatment. In addition, RNA-seq data of Caenorhabditis elegans nematode from similar radiation treatments was analyzed by three of the software packages. Results: In E. coli, the four software programs identified one of the supplementary sources of radiation (KCl) to evoke about 5 times more transcribed genes than the minus-radiation treatment (69–114 differentially expressed genes, DEGs), and so the rest of the analyses used this KCl vs "Minus" comparison. After imposing a 30-read minimum cutoff, one of the DNAStar options shared two of the three steps (mapping, normalization, and statistic) with Partek Flow (they both used median of ratios to normalize and the DESeq2 statistical package), and these two programs identified the highest number of DEGs in common with each other (53). In contrast, when the programs used different approaches in each of the three steps, between 31 and 40 DEGs were found in common. Regarding the extent of expression differences, three of the four programs gave high fold-change results (15–178 fold), but one (DNAstar's DESeq2) resulted in more conservative fold-changes (1.5–3.5). In a parallel study comparing three qPCR commercial validation software programs, these programs also gave variable results as to which genes were significantly regulated. Similarly, the C. elegans analysis showed exaggerated fold-changes in CLC and DNAstar's edgeR while DNAstar-D was more conservative. Conclusions: Regarding the extent of expression (fold-change), and considering the subtlety of the very low level radiation treatments, in E. coli three of the four programs gave what we consider exaggerated fold-change results (15 – 178 fold), but one (DNAstar's DESeq2) gave more realistic fold-changes (1.5–3.5). When RT-qPCR validation comparisons to transcriptome results were carried out, they supported the more conservative DNAstar-D's expression results. When another model organism's (nematode) response to these radiation differences was similarly analyzed, DNAstar-D also resulted in the most conservative expression patterns. Therefore, we would propose DESeq2 ("DNAstar-D") as an appropriate software tool for differential gene expression studies for treatments expected to give subtle transcriptome responses. [ABSTRACT FROM AUTHOR]

Mexico is a megadiverse country with high endemicity in its herpetofauna. We examine how species richness, proportion of state and country endemic species, and proportion of species in a category of conservation concern using listings in the International Union for Conservation of Nature (IUCN) Red List and the Secretaría del Medio Ambiente y Recursos Naturales (SEMARNAT) in 27 of 32 Mexican states are related to environmental and human demographic and socioeconomic variables. Amphibian and reptile species richness were positively related to latitude range and number of physiographic regions and negatively related to latitude. The proportion of state endemic amphibian species in a state was negatively related to latitude whereas no variables influenced the proportion in reptiles. The proportion of country endemics in a state was positively related to human population density and the number of physiographic regions and negatively related to per capita gross domestic product (GDP) and latitude range for amphibians; it was positively related to human population density and elevation range and negatively related to latitude range for reptiles. The proportion of amphibian species in an IUCN category of concern in a state was positively related to human population density and negatively related to latitude; for reptiles, it was negatively related to human population density. The proportion of SEMARNAT-listed species in a state was positively related to human population density for both amphibians and reptiles and negatively related to latitude range for amphibians. Our analyses found that larger macroecological patterns (e.g., latitudinal species gradient, heterogeneity-richness relationships) and human population density play important roles in determining the richness and conservation status of Mexican amphibians and reptiles. [ABSTRACT FROM AUTHOR]

The endangered, endemic salamander, Ambystoma altamirani, is distributed in streams in the Transvolcanic Belt around Mexico City. Like other Mexican ambystomatids, A. altamirani is threatened by several anthropogenic stressors, including land use changes. Here we examine how aspects of the terrestrial habitat, such as the distance to wooded habitats and the presence of livestock, as well as several aspects of the aquatic habitat, affect the abundance of adult and larval A. altamirani along the Arroyo los Axolotes. The presence of livestock and proximity to the nearest trees did not affect the abundance of adult or larval A. altamirani. The abundance of adult A. altamirani was positively associated to the proportion of visits with water, mean total dissolved solids, mean stream width, mean bank height, and mean water velocity, and negatively related to mean water temperature and mean water depth. The abundance of larvae was not related to any measured variables. In conclusion, the abundance of A. altamirani along the Arroyo los Axolotes is primarily associated with aquatic factors, with limited influence of terrestrial factors. From a conservation and management perspective it is imperative to conserve the aquatic characteristics of streams where A. altamirani is found. [ABSTRACT FROM AUTHOR]

Purpose: The objective of this study was to compare the biomechanics of using a double layered human dermal allograft to a single layered human dermal allograft in superior capsular reconstruction. Methods: Five cadaveric shoulders were tested. The superior translation of the humerus and the subacromial contact pressure were measured at 0°, 30° and 60° of glenohumeral abduction in the following six conditions: (1) intact rotator cuff, (2) irreparable supraspinatus tear, (3) superior capsular reconstruction using a double layered human dermal allograft with and (4) without posterior suturing, (5) superior capsular reconstruction using a single human dermal allograft with and (6) without posterior suturing. Results: There was a significant increase in superior translation of the humerus and subacromial contact pressure when comparing torn supraspinatus to intact shoulder. All superior capsular reconstruction repairs lead to a reduction in superior translation and subacromial contact pressures compared to after the supraspinatus tear except for single layered superior capsular reconstruction repair without posterior suturing. There was no difference in superior translation and subacromial contact pressures comparing the intact shoulder to any of the superior capsular reconstruction constructs. Conclusion: Superior capsular reconstruction using a single or double layered human dermal allograft improves superior translation after supraspinatus repair. There is some biomechanical benefit of a double layered human dermal allograft technique over a single layered graft technique in superior capsular reconstruction. Level of Evidence: IV [ABSTRACT FROM AUTHOR]

Water loss and gain rates of amphibians are important to understanding their ecology, especially for plethodontid salamanders. We report the first estimates of repeatability of relative water loss and gain rates of the two major colour morphs of the Eastern Red-backed Salamander, Plethodon cinereus , in the fall and spring seasons. Repeatability of relative water loss in P. cinereus was >0 in the fall but not in the spring. Repeatability of relative water gain was significant for all salamanders pooled in the fall, and was not repeatable in the spring. There were no apparent differences in repeatability of relative water loss or gain between the two colour morphs. Our results suggest that the repeatability of relative water loss and gain rates varies by season, but not by colour morph. [ABSTRACT FROM AUTHOR]

In this paper, we investigate an arithmetic analogue of the gonality of a smooth projective curve |$C$| over a number field |$k$|⁠ : the minimal |$e$| such that there are infinitely many points |$P \in C(\bar{k})$| with |$[k(P):k] \leqslant e$|⁠. Developing techniques that make use of an auxiliary smooth surface containing the curve, we show that this invariant can take any value subject to constraints imposed by the gonality. Building on work of Debarre–Klassen, we show that this invariant is equal to the gonality for all sufficiently ample curves on a surface |$S$| with trivial irregularity. [ABSTRACT FROM AUTHOR]

Objectives: The challenges of implementing clinical practice changes are well recognised. Prevailing approaches to tackling them have largely relied on increasing control and standardisation, but with limited impact. We examine research from the behavioural sciences in an attempt to (a) build a clearer understanding of why the implementation of change in clinical settings has proved so elusive and (b) provide practical guidance on how organisations can create a climate that can nurture sustained behavioural change in their workforce. Method: We undertook a review of the behavioural science literature to gain a better understanding of the circumstances under which staff might willingly pursue goals that are externally generated. Three studies, derived from the mental health literature, are outlined to illustrate how the manner in which change is introduced can have a significant effect on its uptake and sustainability. Results: Research suggests that human behaviour is not as unpredictable as it might at first appear; rather, there are some deeply rooted, psychological processes at play. Self-Determination Theory, a theory of human motivation with an extensive body of research supporting its effectiveness, suggests that the manner in which change is introduced and implemented is critical. Conclusion: While improvement methodologies and the use of implementation strategies are necessary, experience would suggest that by themselves they are not sufficient. Overcoming the challenges of implementing change will require a significant shift in our thinking about organisational leadership and the way that change is introduced. Some practical ways leaders can foster staff buy-in for organisational change are proposed. [ABSTRACT FROM AUTHOR]

In lizards, flight initiation distance (FID), the distance between a prey individual and a predator when escape begins, can be affected by numerous intrinsic and extrinsic factors, including sex, temperature, and level of conspicuousness. Here we report on a study of FID in a population of Ornate Tree Lizards, Urosaurus ornatus, from the Sierra de Samalyuca, Chihuahua, Mexico which are cryptic due to their dorsal coloration blending into their background. Urosaurus ornatus in our study population allowed close approaches (mean FID = 65 cm). Mean FID did not differ between males and females. We also found no effect of body, air, or substrate temperature on FID. The short FID we observed may be related to the cryptic nature of U. ornatus. [ABSTRACT FROM AUTHOR]

Amphibians often select oviposition sites based on a variety of cues that indicate the level of risk in the oviposition habitat. Surprisingly, the role of aquatic vegetation or habitat structure/complexity in anuran oviposition site selection has not been extensively studied even though it might affect perceived risk. We examined the effects of free-ranging invasive western mosquitofish (Gambusia affinis) and artificial vegetation/habitat structure on colonisation of experimental pools by gray treefrogs (Hyla versicolor). Hyla versicolor avoided ovipositing in mesocosms with G. affinis. The presence of artificial vegetation/habitat structure had no effect on oviposition site selection by H. versicolor, whether alone or in interaction with G. affinis. Our experiment provides evidence for the avoidance of fish, and more specifically G. affinis, by ovipositing H. versicolor; but provides no evidence for a role of vegetation/habitat structure. [ABSTRACT FROM AUTHOR]

Invasive predators might serve as ecological filters for prey communities, either through non-consumptive or consumptive effects. The Western Mosquitofish (Gambusia affinis [Baird and Girard, 1853]) is an invasive non-native fish that affects native aquatic communities, potentially because of effects on oviposition or initial colonization of habitats (non-consumptive effects), post-colonization effects (i.e., consumptive effects), or a combination of both non-consumptive and consumptive effects. We conducted a mesocosm experiment to examine non-consumptive and consumptive effects of G. affinis on colonization of experimental ponds by native macroinvertebrates. We predicted that, if G. affinis affects macroinvertebrates through non-consumptive effects, there would be lower abundances in both the non-lethal (caged G. affinis) and lethal (free-ranging G. affinis) treatments compared to the control (no G. affinis), whereas, if the effect of G. affinis is primarily due to consumptive effects, there would be lower abundances of macroinvertebrates in the lethal treatment compared to the non-lethal and control treatments. Most macroinvertebrate taxa (dytiscid beetles, baetid Ephemeroptera, corixid and gerrid hemipterans, libellulid odonates) were less abundant, or even absent, in the presence of G. affinis in the lethal treatment compared to their abundance in the non-lethal G. affinis treatment; however, notonectids were not affected by treatment. The invasive fish predator, G. affinis , therefore, can act as an ecological filter for macroinvertebrates in invaded aquatic habitats, primarily through lethal consumptive effects. [ABSTRACT FROM AUTHOR]

A single radiocarbon date derived from the Buhl burial in south-central Idaho has frequently been used as a data point for the interpretation of theWestern Stemmed Tradition (WST) chronology and technology because of the stemmed biface found in situ with the human remains. AMS dating of bone collagen in 1991 produced an age of 10,675 ± 95 14C BP, immediately postdating the most widely accepted age range for Clovis. The Buhl burial has been cited as evidence that stemmed point technology may have overlapped with Clovis technology in the Intermountain West. We discuss concerns about the radiocarbon date, arguing that even at face value, the calibrated date has minimal overlap with Clovis at the 95.4% range. Furthermore, the C:N ratio of 3.69 in the analyzed collagen is outside of the typical range for well-preserved samples, indicating a postdepositional change in carbon composition, which may make the date erroneously older or younger than the age of the skeleton. Finally, the potential dietary incorporation of small amounts of anadromous fish may indicate that the burial is younger than traditionally accepted. For these reasons, we argue that the Buhl burial cannot be used as evidence of overlap between WST and Clovis. [ABSTRACT FROM AUTHOR]

We used a 36-yr study of a turtle community in a northern Indiana lake to examine shell anomalies and temporal changes in their frequency in 3 species. The overall frequency of shell anomalies was 17% in painted turtles (Chrysemys picta), 11% in northern map turtles (Graptemys geographica), and 18% in red-eared sliders (Trachemys scripta elegans), and there were more anomalies on the carapace than on the plastron in 2 species (C. picta and G. geographica). The probability that an individual would have a shell anomaly was affected negatively by year of first capture and estimated year of hatching in C. picta and by carapace length at first capture in C. picta and T. s. elegans, although the relationships were weak (all r2 ≤ 0.15). Thus, there was no suggestion of a systematic change in shell anomalies over time in the Dewart Lake turtle community. [ABSTRACT FROM AUTHOR]

The Smallmouth Bass Micropterus dolomieu fishery in the Susquehanna River basin, Pennsylvania, is one of the most socioeconomically important fisheries in the region and has recently undergone considerable changes. These changes started in 2005, when disease was documented in young‐of‐the‐year (age‐0) Smallmouth Bass. Shortly thereafter, declines in abundance of both juveniles and adults were observed. These declines in abundance coincided with disease infections in age‐0, intersex in adults, and concerns regarding contaminant exposure. Natural mortality rates, particularly for age‐0, increased during this period (2005–2011), and there were concerns for the overall health of this world‐class fishery. However, in recent years (2012–2017), there have been decreases in both mortality rates and external observations of disease and increases in abundance across multiple size‐classes. Recent changes are encouraging for the future of the Smallmouth Bass fishery in the Susquehanna River. Yet, in light of the ever changing environmental, social, and anthropogenic influences on aquatic ecosystems, there remain concerns for Smallmouth Bass health and management. Because of this, ongoing research efforts are needed to monitor population and health changes and to conduct integrative research that considers complex relationships between organisms and their environments. [ABSTRACT FROM AUTHOR]

The State of Mexico has a unique combination of geographic characteristics and topography that promotes a high biodiversity. Unfortunately, continued human population growth of the metropolitan areas of Mexico City and Toluca have degraded the environment of the State of Mexico, which threatened its wildlife. An updated checklist of the amphibians and reptiles of the State of Mexico is provided and their conservation status summarized. The State of Mexico has 49 species of amphibians and 101 species of reptiles. The majority of the amphibians (73.5%) and reptiles (70.3%) found in the State of Mexico are endemic to Mexico. Of the amphibian and reptile species in the State of Mexico, 20.1% are IUCN listed (i.e., Vulnerable, Near Threatened, or Endangered), 18.4% are placed in a protected category by SEMARNAT (excluding NL and Pr, this last category is equivalent to the LC category of IUCN), and 34.9% are categorized as high risk by the EVS. The importance of forested habitats for the protected amphibians and reptiles in the State of Mexico suggest that management of these habitats to maintain or expand them needs to be considered. [ABSTRACT FROM AUTHOR]

Mexico City houses one of the most populous urban areas of the world, and the modification of its natural habitat likely influences the biological diversity found there. In particular, amphibians and reptiles are likely affected by these modifications. Herein, we present an updated list of the species of amphibians and reptiles that inhabit Mexico City. Mexico City harbors 65 species of amphibians and reptiles, which represent 21 families and 33 genera. These include 18 species of amphibians (nine anurans and nine salamanders) and 47 species of reptiles (14 lizards, 30 snakes [one introduced], and three turtles [one introduced]). Forty-eight of the amphibian and reptile species in Mexico City are endemic to Mexico, with two endemic to Mexico City. The most diverse region of Mexico City is the Forests and Ravines region, which is home to 43 species. Eleven species of amphibians and reptiles in Mexico City are IUCN listed, 16 are placed in a protected category by SEMARNAT (Secretaria del Medio Ambiente y Recursos Naturales), and 27 species are categorized as high risk by the EVS (Environmental Viability Score). Mexico City shares almost 94% of its species with the State of Mexico. [ABSTRACT FROM AUTHOR]

Ambystoma altamirani is an endangered salamander found in high mountain streams in the vicinity of México City, and its populations might be threatened by urban growth. Here we report our research on a previously unstudied population of A. altamirani at the Llano de Lobos in the Sierra de las Cruces. The study ran from September 2018 to September 2019. The number of observed individuals was relatively constant across months. The only months when we observed gilled adults were February and July, and the only months when we saw juveniles without gills were January, February, and August, suggesting that the transformation of juveniles to adults takes place twice a year, once in January -February and once in July-August. We observed egg masses in December and January, and larvae from March to May and also in July. The sex ratio was significantly female-biased (about 2:1). We observed A. altamirani at 3 of the 25 permanent sites during the study period. Our comparison of the characteristics of occupied sites with those of unoccupied sites suggests that availability of sunlight (i.e., less cover) and low levels of human impact are important for occupancy by A. altamirani. These findings are consistent with observations of other populations of A. altamirani, suggesting that these characteristics might be important in their management and conservation. [ABSTRACT FROM AUTHOR]

Despite being one of the smallest states in Mexico, the high diversity of habitats in Morelos has led to the development of a rich biota made up of a mixture of species typical of the Neovolcanic Axis and the Sierra Madre del Sur. However, recent expansion of cities in Morelos is likely to have consequences for the state's herpetofauna. Here a checklist of the amphibians and reptiles of Morelos is provided with a summary of their conservation status and overlap with its neighboring states. Morelos is home to 139 species of amphibians and reptiles representing 32 families and 75 genera. Twenty-six of the 38 species of amphibians and 70 of the 101 species of reptiles that inhabit Morelos are endemic to Mexico. Fourteen species of amphibians and reptiles from Morelos are IUCN listed (i.e., Vulnerable, Near Threatened, or Endangered), 22 are placed in a protected category by SEMARNAT, and 41 are categorized as high risk by the EVS. The Tropical Deciduous Forest vegetation type hosts the greatest number of amphibian and reptile species in Morelos (84 species). Morelos shares the largest proportion of its herpetofauna with the State of Mexico (79.3%), Puebla (77.0%), and Guerrero (74.8%). [ABSTRACT FROM AUTHOR]

Sinaloa possesses a rich biota with unique characteristics due to its proximity to the northern deserts, the tropical lowlands of the south, and the temperate environments of the western slopes of the Sierra Madre Occidental in Mexico. However, threats to its environment makes understanding the biological diversity of Sinaloa crucial. A checklist of the amphibians and reptiles has been generated, and the conservation status of Sinaloa's herpetofauna summarized with the aim of understanding the potential conservation or management needs. Sinaloa has 159 species of amphibians and reptiles, including 39 species of amphibians and 120 species of reptiles. The herpetofauna of Sinaloa has relatively few species of conservation concern at a global and national scale (IUCN and SEMARNAT lists), but Environmental Vulnerability Scores suggest that there might be greater conservation concerns for the Sinaloa herpetofauna. Families of particular conservation concern include Craugastoridae, Eleutherodactylidae, Ambystomatidae, Crocodylidae, Dactyloidae, Eublepharidae, Helodermatidae, Iguanidae, Phrynosomatidae, Phyllodactylidae, Colubridae, Natricidae, Viperidae, Cheloniidae, and Dermochelyidae. [ABSTRACT FROM AUTHOR]

Colima is the fourth smallest Mexican state, covering only 0.3% of the surface area of Mexico, but due to the remarkable diversity of physiographic and environmental conditions present in Colima it contains a high biological diversity. We generated an up-to-date herpetofaunal checklist for Colima, with a summary of the conservation status of Colima's amphibians and reptiles. Our checklist contains a total of 153 species of amphibians and reptiles (three introduced). Thirty-nine are amphibians and 114 are reptiles. More than half of Colima's herpetofauna are Mexican endemics (66.7% of amphibians, 67.5% of reptiles). Less than 25% of the amphibian and reptile species in Colima are in protected categories according to the IUCN Red List and SEMARNAT. The reptiles in the Marine and Revillagigedo Archipelago regions are the most threatened taxa of the Colima herpetofauna. Colima shares > 80% of its herpetofauna with its neighboring states, Jalisco and Michoacán. [ABSTRACT FROM AUTHOR]

Lizards in the genus Xenosaurus are crevice-dwelling lizards. Their crevice-dwelling habit may constrain their ecology; thus one might predict there could be limited variation in several ecological traits among species. Here we report on aspects of the ecology of the recently described Xenosaurus fractus from the Sierra Nororiental of Puebla, Mexico and compare it to other species of Xenosaurus. Mean body temperature of X. fractus was 19.67°C. Body temperature was related to air temperature and substrate temperature. We found no difference in thermal ecology between males and females. Crevice use was not related to the individual's body size, nor did male and females differ in crevice use. Crevice characteristics had limited effects on body temperature. Sexual size dimorphism was not present in body size or head size, except for dimorphism in the relative growth of head width with snout-vent length. Xenosaurus fractus ate mostly insects, with caterpillars the most important prey. In conclusion, the ecology of X. fractus is similar to other species of Xenosaurus in many ways. Of particular interest is the observation that X. fractus does not appear to be any more similar to its sister species X. tzacualtepantecus than it is to other species of Xenosaurus. [ABSTRACT FROM AUTHOR]

Body size, growth, and longevity in Northern Map Turtles (Graptemys geographica) from Dewart Lake in northern Indiana were studied from 1979 to 2016. Based on captures of 214 males {72 recaptures) and 99 females {40 recaptures), we generated von Bertalanffy growth equations which corroborated our growth curves based on counts of plastral growth rings and recaptured turtles. Females diverge from males in their faster growth by the end of their second season. Our oldest females were only 18-20 seasons old, and the oldest males were only 13-15 seasons old, suggesting a short generation time and a possible sexual difference in longevity. For the species, we detected no latitudinal pattern of size or age at maturity but found some support for a latitudinal increase in body size in accordance with Bergmann's Rule. [ABSTRACT FROM AUTHOR]

While there has been a significant increase in investment in community mental health in Australia since the advent of the National Mental Health Strategy in the early 1990s, there has been little guidance on service design and delivery. This has led to a growing diversity of approaches and concern about the adequacy of care with repeated calls for a system overhaul. Consumers and carers have very largely been absent from decision‐making about service design and development which has led to a system primarily designed by healthcare professionals. However, with the emergence of recovery as a core principle in mental health, it is time for consumers and carers to be centrally engaged in co‐designing services with service providers. This raises the question of whether dominant service delivery models – such as the growth of specialist teams/services, the changing balance between profession‐specific and generic case management roles in multidisciplinary teams, and the separation of inpatient from community care – will prevail. Contentious issues in these three service delivery areas are outlined to stimulate debate and highlight the pressing need for national guidance on the configuration of community mental health services. Building on the lessons learned from the first National Mental Health Strategy, we outline a proposal for a co‐designed National Framework for Community Mental Health Services to guide the delivery of care in a way which satisfies the aspirations of consumers, carers, and mental health professionals alike. [ABSTRACT FROM AUTHOR]

Predation by native and non-native predators on the eggs, embryos, and early stage tadpoles can affect the recruitment of offspring into a population. We examined the effects of native (Little Brown Mudbugs, Cambarus thomai ; overwintered Rana tadpoles; Common Green Darner, Anax junius , larvae) and non-native (Western Mosquitofish, Gambusia affinis) potential predators on the eggs, hatchlings, and early tadpoles of the Green Frog (Lithobates clamitans). The predators had no effect on survivorship or hatching of L. clamitans eggs. However, tadpole survivorship was significantly reduced by dragonfly larvae and crayfish, but not G. affinis or the overwintered ranid tadpoles. Our observation that invertebrates consumed Green Frog tadpoles while vertebrates did not is consistent with palatability contributing to the tadpoles' susceptibility to different predators. Our results therefore suggest Green Frog tadpoles, but not eggs or embryos, from some populations may be subject to differential predation by invertebrate and vertebrate predators. [ABSTRACT FROM AUTHOR]

CougarMountain Cave is located in Oregon's Fort Rock Basin. In 1958, avocationalist John Cowles excavated most of the cave's deposits and recovered abundant fiber, lithic, wood, and osseous artifacts. A crewfromtheUniversity of California, Davis returned to the site in 1966 to evaluate the potential for further research, collecting additional lithic and fiber artifacts from disturbed deposits and in situ charcoal from apparently undisturbed deposits. Because Cowles took few notes or photographs, the Cougar Mountain Cave collection--most of which is housed at the Favell Museum in Klamath Falls, Oregon--has largely gone unstudied even though it contains diagnostic artifacts spanning the Holocene and, potentially, the terminal Pleistocene. We recently submitted charcoal and basketry from the site for radiocarbon dating, providing the first reliable sense of when Cougar Mountain Cave was first occupied. Our results indicate at least a Younger Dryas age for initial occupation. The directly dated basketry has provided new information about the age ranges and spatial distributions of diagnostic textile types in the northwestern Great Basin. [ABSTRACT FROM AUTHOR]

From naturally occurring disease threats to the deliberate creation of biological weapons, the field of biosecurity encompasses a broad swath of life science research and the associated risks. [ABSTRACT FROM AUTHOR]

Life‐history strategies are known to shift with latitude in many species. While life‐history variation related to body size, reproductive investment, and behavior has been studied for years, another crucial life‐history component is the immune system, which can influence an animal's survival.We measured selected life‐history traits in side‐blotched lizards in southern Utah and Oregon in the field for two consecutive years and conducted a common‐garden experiment in the laboratory to determine how organisms from different latitudes optimize either immunity or reproduction. We observed lizards from southern populations, which are known to be shorter‐lived, had lower immune function during reproduction when compared to northern lizards in 2012, but the relationship reversed in the following year.Our laboratory study revealed that southern lizards healed cutaneous wounds faster and had higher microbiocidal ability when compared to their northern counterparts, but lost mass doing so. The northern lizards ate more than the southern ones and maintained their body mass. It is possible that northern lizards are better adapted to taking advantage of available food resources. Alternatively, southern lizards may have exhibited sickness behavior in response to an immune challenge or reacted more strongly to the stress of captivity.We found differences in life‐history strategies used by animals from different latitudes, and that these changes can shift within a population depending on the weather conditions of the year. Furthermore, when taken from the field and placed into a common‐garden environment, some of these differences in strategy appear to be intrinsic to the animals (i.e., whether they came from southern or northern populations). [ABSTRACT FROM AUTHOR]

Sonora has a rich natural diversity, including reptiles and amphibians. Sonora's location on the United States-Mexico border creates some unique conservation challenges for its wildlife. We compiled a list of the amphibian and reptile species currently known for Sonora, summarized the conservation status of these species, and compared our list of species with known species lists for adjacent states. The herpetofauna of Sonora comprises 200 species of amphibians and reptiles (38 amphibians and 162 reptiles). Overall, Sonora shares the most species with Chihuahua, Sinaloa, and Arizona. Approximately 11% of the amphibian and reptile species are IUCN listed, but 35.5% are placed in a protected category by SEMARNAT, and 32.6% are categorized as high risk by the Environmental Vulnerability Score. [ABSTRACT FROM AUTHOR]

Purpose: The self-reinforcement mechanism after double row suturebridge rotator cuff repair generates increasing compressive forces at the tendon footprint with increasing tendon load. Passive range of motion is usually allowed after rotator cuff repair. The mechanism of self-reinforcement could be adversely affected by shoulder abduction.Methods: Rotator cuff tears were created ex vivo in nine pairs of ovine shoulders. Two different repair techniques were used. One group was repaired using a double row 'suturebridge' construct with tied horizontal medial row mattress sutures (Knotted repair group). The other group was repaired identically except that medial row knots were not tied (Knotless repair group). Footprint compression was measured at varying amounts of abduction and under tendon loads of 0, 10, 20, 30, 40, 50 and 60N. The rate of increase of contact pressure (degree of self-reinforcement) was calculated for each abduction angle.Results: Abduction diminishes footprint contact pressure in both knotted and knotless double row suturebridge constructs. Progressive abduction from 0 to 40 abduction in the knotless group and 0-30 in the knotted group results in a decrease in self-reinforcement. Abduction beyond this does not cause a further decrease in self-reinforcement. There was no difference in the rate of increase of footprint contact pressure at each angle of abduction when comparing the knotted and knotless groups.Conclusion: In the post-operative period, high tendon load combined with minimal abduction would be expected to generate the greatest amount of footprint compression which may improve tendon healing. Therefore, to maximize footprint compression the use of abduction pillows should be avoided while early isometric strengthening should be used. [ABSTRACT FROM AUTHOR]

Highlights • Greater amberjack sex ratio in the Gulf of Mexico may differ from 1:1. • Sex-specific fishing mortality rates can theoretically alter amberjack sex ratios. • Altered sex ratios influence could influence population dynamics of amberjack. • Incorrect sex ratio assumptions could lead to management issues. • Should incorporate a range of realistic sex ratios into future stock assessments. Abstract The US Gulf of Mexico stock assessment of greater amberjack Seriola dumerili assumes a 1:1 male:female sex ratio. However, the observed sex ratio in the landed catch is 1:1.8, and for fish >1 m fork length is 1:2.4. To theoretically explore whether this female-skewed sex ratio may arise due to differential fishing mortality between the sexes, we used a sex-specific age- and size-based model to investigate how different fishing mortality rates could create a female-skew in the landed catch as well as its subsequent effects on reproductive potential. When fishing mortality rates in the model were equal between the sexes, the sex ratio of the landed catch was approximately 1:1 for all legal-sized fish, and approximately 1:2.4 for fish >1 m FL. However, reproductive potential decreased in comparison to the corresponding scenario with equal fishing mortality rates when fishing mortality rates between the sexes were changed to create the 1:1.8 sex ratio observed in the landed catch. This modeling study demonstrates one possible route that could explain the female-skewed sex ratios observed in the landed catch, and indicates that sex ratio values other than 1:1 should be considered in future stock assessments for Gulf of Mexico greater amberjack. [ABSTRACT FROM AUTHOR]

Formerly in the possession of Harold Willoughby, professor of early Christian origins at the University of Chicago, this unpublished fragment of the Gospel of John in Greek created a stir when it appeared briefly on a well-known auction site in January 2015. Having obtained permission from the owner to edit and publish the manuscript, I offer in this article the results of my analysis of the socalled Willoughby Papyrus, which I have assigned to the third or fourth century. On the basis of new images of the fragment, I provide a transcription of the text, discuss its apparent bookroll format, and assess its text-critical value. Finally, I present the secondary text on the verso and offer some tentative suggestions about its literary character. Though no more than six fragmentary lines survive on either side, the Willoughby Papyrus is of historical interest for three reasons: (1) it is a rare example of a New Testament fragment in which "God" is not abbreviated as a nomen sacrum, a "sacred name"; (2) it furnishes scholars with the first defensible example of a New Testament text written on the front side of an unused bookroll; and (3) it preserves six lines from an otherwise unknown Christian literary text. The Willoughby Papyrus has the potential to provide fresh insight into the emergence and standardization of nomina sacra conventions, the transition from the bookroll to the codex, and the circulation of canonical and noncanonical Christian writings. [ABSTRACT FROM AUTHOR]

Photoacoustic spectroscopy (PAS) has become a popular technique for measuring absorption of light by atmospheric aerosols in both the laboratory and field campaigns. It has low detection limits, measures suspended aerosols, and is insensitive to scattering. But PAS requires rigorous calibration to be applied quantitatively. Often, a PAS instrument is either filled with a gas of known concentration and absorption cross section, such that the absorption in the cell can be calculated from the product of the two, or the absorption is measured independently with a technique such as cavity ring-down spectroscopy. Then, the PAS signal can be regressed upon the known absorption to determine a calibration slope that reflects the sensitivity constant of the cell and microphone. Ozone has been used for calibrating PAS instruments due to its well-known UV–visible absorption spectrum and the ease with which it can be generated. However, it is known to photodissociate up to approximately 1120 nm via the O3 + hν(>1.1eV)→O2(3Σg-) + O(3P) pathway, which is likely to lead to inaccuracies in aerosol measurements. Two recent studies have investigated the use of O3 for PAS calibration but have reached seemingly contradictory conclusions with one finding that it results in a sensitivity that is a factor of 2 low and the other concluding that it is accurate. The present work is meant to add to this discussion by exploring the extent to which O3 photodissociates in the PAS cell and the role that the identity of the bath gas plays in determining the PAS sensitivity. We find a 5 % loss in PAS signal attributable to photodissociation at 532 nm in N2 but no loss in a 5 % mixture of O2 in N2. Furthermore, we discovered a dramatic increase of more than a factor of 2 in the PAS sensitivity as we increased the O2 fraction in the bath gas, which reached an asymptote near 100 % O2 that nearly matched the sensitivity measured with both NO2 and nigrosin particles. We interpret this dependence with a kinetic model that suggests the reason for the observed results is a more efficient transfer of energy from excited O3 to O2 than to N2 by a factor of 22–55 depending on excitation wavelength. Notably, the two prior studies on this topic used different bath gas compositions, and although the results presented here do not fully resolve the differences in their results, they may at least partially explain them. [ABSTRACT FROM AUTHOR]

Photoacoustic spectroscopy (PAS) has become a popular technique for measuring absorption of light by atmospheric aerosols in both the laboratory and in field campaigns. It has low detection limits, measures suspended aerosols, and is insensitive to scattering. But PAS requires rigorous calibration to be applied quantitatively. Often, a PAS instrument is either filled with a gas of known concentration and absorption cross section, such that the absorption in the cell can be calculated from the product of the two, or the absorption is measured independently with a technique such as cavity ringdown spectroscopy. Then, the PAS signal can be regressed upon the known absorption to determine a calibration slope that reflects the sensitivity constant of the cell and microphone. Ozone has been used for calibrating PAS instruments due to its well-known UV-visible absorption spectrum and the ease with which it can be generated. However, it is known to photodissociate up to approximately 1120nm via the O3+hν (>1.1eV)→O2(3+g-)+O(3P) pathway, which is likely to lead to inaccuracies in aerosol measurements. Two recent studies have investigated the use of O3 for PAS calibration but have reached seemingly contradictory conclusions with one finding that it results in a sensitivity that is a factor of two low and the other concluding that it is accurate. The present work is meant to add to this discussion by exploring the extent to which O3 photodissociates in the PAS cell and the role that the identity of the bath gas plays in determining the PAS sensitivity. We find a 5% loss in PAS signal attributable to photodissociation at 532nm in N2 but no loss in a 5% mixture of O2 in N2. Furthermore, we discovered a dramatic increase of more than a factor of two in the PAS sensitivity as we increased the O2 fraction in the bath gas, which reached an asymptote near 100% O2 that nearly matched the sensitivity measured with both NO2 and nigrosin particles. We interpret this dependence with a kinetic model that suggests the reason for the observed results is a more efficient transfer of energy from excited O3 to O2 than to N2 by a factor of 22-55 depending on excitation wavelength. [ABSTRACT FROM AUTHOR]