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The properties of the scattered acoustic vector fields generated by simple spheres illuminated by monotonic continuous wave (CW) plane waves are investigated. Analytical solutions are derived from general acoustic pressure scattering models and analyzed for wave numbers in the resonance region. Of particular interest is the understanding of the characteristics of the scattered acoustic vector field in the near-to-far-field transition region. The separable active and reactive components of the acoustic intensity are used to investigate the structural features of the scattered field components. Numerical results are presented for the near and transition regions for a rigid sphere. A method of mapping nulls in the scattered intensity field components is described. The analysis is then extended to include a simple fluid-filled boundary and finally the evacuated thin-walled shell. Near field acoustic intensity field structures are compared against mechanical material properties of vacuous shells. The ability to extract scattered field features is illustrated with measurements obtained from a recent in-air experiment using an anechoic chamber and acoustic vector sensor probes to measure the scattered acoustic vector field from rigid spheres.

The anatomical basis and adaptive function of the expansion in primate brain size have long been studied; however, we are only beginning to understand the genetic basis of these evolutionary changes. Genes linked to human primary microcephaly have received much attention as they have accelerated evolutionary rates along lineages leading to humans. However, these studies focus narrowly on apes, and the link between microcephaly gene evolution and brain evolution is disputed. We analyzed the molecular evolution of four genes associated with microcephaly (ASPM, CDK5RAP2, CENPJ, MCPH1) across 21 species representing all major clades of anthropoid primates. Contrary to prevailing assumptions, positive selection was not limited to or intensified along the lineage leading to humans. In fact we show that all four loci were subject to positive selection across the anthropoid primate phylogeny. We developed clearly defined hypotheses to explicitly test if selection on these loci was associated with the evolution of brain size. We found positive relationships between both CDK5RAP2 and ASPM and neonatal brain mass and somewhat weaker relationships between these genes and adult brain size. In contrast, there is no evidence linking CENPJ and MCPH1 to brain size evolution. The stronger association of ASPM and CDK5RAP2 evolution with neonatal brain size than with adult brain size is consistent with these loci having a direct effect on prenatal neuronal proliferation. These results suggest that primate brain size may have at least a partially conserved genetic basis. Our results contradict a previous study that linked adaptive evolution of ASPM to changes in relative cortex size; however, our analysis indicates that this conclusion is not robust. Our finding that the coding regions of two widely expressed loci has experienced pervasive positive selection in relation to a complex, quantitative developmental phenotype provides a notable counterexample to the commonly asserted hypothesis that cis-regulatory regions play a dominant role in phenotypic evolution.

The objective of this research is to measure and characterize acoustic energy flow surrounding underwater objects in the near field condition. To accomplish this, we employ prototype acoustic vector sensors which simultaneously measure acoustic pressure and three-dimensional acoustic particle acceleration at a singular point, allowing for precise vector field measurements. In March of 2018, a test at the U.S. Navy’s Dodge Pond Test Facility examined the intensity field surrounding hollow spheres at low ka (wavenumber × radius) values. Phase differences between varying acoustic path lengths from reflected, scattered, and creeping waves result in interference patterns around the object. Various intensity processing techniques are used to reconstruct the acoustic field. Instantaneous intensity describes the time-dependent energy flux of the field and can be divided into active (real) and reactive (imaginary) components, which represent physically real elements. Time-averaged intensity shows energy transport and can be visualized in the form of acoustic streamlines.

The scaling of metabolic rates to body size is widely considered to be of great biological and ecological importance, and much attention has been devoted to determining its theoretical and empirical value. Most debate centers on whether the underlying power law describing metabolic rates is 2/3 (as predicted by scaling of surface area/volume relationships) or 3/4 ("Kleiber's law"). Although recent evidence suggests that empirically derived exponents vary among clades with radically different metabolic strategies, such as ectotherms and endotherms, models, such as the metabolic theory of ecology, depend on the assumption that there is at least a predominant, if not universal, metabolic scaling exponent. Most analyses claimed to support the predictions of general models, however, failed to control for phylogeny. We used phylogenetic generalized least-squares models to estimate allometric slopes for both basal metabolic rate (BMR) and field metabolic rate (FMR) in mammals. Metabolic rate scaling conformed to no single theoretical prediction, but varied significantly among phylogenetic lineages. In some lineages we found a 3/4 exponent, in others a 2/3 exponent, and in yet others exponents differed significantly from both theoretical values. Analysis of the phylogenetic signal in the data indicated that the assumptions of neither species-level analysis nor independent contrasts were met. Analyses that assumed no phylogenetic signal in the data (species-level analysis) or a strong phylogenetic signal (independent contrasts), therefore, returned estimates of allometric slopes that were erroneous in 30% and 50% of cases, respectively. Hence, quantitative estimation of the phylogenetic signal is essential for determining scaling exponents. The lack of evidence for a predominant scaling exponent in these analyses suggests that general models of metabolic scaling, and macro-ecological theories that depend on them, have little explanatory power.

In this study, the properties of the scattered acoustic vector fields generated by simple rigid motionless spheres are investigated. Analytical solutions are derived from general acoustic pressure scattering models, and analyzed for wave numbers in the resonance region. The separable active and reactive components of the acoustic intensity are used to investigate the structural features of the scattered field components. Numerical results are presented. The ability to extract scattered field features is illustrated with measurements obtained from a recent in-air experiment using an anechoic chamber and acoustic intensity probes to measure the scattered acoustic vector field from motionless rigid spheres.

Magnetic resonance imaging of hyperpolarized nuclei provides high image contrast with little or no background signal. To date, in-vivo applications of pre-hyperpolarized materials have been limited by relatively short nuclear spin relaxation times. Here, we investigate silicon nanoparticles as a new type of hyperpolarized magnetic resonance imaging agent. Nuclear spin relaxation times for a variety of Si nanoparticles are found to be remarkably long, ranging from many minutes to hours at room temperature, allowing hyperpolarized nanoparticles to be transported, administered, and imaged on practical time scales. Additionally, we demonstrate that Si nanoparticles can be surface functionalized using techniques common to other biologically targeted nanoparticle systems. These results suggest that Si nanoparticles can be used as a targetable, hyperpolarized magnetic resonance imaging agent with a large range of potential applications.

We report on a method to produce free-standing graphene sheets from epitaxial graphene on silicon carbide (SiC) substrate. Doubly clamped nanomechanical resonators with lengths up to 20 microm were patterned using this technique and their resonant motion was actuated and detected optically. Resonance frequencies of the order of tens of megahertz were measured for most devices, indicating that the resonators are much stiffer than expected for beams under no tension. Raman spectroscopy suggests that the graphene is not chemically modified during the release of the devices, demonstrating that the technique is a robust means of fabricating large-area suspended graphene structures.

Remote sensing of the environment has proved an invaluable tool to the study of animal ecology at continental to regional scales. Here, we investigated the utility of a remotely sensed index of plant productivity (the normalized difference vegetation index [NDVI]) at a much finer spatial scale to account for the range use of an omnivorous primate (the vervet monkey: Cercopithecus aethiops) foraging in a multipredator environment. Vervet monkey home range location suggested that the animals prefer areas with elevated productivity and reduced seasonality as indexed by simple NDVI metrics. Within the annual home range area, monthly NDVI values were linearly related to field measurements of leaf cover and quadratically associated with vervet monkey food availability. Temporal variation in parameters of local range use could subsequently be expressed in terms of local NDVI: Monthly averaged day journey length showed a second-order polynomial response, and the amount of time the monkeys spent on the ground increased with group size whereas linearly decreasing with monthly NDVI. The first finding signifies a behavioral response to food availability, whereas the latter is interpreted as an antipredatory response to changes in habitat visibility, associated with leaf cover. As a spatially explicit and temporally varying measure of habitat structure and productivity, the NDVI thus offers considerable scope for studies of animal behavioral ecology not only at broad spatiotemporal scales but also at a much finer grained level of analysis. Copyright 2009, Oxford University Press.

Purpose: To evaluate the safety of inferior vena cava (IVC) filter retrieval in therapeutically anticoagulated patients in comparison to prophylactically or not therapeutically anticoagulated patients with respect to retrieval-related hemorrhagic complications. Materials and methods: This was a retrospective study of 115 consecutive attempted IVC filter retrievals in 110 patients. Filter retrievals were stratified as performed in patients who were therapeutically anticoagulated (group 1), prophylactically anticoagulated (group 2), or not therapeutically anticoagulated (group 3). The collected data included anticoagulant and antiplatelet medications (type, form and duration of administration, dosage) at the time of retrieval. Phone interviews and chart review was performed for the international normalized ratio (INR), activated partial thromboplastin time, platelet count, infusion of blood products, and retrievalrelated hemorrhagic complications. Results: Group 1 included 65 attempted filter retrievals in 61 therapeutically anticoagulated patients by measured INR or dosing when receiving low-molecular-weight heparin (LMWH). Four retrievals were not successful. In patients receiving oral anticoagulation, the median INR was 2.35 (range, 2 to 8). Group 2 comprised 23 successful filter retrievals in 22 patients receiving a prophylactic dose of LMWH. Group 3 included 27 attempted filter retrievals in 27 patients not receiving therapeutic anticoagulation. Six retrievals were not successful. Five patients were receiving oral anticoagulation with a subtherapeutic INR (median, 1.49; range, 1.16 to 1.69). No anticoagulation medication was administered in 22 patients. In none of the groups were hemorrhagic complications related to the retrieval procedures identified. Conclusions: These results suggest that retrieval of vena cava filters in anticoagulated patients is safe. Interruption or reversal of anticoagulation for the retrieval of vena cava filters is not indicated. (CHEST 2007; 132:31–36)

Endoscopic surgical applications of erbium lasers have been limited due to the lack of a suitable mid-IR optical fiber delivery system. Germanium oxide fibers are used for noncontact tissue ablation, but are not recommended for contact tissue ablation applications typically required during endoscopic surgery. This study describes the assembly and characterization of hybrid mid-IR fibers consisting of germanium oxide trunk fibers and sapphire fiber tips, and side-firing germanium oxide fibers with either 45deg angled tips or micromirrors. Average powers up to 8.5 W (850 mJ at 10 Hz) and transmission up to 70% was demonstrated through 450-mum-core, 1.5-m-long fibers, sufficient for endoscopic laser ablation of soft and hard tissues in contact mode.

International audience; The vertical integration of graphene with inorganic semiconductors, oxide semiconductors, and newly emerging layered materials has recently been demonstrated as a promising route toward novel electronic and optoelectronic devices. Here, we report organic thin film transistors based on vertical heterojunctions of graphene and organic semiconductors. In these thin heterostructure devices, current modulation is accomplished by tuning of the injection barriers at the semiconductor/graphene interface with the application of a gate voltage. N-channel devices fabricated with a thin layer of C60 show a room temperature on/off ratio >104 and current density of up to 44 mAcm–2. Because of the ultrashort channel intrinsic to the vertical structure, the device is fully operational at a driving voltage of 200 mV. A complementary p-channel device is also investigated, and a logic inverter based on two complementary transistors is demonstrated. The vertical integration of graphene with organic semiconductors via simple, scalable, and low-temperature fabrication processes opens up new opportunities to realize flexible, transparent organic electronic, and optoelectronic devices.

Prenatal androgens are responsible for sex differences in behaviour and morphology in many species, causing changes in neural structure and function that persist throughout life. Some variation in the expression of behaviour between individuals of the same sex can also be attributed to differences in exposure to prenatal sex hormones. The ratio of the second and fourth digits (2D:4D ratio) is a proposed biomarker for prenatal androgen effects (PAE). Through assessment of 2D:4D ratios, this study aimed to investigate the relationship between inferred PAE and social behaviours in female chacma baboons (Papio ursinus). We validated a new method to measure 2D:4D indirectly using digital photographs and computer-assisted image analysis software. There was a strong correlation between 2D:4D ratio and dominance rank amongst female baboons. Low 2D:4D ratios were associated with high rank, lower submission rates and higher rates of non-contact and contact aggression. This is consistent with the hypothesis that prenatal androgens are linked to the expression of these behaviours in female baboons, although it was not possible to separate the effects of PAE and dominance rank on some rank-related behaviours. The 2D:4D ratio did not correlate with interest in infants or with the rate of affiliative behaviours, possibly because these behaviours are more affected by ovarian hormones in adult life than by PAE. Finally, mean 2D:4D ratios were positively correlated in six mother/infant pairs, consistent with a heritable basis for the 2D:4D ratio in primates. We suggest that PAE contribute significantly to the patterning of social relationships in female primates.

“Undoubtedly the most distinctive trait of the Primates, wherein this order contrasts with all other mammalian orders in its evolutionary history, is the tendency towards the development of a brain which is large in proportion to the total body weight, and which is particularly characterized by a relatively extensive and often richly convoluted cerebral cortex (p. 228).”1 While this statement is generally true, primate brains vary in size nearly one thousand-fold, from a mass of 1.8 g in the tiny mouse lemur to 1,300 g in modern humans. Many attempts have been made to understand both the distinctiveness of primate brains and the variation observed within the order: How did such variation evolve and why, and what are its cognitive implications? Following Jerison’s2 masterly review thirty years ago, comparative studies have highlighted suggestive correlations of brain size. However, the meaning and validity of these correlations have been vigorously debated. It has become clear that progress depends on taking great care in the use of comparative methods and in finding multiple converging strands of comparative evidence as opposed to making speculative interpretations of single correlations. In particular, recent work demonstrates the value of examining how evolutionary changes at different anatomical levels interrelate.

The hypothesis that play behavior is more prevalent in larger-brained animals has recently been challenged. It may be, for example, that only certain brain structures are related to play. Here, we analyze social play behavior with regards to the cerebellum: a structure strongly implicated in motor-development, and possibly also in cognitive skills. We present an evolutionary analysis of social play and the cerebellum, using a phylogenetic comparative method. Social play frequency and relative cerebellum size are positively correlated. Hence, there appears to be a link between the evolutionary elaboration of social play and the cerebellum.

The United States (US) Environmental Protection Agency (EPA) estimated that the use of technical grade pentachlorophenol (PCP) between 1970 and 1995 to treat wood was approximately 400 000 metric tons in the US, and that between 4800 and 36 000 g of 2,3,7,8-tetrachlorodibenzo- p -dioxin toxic equivalents (TEQs) were incorporated annually in treated wood. The EPA has been unable, however, to estimate the rate of release of polychlorinated dibenzo -p- dioxins and dibenzofurans (CDD/Fs) from treated utility poles into the environment. There is some evidence that CDD/Fs leach from treated poles into the surrounding soils, but these studies do not allow for the calculation of a rate of release from this mechanism. Another possible release mechanism is the volatilization of dioxins into the atmosphere, but there are no data to demonstrate, much less quantify, this release. While not directly measuring the release of dioxins from treated utility poles into the environment, this study was designed to examine the potential for such release. The general approach taken was to collect PCP-treated poles of varying ages, to remove and analyze multiple samples from each pole cross-section, and to compare the spatial distribution of CDD/F congeners among poles of different ages. Evidence of concentration–depth profile changes over time may provide insight into the potential for dioxins to migrate through and then out of PCP-treated utility poles. It was found that the CDD/F concentrations were consistently higher in the outer portions of the poles than the center. This trend tends to be most marked in older poles and for the lower chlorinated congeners. The trend for dioxins to concentrate in the outer portions of the pole over time suggest migration within the poles, and this migration may result in some environmental release. Other possible explanations were also offered.

Primate comparative anatomy is an established field that has made rich and substantial contributions to neuroscience. However, the labor-intensive techniques employed mean that most comparisons are often based on a small number of species, which limits the conclusions that can be drawn. In this review we explore how new developments in magnetic resonance imaging have the potential to apply comparative neuroscience to a much wider range of species, allowing it to realize an even greater potential. We discuss (1) new advances in the type of data that can be acquired, (2) novel methods for extracting meaningful measures from such data that can be compared between species, and (3) methods to analyse these measures within a phylogenetic framework. Taken together, these developments will allow researchers to characterize the relationship between different brains, the ecological niche they occupy, and the behavior they produce in more detail than ever before.

The vertical integration of graphene with inorganic semiconductors, oxide semiconductors, and newly emerging layered materials has recently been demonstrated as a promising route toward novel electronic and optoelectronic devices. Here, we report organic thin film transistors based on vertical heterojunctions of graphene and organic semiconductors. In these thin heterostructure devices, current modulation is accomplished by tuning of the injection barriers at the semiconductor/graphene interface with the application of a gate voltage. N-channel devices fabricated with a thin layer of C60 show a room temperature on/off ratio >104 and current density of up to 44 mAcm–2. Because of the ultrashort channel intrinsic to the vertical structure, the device is fully operational at a driving voltage of 200 mV. A complementary p-channel device is also investigated, and a logic inverter based on two complementary transistors is demonstrated. The vertical integration of graphene with organic semiconductors via simple,...

The enlargement of cetacean brain size represents an enigmatic event in mammalian evolution, yet its genetic basis remains poorly explored. One candidate gene associated with brain size evolution is the abnormal spindle-like microcephaly associated (ASPM), as mutations in this gene cause severe reductions in the cortical size of humans. Here, we investigated the ASPM gene in representative cetacean lineages and previously published sequences from other mammals to test whether the expansion of the cetacean brain matched adaptive ASPM evolution patterns. Our analyses yielded significant evidence of positive selection on the ASPM gene during cetacean evolution, especially for the Odontoceti and Delphinoidea lineages. These molecular patterns were associated with two major events of relative brain size enlargement in odontocetes and delphinoids. It is of particular interest to find that positive selection was restricted to cetaceans and primates, two distant lineages both characterized by a massive expansion of brain size. This result is suggestive of convergent molecular evolution, although no site-specific convergence at the amino acid level was found.

e apply time-resolved photoluminescence and ultrafast transient absorption spectroscopy to investigate the electron transfer between PbS nanocrystals and graphene. We find sub-ns decay times and we find strong evidence for a major contribution of charge transfer.

A well-known comparative biologist was once asked by a field biologist whether the latter’s detailed and painstaking field study of orangutan behavior, carried out over many years, qualified as an example of the comparative method. “No,” replied the comparative biologist, “that’s an anecdote.” The reply is somewhat harsh, as useful comparisons can be conducted both within and across species. The reply does emphasize, however, that analysis of patterns across species is fundamental to the study of adaptive evolution, particularly when variation needed to test hypotheses is present only at this interspecific level.1‐5 Examples in primatology include the occurrence of female sexual swellings in species with habitually multimale, rather than single-male, breeding systems,6,7 the relationship between polygynandrous mating and relatively large testes size,3,8 and the association between brain size and social group size.9 Thus, in many cases, interspecific variation is required to test adaptive hypotheses.10

A previously healthy 27-year-old woman (gravida 2 para 1) presented in the 42nd week of an otherwise ordinary pregnancy with right flank pain radiating to the groin. Membranes were intact, the cervix was long and closed, and no uterine contractions were present. Fundal height was appropriate (40 cm) and fetal assessment was unremarkable. She was afebrile with mild tachycardia (117 bpm) and was extremely tender in the right flank. Routine laboratory tests were within normal limits except for the urinalysis, which revealed 31 RBC. She was admitted to the labor and delivery unit for intravenous hydration with a presumed diagnosis of right renal colic. Within a few hours of admission, the flank pain evolved into generalized abdominal pain and physical examination revealed marked abdominal tenderness. Simultaneously, fetal heart tracings began to show ominous decelerations and loss of variability, prompting an emergency delivery for suspected placental abruption. In the operating room, a live male fetus weighing 7 lb 14 oz. was delivered by cesarean section (APGAR, 7/9). Placental abruption was not confirmed. Rather, inspection of the maternal abdomen revealed a hemoperitoneum of approximately 200 cm which was clotted and dark in color. A retroperitoneal hematoma was identified inferior to the liver which appeared to be the source of the intraperitoneal blood. No active bleeding was observed, so the abdomen was closed. However, her postoperative hematocrit level of 16.8% was lower than anticipated for the combined operative blood loss and hemoperitoneum (her hematocrit level on admission was 32.8%). A total of six units of blood were transfused postoperatively as the patient’s hematocrit level decreased on two further occasions. Computed tomography (CT) of the abdomen was performed to confirm the presence of a retroperitoneal hemorrhage on the right side as seen at surgery.

Studies of postconflict behavior have focused on Old World primates, particularly on members of the cercopithecines and chimpanzees. We present data on patterns of reconciliation in two captive groups of spectacled leaf monkeys, members of the Colobinae. Reconciliation occurred at a high rate relative to that in other primate species and within the first minute following a conflict. Friendly postconflict contact was usually initiated by aggressors in one group, and by recipients in the other. But, there was no difference in postconflict initiative to contact in comparison with MCs. These two groups showed behavioral specificity in the context of postconflict reunions. Ventroventral embracing was a common, explicit (de Waal, 1993) form of reconciliation. The intensity of aggression and situations in which the victim responded aggressively had no effect on the likelihood of reconciliation occurring. The postconflict behavior of both groups lends further support to the relationship-quality hypothesis (Aureli et al., 1989). Kinship and rank distance and had no effect on reconciliation, though affiliation levels correlated positively with the tendency to reconcile. These results indicate that spectacled langurs are among the more tolerant of the species studied so far.

We studied the postconflict interactions with group members other than the former opponent in two groups of spectacled leaf monkeys. We found no evidence of redirection of aggression towards other group members. Victims and aggressors sought affiliative contacts with uninvolved third parties. There was no evidence for consolation—affiliative contact initiated by an uninvolved third party, directed towards victims of aggression—in either group when all affiliative behaviors were considered. However, embracing was a characteristic first-contact interaction between individuals involved in aggression and third parties. This finding mirrors the results concerning reconciliation in spectacled leaf monkeys. Accordingly, embracing may be a true consolatory behavior in this species. When contacts with third parties occurred before or in the absence of reconciliation, the timing of such contacts fell within the time window during which reconciliation normally occurs. These contacts also resulted in affiliation levels twice that of baseline levels, supporting the idea that these contacts may function as a form of substitute reconciliation. We discuss these results in light of recent theories concerning postconflict behavior in primates.

At the most fundamental level, the size of an animal's home range is determined by its energy needs. In the absence of confounding variables, home range size should therefore scale with body mass according to Kleiber's exponent for metabolic rate of 0.75. Comparative studies in a wide range of taxa have failed to confirm this prediction: home range size has commonly been found to scale with an exponent significantly0.75. We develop a comparative measure of metabolic needs that incorporates both mass-specific metabolic rate and social-group size. We test the prediction that home range size in primates scales isometrically with this measure when an appropriate linear model is applied to data corrected for phylogenetic bias. Analyses using species values as data points indicate an exponent consistent with Kleiber's law. This result is misleading, however, because ecological factors confound the analysis, and the slopes within some ecologically homogeneous taxa are steeper. Accordingly, in analyses based on independent contrasts with reduced major axis, slopes are significantly greater than predicted by Kleiber's law. We examine the effects of other variables, and we find that systematic variation in substrate use, home range overlap, and diet account for the steeper than expected relationship between home range size and metabolic needs based on Kleiber's law. We therefore conclude that the scaling of home range size is subject to Kleiber's law but in combination with other factors. These results emphasize that the study of allometry requires detailed attention to statistical models and control of confounding variables.

The mammalian brain comprises a number of functionally distinct systems. It might therefore be expected that natural selection on particular behavioural capacities would have caused size changes selectively, in the systems mediating those capacities. It has been claimed, however, that developmental constraints limited such mosaic evolution, causing co-ordinated size change among individual brain components. Here we analyse comparative data to demonstrate that mosaic change has been an important factor in brain structure evolution. First, the neocortex shows about a fivefold difference in volume between primates and insectivores even after accounting for its scaling relationship with the rest of the brain. Second, brain structures with major anatomical and functional links evolved together independently of evolutionary change in other structures. This is true at the level of both basic brain subdivisions and more fine-grained functional systems. Hence, brain evolution in these groups involved complex relationships among individual brain components.

Today, VR research and development efforts often focus on the continual innovation of interaction styles and metaphors for virtual environments (VEs). New tools and interaction devices aim to increase the immersive experience rather than support seamless integration with real work scenarios. Even though users may soon perceive odours within VEs, real, task-oriented interaction within these environments will continue to lag behind. Combining these efforts can result in new user interfaces that reduce the cumbersome barriers prevalent in VEs today, finally unleashing the latent impact of this technology in everyday life. Implementing this vision requires an interdisciplinary and applied approach to integrate VR into the workplace. Mixed-reality display capabilities, useful multimodal interaction and perceptual, intuitive interfaces are major components of such an application-oriented and human-centered approach, for which we coined the term walk-up VR. The paper discusses augmented and virtual reality as contributing technologies.

Several theories have been proposed to explain the evolution of species differences in brain size, but no consensus has emerged. One unresolved question is whether brain size differences are a result of neural specializations or of biological constraints affecting the whole brain. Here I show that, among primates, brain size variation is associated with visual specialization. Primates with large brains for their body size have relatively expanded visual brain areas, including the primary visual cortex and lateral geniculate nucleus. Within the visual system, it is, in particular, one functionally specialized pathway upon which selection has acted: evolutionary changes in the number of neurons in parvocellular, but not magnocellular, layers of the lateral geniculate nucleus are correlated with changes in both brain size and ecological variables (diet and social group size). Given the known functions of the parvocellular pathway, these results suggest that the relatively large brains of frugivorous species are products of selection on the ability to perceive and select fruits using specific visual cues such as colour. The separate correlation between group size and visual brain evolution, on the other hand, may indicate the visual basis of social information processing in the primate brain.

An inadvertent case of pericardial placement of a central venous catheter was successfully treated by direct thrombin injection.

To prospectively evaluate the clinical efficacy of polyethylene-covered metallic Z-stents in treatment of dysphagia secondary to malignant esophageal obstruction and esophagorespiratory fistula.Thirty-five patients with dysphagia due to malignant esophageal obstruction (n = 32) and esophagorespiratory fistula (n = 3) were treated with polyethylene-covered Gianturco-Rösch Z-stents.Thirty-nine stents were placed in 35 patients. Stent placement was technically successful in all patients. Improvement in dysphagia was achieved in 34 of 35 patients. The average dysphagia score decreased from 3.1 (dysphagia to liquids) to 0.6 (essentially normal diet). An esophagorespiratory fistula was completely sealed in two of three patients. All 35 patients were followed up clinically at 1 day and 1 week and at 3-month intervals (range, 1 week to 18 1/2 months; mean, 4.8 months). Recurrent dysphagia or aspiration occurred in only three of 34 (9%) patients whose disease was initially palliated and was easily treated in all cases. Nine complications occurred in eight patients (23%) and included chest pain that required analgesia (n = 3), food impaction (n = 1), stent migration (n = 2), and upper gastrointestinal tract hemorrhage (n = 3).Polyethylene-covered stents are a relatively safe and effective means of long-term palliation in patients with severe malignant esophageal obstruction and esophagorespiratory fistula. These stents are easily deployed, and the rate of stent migration is relatively low.

We describe two cases of airway foreign bodies (FB) consisting of a dental crown. The shape and composition of dental crowns complicate their extraction from the tracheobronchial tree, sometimes necessitating thoracotomy. We describe the use of a multidisciplinary approach involving rigid and flexible bronchoscopy in concert with the use of wire snares under fluoroscopic guidance for extraction of these challenging FB. These cases illustrate that this multidisciplinary approach can allow successful extraction of the difficult FB from much of the tracheobronchial tree and the avoidance of thoracotomy.

Contrary to Smaers’s claim (1) that all recent studies find “allometric scaling of the human frontal lobe is not larger than expected,” one study (2) clearly claimed otherwise. Smaers’s own studies (3) are somewhat more ambiguous on this point, and he contradicts himself here by stating that “the conclusion that no aspects of the human frontal lobe are larger than expected (controlling for allometry) is not upheld.” It was such ambiguity that we sought to resolve in our report (4).

Resonant mechanics of high quality factor (Q) graphene coated silicon nitride devices have been explored using optical and electrical transduction schemes. With the addition of the graphene layer, we retain the desirable mechanical properties of silicon nitride but utilize the electrical and optical properties of graphene to transduce and tune the resonant motion by both optical and electrical means. By positioning the graphene-on-silicon-nitride drums in a tunable optical cavity, we observe position dependent damping and resonant frequency control of the devices due to optical absorption by graphene.

High stress stoichiometric silicon nitride resonators, whose quality factors exceed one million, have shown promise for applications in sensing and signal processing. Yet, electrical integration of the insulating silicon nitride resonators has been challenging, as depositing even a thin layer of metal degrades the quality factor significantly. In this work, we show that graphene used as a conductive coating for Si3N4 membranes reduces the quality factor by less than 30 % on average, which is minimal when compared to the effect of conventional metallization layers such as chromium or aluminum. The electrical integration of Si3N4-Graphene (SiNG) heterostructure resonators is demonstrated with electrical readout and electro-static tuning of the frequency by up to 1 % per volt. These studies demonstrate the feasibility of hybrid graphene/nitride mechanical resonators in which the electrical properties of graphene are combined with the superior mechanical performance of silicon nitride., 8 pages, 5 figures, journal

Predictions of the model of van Schaik (1989) of female-bonding in primates are tested by systematically comparing the ecology, level of within-group contest competition for food (WGC), and patterns of social behaviour found in two contrasting baboon populations. Significant differences were found in food distribution (percentage of the diet from clumped sources), feeding supplant rates and grooming patterns. In accord with the model, the tendencies of females to affiliate and form coalitions with one another, and to be philopatric, were strongest where ecological conditions promoted WGC. Group fission in the population with strong WGC was “horizontal” with respect to female dominance rank, and associated with female-female aggression during a period of elevated feeding competition. In contrast, where WGC was low, females’ grooming was focused on adult males rather than other females. Recent evidence suggests that group fission here is initiated by males, tends to result in the formation of one-male groups, and is not related to feeding competition but to male-male competition for mates. An ecological model of baboon social structure is presented which incorporates the effects of female-female competition, male-male competition, and predation pressure. The model potentially accounts for wide variability in group size, group structure and social relationships within the genus Papio. Socio-ecological convergence between common baboons and hamadryas baboons, however, may be limited in some respects by phylogenetic inertia.

Background: Mediastinal malignancies may involve the esophagus, leading to esophageal stenosis and dysphagia. Rigid and self-expanding esophageal stents have been used for effective palliation, but their use in extrinsic, compressive lesions is controversial. Methods: A retrospective review of self-expanding Gianturco-Rosch Z-stents that were successfully placed in 13 patients with malignant esophageal obstruction due to extrinsic lesions. Results: All patients had an improvement in dysphagia of at least two dysphagia grades. The mean dysphagia grade fell from 3.15 to 0.62. Mean survival was 2.2 months. Early (within 48 hours) procedure-related complications occurred in 4 of 13 patients and consisted of minor, transient chest pain that resolved within 6 hours (3 patients) and endoscopic stent dislodgment into the stomach (1 patient). Late complications (>48 hours) occurred in 2 patients and consisted of a partial proximal stent migration and the development of a benign stricture proximal to the stent. There was no procedural or stent related mortality. Conclusions: Esophageal obstruction and malignant dysphagia from extrinsic, compressive mediastinal malignancies can be effectively and safely palliated with self-expanding Gianturco-Rosch Z-stents. (Gastrointest Endosc 1996;43:483-9.)

The neocortex is widely held to have been the focus of mammalian brain evolution, but what selection pressures explain the observed diversity in its size and structure? Among primates, comparative studies suggest that neocortical evolution is related to the cognitive demands of sociality, and here I confirm that neocortex size and social group size are positively correlated once phylogenetic associations and overall brain size are taken into account. This association holds within haplorhine but not strepsirhine primates. In addition, the neocortex is larger in diurnal than in nocturnal primates, and among diurnal haplorhines its size is positively correlated with the degree of frugivory. These ecological correlates reflect the diverse sensory-cognitive functions of the neocortex.

Primates are distinguished by frontally directed, highly convergent orbits, which are associated with stereoscopic vision. Although stereoscopic vision requires specialized neural mechanisms, its implications for brain evolution are unknown. Using phylogenetic comparative analysis, I show that evolutionary increases among primate taxa in the degree of orbital convergence correlate with expansion of visual brain structures and, as a consequence, with the overall size of the brain. This pattern is found across the whole primate order and is also repeated within each of the two major primate subtaxa. The visual expansion associated with increased binocularity is specific to the parvocellular visual pathway, consistent with recent evidence implicating this pathway in fine-grained stereopsis. The results support the hypothesis that brain size evolution in primates was associated with visual specialization.

Purpose To evaluate expandable metallic Gianturco-Rosch Z (GRZ) stents for treatment of benign and malignant tracheobronchial stenoses. Patients and Methods Six patients, ages 45–73 years, were treated for severe dyspnea with placement of GRZ stents. Three patients had benign tracheal lesions (one tracheomalacia, two postoperative) and received uncovered GRZ stents. Three patients had malignant stenoses at the level of the carina; one received an uncovered stent and the other two received silicone-covered GRZ stents. Results Two patients with benign lesions responded well to stent placement. One was asymptomatic for a year and then was lost to follow-up; the other improved substantially but died of end-stage lung disease 5 months after stent placement. A third patient with a benign high tracheal lesion did poorly; symptoms recurred secondary to inferior migration of a stent, which was removed surgically at 4 months. All patients with malignant lesions improved symptomatically after stent placement and remained without significant dyspnea until death (from 1 to 6 months). Conclusion Expandable GRZ stents are promising devices for treatment of benign lesions and offer effective palliation of malignant tracheobronchial stenoses.

How brains have evolved in response to particular selection pressures is illuminated by ecological correlates of differences in brain structure among contemporary species. The focus of most comparative studies has been on the overall size of brains relative to body size, hence ignoring the ways in which selection operates on specific neural systems. Here we investigate evolutionary radiations in the size of visual and olfactory brain structures within three orders of mammals: primates, bats and insectivores. The comparative relationships within these three orders show both similarities and differences. After removal of the allometric effect of overall brain size, the sizes of different structures within each sensory modality are positively correlated in all three orders. Correlations between visual and olfactory structures, however, are negative in primates, negative but non-significant in insectivores, and positive in bats. In both primates and insectivores, nocturnal lineages tend to have larger olfactory structures than do diurnal or partly diurnal lineages, and among the primates diurnal lineages have larger striate visual cortexes. Hence the apparent trade-off between vision and olfaction in primates seems to be related to the divergence of nocturnal and diurnal forms. However, negative correlations between visual and olfactory structures were also found when nocturnal strepsirhines and diurnal haplorhines were analysed separately, suggesting that ecological variables in addition to activity timing may be significant. Indeed, there were also associations with diet: frugivory was associated with enlargements of the geniculostriate visual system in diurnal primates, enlargements of olfactory structures in nocturnal primates, and possibly enlargements of both in bats. Further ecological associations were found within insectivores: aquatic lineages had smaller olfactory structures than in their non-aquatic counterparts, and fossorial lineages had smaller optic nerves than in non-fossorial forms. We conclude that activity timing, diet and habitat have each played a role in the evolutionary radiation of mammalian sensory systems, but with varying effects in the different taxa. Some of the associations between ecology and sensory systems suggest alternative explanations for correlates of overall brain size, which have in the past commonly been interpreted in terms of selection on intelligence.

The many different diverse methods and models of neuroscience are aimed at answering basic questions such as: what are brains for? How are they organised? and How does this organisation support adaptive behaviour? A key biological fact to bear in mind in constructing answers to those questions is that brains have evolved. The key point that this article emphasises, however, is that understanding species differences in cognitive mechanisms requires a close relationship between evolutionary biology and cognitive neuroscience. The distinctive cognitive attributes of primates, including humans, are widely assumed to relate in some way to their large brains. The key point is this: the intellect of an animal cannot be entirely isolated from the rest of its biology. However, to some extent, all experiments carried out in the laboratory are attempts to do precisely that, in that the point of experiments is to isolate a phenomenon of interest by controlling confounding variables.

By virtue of their low mass and stiffness, atomically thin mechanical resonators are attractive candidates for use in optomechanics. Here, we demonstrate photothermal back-action in a graphene mechanical resonator comprising one end of a Fabry–Perot cavity. As a demonstration of the utility of this effect, we show that a continuous wave laser can be used to cool a graphene vibrational mode or to power a graphene-based tunable frequency oscillator. Owing to graphene’s high thermal conductivity and optical absorption, photothermal optomechanics is efficient in graphene and could ultimately enable laser cooling to the quantum ground state or applications such as photonic signal processing.

We demonstrate THz imaging and time-domain spectroscopy of a single-layer graphene film. The large-area graphene was grown by chemical vapor deposition on Cu-foil and subsequently transferred to a Si substrate. We took a transmission image of the graphene/Si sample measured by a Si:bolometer (pixel size is 0.4-mm). The graphene film (transmission: 36 - 41%) is clearly resolved against the background of the Si substrate (average transmission: 56.6%). The strong THz absorption by the graphene layer indicates that THz carrier dynamics are dominated by intraband transitions. A theoretical analysis based on the Fresnel coefficients for a metallic thin film shows that the local sheet resistance varies across the sample from 420 to 590 Ohm, consistent with electron mobility ~ 3,000 cm 2 V -1 s -1 . We also measured time-resolved THz waveforms through the Si substrate and the graphene/Si sample. The waveforms consist of a series of single-cycle THz pulses: a directly transmitted pulse, then subsequent "echos" corresponding to multiple reflections from the substrate. The amplitude difference between graphene/Si pulses and Si pulses becomes more pronounced as the pulses undergo more reflections. From these measurements, we obtained spectrally flat transmission spectra of the transmitted pulses and the average sheet resistance 480 Ohm, consistent with the results of the power transmission measurement. The flat spectral responses indicate that the carrier scattering time in our graphene sample is much shorter than the THz pulse duration.

THz imaging and spectroscopy using broadband THz pulses map out the THz carrier dynamics of large-area single-layer graphene. Non-contacting, non-destructive THz probing reveals the local sheet conductivity of the graphene samples.