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Corals offer a rich archive of past climate variability in tropical ocean regions where instrumental data are limited and where our knowledge of multi-decadal climate sensitivity is incomplete. In the eastern equatorial Pacific, coral isotopic records track variations in ENSO-related changes in sea-surface temperature; further west, corals record variability in sea-surface temperature and rainfall that accompanies zonal displacement of the Indonesian Low during ENSO events. These multi-century records reveal previously unrecognised ENSO variability on time scales of decades to centuries. Outside the ENSO-sensitive equatorial Pacific, long-term trends towards recent warmer/wetter conditions suggest the tropics respond to global forcings. New coral paleothermometers indicate that surface-ocean temperatures in the tropical southwestern Pacific were depressed by 4-6°C during the Younger Dryas climatic event and rose episodically during the next 4000 yr. High temporal-resolution measurements of Sr/Ca and δ18O in corals provide information about the surface-ocean hydrologic balance and can resolve the seasonal balance between precipitation and evaporation. Radiocarbon measurements in corals, coupled with ocean circulation models, may be used to reconstruct near-surface ocean circulation, past mixing rates, and the distribution of fossil fuel CO2 in the upper ocean. Most recently, seasonal to interannual variations in the radiocarbon of corals from the equatorial Pacific have been linked to the redistribution of surface waters associated with the ENSO.

Paired carbon-14 ((14)C) and thorium-230((230)Th) ages were determined on fossil corals from the Huon Peninsula, Papua New Guinea. The ages were used to calibrate part of the (14)C time scale and to estimate rates of sea-level rise during the last deglaciation. An abrupt offset between the (14)C and (230)Th ages suggests that the atmospheric (14)C/(12)C ratio dropped by 15 percent during the latter part of and after the Younger Dryas (YD). This prominent drop coincides with greatly reduced rates of sea-level rise. Reduction of melting because of cooler conditions during the YD may have caused an increase in the rate of ocean ventilation, which caused the atmospheric (14)C/(12)C ratio to fall. The record of sea-level rise also shows that globally averaged rates of melting were relatively high at the beginning of the YD. Thus, these measurements satisfy one of the conditions required by the hypothesis that the diversion of meltwater from the Mississippi to the St. Lawrence River triggered the YD event.

Employees often have a great deal of work to accomplish within stringent deadlines. Therefore, employees may engage in shortcut behaviors, which involve eschewing standard procedures during goal pursuit to save time. However, shortcuts can lead to negative consequences such as poor-quality work, accidents, and even large-scale disasters. Despite these implications, few studies have investigated the antecedents of shortcut behaviors. In this research, we propose that employees engage in shortcut behaviors to regulate their velocity (i.e., rate of progress). Specifically, we predict that when individuals experience slower-than-referent velocity, they will (a) believe that the goal is unlikely to be met via standard procedures and (b) experience feelings of frustration. In turn, we expect these psychological states to be related to the perceived utility of shortcuts, especially when shortcuts are perceived as viable means to achieve the goal. Finally, we predict that the perceived utility of shortcuts will be positively related to actual shortcut behaviors. We tested these predictions using a laboratory experiment in which we manipulated velocity and unobtrusively observed shortcuts (Study 1, N = 147), as well as a daily diary study in which employees reported their velocity and shortcut behaviors over 5 consecutive workdays (Study 2, N = 395). Both studies provided support for our predictions. In sum, this research provides evidence to suggest that the experience of slow progress can lead to shortcuts not only by casting doubt on employees' perceived likelihood of meeting the goal but also by producing feelings of frustration. (PsycInfo Database Record (c) 2023 APA, all rights reserved).

Although breaks can help employees stay energized and maintain high levels of performance throughout the day, employees sometimes refrain from taking a break despite wanting to do so. Unfortunately, few studies have investigated individuals' reasons for taking and for not taking a break at work. To address this gap, we developed a model for predicting employees' break-taking behaviors. We developed hypotheses by integrating theories of work stress, self-regulation, and the results of a qualitative survey conducted as part of the current research (Study 1). Specifically, we predicted that high workloads would be positively related to the desire to detach from work, but that at the same time, high workloads would also deter employees from actually taking breaks. Furthermore, we predicted that employees would be less likely to act upon their desire to take a break within an environment where breaks are frowned upon by supervisors and coworkers, relative to an environment where breaks are allowed and encouraged. The results of a daily diary study of full-time employees (Study 2) provided general support for these predictions. Altogether, this research provides insights into the manner in which employees' psychological experiences and characteristics of the work environment combine to predict break-taking., Supplementary Information: The online version contains supplementary material available at 10.1007/s10869-022-09866-4., Competing Interests: Conflict of InterestThe authors declare that they have no conflict of interest., (© The Author(s), under exclusive licence to Springer Science+Business Media, LLC, part of Springer Nature 2022, Springer Nature or its licensor (e.g. a society or other partner) holds exclusive rights to this article under a publishing agreement with the author(s) or other rightsholder(s); author self-archiving of the accepted manuscript version of this article is solely governed by the terms of such publishing agreement and applicable law.)

Individuals who contract Covid-19 often experience problems with memory, attention, and concentration, even after recovering from the initial illness. In the current manuscript, we argue that these symptoms are likely to manifest as cognitive failures in the workplace. Downstream, cognitive failures were expected to be associated with decreased task performance and increased turnover intentions. We collected data from a sample of working adults who either had (n = 45) or had not (n = 49) contracted Covid-19 at least one month prior to the study. Both groups were matched on key demographic characteristics. As anticipated, individuals who had contracted Covid-19 reported significantly more cognitive failures at work, relative to individuals who did not. More so, having contracted Covid-19 had significant indirect effects on task performance and turnover intentions via cognitive failure. These results indicate that beyond physical harm, Covid-19 can also have a detrimental influence on an individual's capacity to perform at work., (© 2022. The Author(s).)

Effective risk communication during the COVID-19 pandemic is critical for encouraging appropriate public health behaviors. One way that the public is informed about COVID-19 numbers is through reports of daily new cases. However, presenting daily cases has the potential to lead to a dynamic reasoning bias that stems from intuitive misunderstandings of accumulation. Previous work in system dynamics shows that even highly educated individuals with training in science and math misunderstand basic concepts of accumulation. In the context of COVID-19, relying on the single cue of daily new cases can lead to relaxed attitudes about the risk of COVID-19 when daily new cases begin to decline. This situation is at the very point when risk is highest because even though daily new cases have declined, the active number of cases are highest because they have been accumulating over time. In an experiment with young adults from the USA and Canada (N = 551), we confirm that individuals fail to understand accumulation regarding COVID-19, have less concern regarding COVID-19, and decrease endorsement for public health measures as new cases decline but when active cases are at the highest point. Moreover, we experimentally manipulate different dynamic data visualizations and show that presenting data highlighting active cases and minimizing new cases led to increased concern and increased endorsement for COVID-19 health measures compared to a control condition highlighting daily cases. These results hold regardless of country, political affiliation, and individual differences in decision making. This study has implications for communicating the risks of contracting COVID-19 and future public health issues., (© 2021. The Author(s).)

To achieve long-term goals, individuals, teams, and organizations must engage in numerous short-term performance episodes. This creates a trade-off between proximal and distal performance. On the one hand, allocating resources toward an episode typically facilitates performance in that episode, thereby contributing to distal success. On the other hand, allocating resources to one episode leaves fewer resources for subsequent episodes, thereby inhibiting distal success. We drew upon self-regulatory theories to predict that the trade-off between proximal and distal concerns is managed by allocating resources according to the demands of the situation. Specifically, we predicted that the tendency to allocate resources according to goal-performance discrepancies would improve distal performance. We tested our hypotheses using data from 5 National Hockey League (NHL) seasons. As expected, NHL teams used goal-performance discrepancies to allocate a key resource-playing time of their most valuable players. More importantly, between-team variance in resource allocation strategy accounted for significant variance in distal performance (end of season record). These results provide evidence that strategic reductions in resource allocation to proximal performance episodes is a fundamental self-regulatory process necessary for facilitating long-term success. (PsycINFO Database Record (c) 2019 APA, all rights reserved).

Cosmogenic 10 Be flux from the atmosphere is a proxy for rainfall. Using this proxy, we derived a 550,000-year-long record of East Asian summer monsoon (EASM) rainfall from Chinese loess. This record is forced at orbital precession frequencies, with higher rainfall observed during Northern Hemisphere summer insolation maxima, although this response is damped during cold interstadials. The 10 Be monsoon rainfall proxy is also highly correlated with global ice-volume variations, which differs from Chinese cave δ 18 O, which is only weakly correlated. We argue that both EASM intensity and Chinese cave δ 18 O are not governed by high-northern-latitude insolation, as suggested by others, but rather by low-latitude interhemispheric insolation gradients, which may also strongly influence global ice volume via monsoon dynamics., (Copyright © 2018 The Authors, some rights reserved; exclusive licensee American Association for the Advancement of Science. No claim to original U.S. Government Works.)

Disturbances are factors outside of a person's control that influence goal progress. Although disturbances are typically included in theoretical accounts of goal pursuit, relatively little empirical research has explicitly considered the effects of disturbances on the goal-striving process. We address this gap in the literature by examining the effects that disturbances have on the emotional experience of goal pursuit. More importantly, we differentiate between distance disturbances (changes to the amount of progress made) and velocity disturbances (changes to the rate of progress made). We conducted 2 experiments (N = 62 and N = 134) in which participants completed work simulation tasks to earn a $5.00 reward. Partway through the experiment participants' progress was inhibited by either a distance disturbance or a velocity disturbance. Importantly, the distance and velocity disturbances were equated in terms of their influence on the likelihood of obtaining the cash prize. In both studies the introduction of a disturbance decreased enthusiasm and increased frustration. However, over time the effects of distance and velocity disturbances on enthusiasm and frustration diverged. Specifically, the velocity disturbance had a more enduring effect on these emotions, relative to the distance disturbance. Downstream, in Study 1 enthusiasm positively predicted goal commitment. In Study 2 enthusiasm positively predicted goal commitment, effort, and task performance. Likewise, in Study 2 frustration negatively predicted goal commitment and task performance. Therefore, relative to distance disturbances, velocity disturbances appear to be more disruptive to goal pursuit. We discuss theoretical implications and practical implications for managing employee motivation. (PsycINFO Database Record, ((c) 2017 APA, all rights reserved).)

Goal orientations-the degree to which individuals are concerned with developing new skills, demonstrating already developed skills, and avoiding appearing foolish or incompetent-have been repeatedly shown to be important individual difference variables for performance across a range of contexts. In the current study, we identified perceptions of time pressure as a predictor of state goal orientations. Specifically, we posited that developing new skills may be conceived of as somewhat of a luxury-that is, mastery-oriented behaviors-are more likely to emerge when one is not under time pressure. On the other hand, when perceptions of time pressure increase, we expected individuals to be less willing to invest in development and instead to adopt more avoidant goals. Support for these predictions was found in a sample of undergraduate statistics students who were followed over the course of a 15-week academic semester. Specifically, perceptions of time pressure were negatively related to state mastery goal orientation and positively related to state performance-avoid goal orientation. Also, state goal orientations mediated the relationship between time pressure and performance. We conclude with a discussion of the implications of our results for motivational theory as well as how organizations can use the current results to mitigate the potentially detrimental effects of time pressure on performance.

Although persistent drought in West Africa is well documented from the instrumental record and has been primarily attributed to changing Atlantic sea surface temperatures, little is known about the length, severity, and origin of drought before the 20th century. We combined geomorphic, isotopic, and geochemical evidence from the sediments of Lake Bosumtwi, Ghana, to reconstruct natural variability in the African monsoon over the past three millennia. We find that intervals of severe drought lasting for periods ranging from decades to centuries are characteristic of the monsoon and are linked to natural variations in Atlantic temperatures. Thus the severe drought of recent decades is not anomalous in the context of the past three millennia, indicating that the monsoon is capable of longer and more severe future droughts.

The chemical mechanisms underlying the growth of cave formations such as stalactites are well known, yet no theory has yet been proposed which successfully accounts for the dynamic evolution of their shapes. Here we consider the interplay of thin-film fluid dynamics, calcium carbonate chemistry, and CO2 transport in the cave to show that stalactites evolve according to a novel local geometric growth law which exhibits extreme amplification at the tip as a consequence of the locally-varying fluid layer thickness. Studies of this model show that a broad class of initial conditions is attracted to an ideal shape which is strikingly close to a statistical average of natural stalactites.

During the Younger Dryas event, about 12,000 years ago, the Northern Hemisphere cooled by between 2 and 10 degrees C (refs 1, 2) whereas East Antarctica experienced warming. But the spatial signature of the event in the southern mid-latitudes and tropics is less well known, as records are sparse and inconclusive. Here we present high-resolution analyses of skeletal Sr/Ca and 18O/16O ratios for a giant fossil Diploastrea heliopora coral that was preserved in growth position on the raised reef terraces of Espiritu Santo Island, Vanuatu, in the southwestern tropical Pacific Ocean. Our data indicate that sea surface temperatures in Vanuatu were on average 4.5 +/- 1.3 degrees C cooler during the Younger Dryas event than today, with a significant interdecadal modulation. The amplified annual cycle of sea surface temperatures, relative to today, indicates that cooling was caused by the compression of tropical waters towards the Equator. The positive correlation in our record between the oxygen isotope ratios of sea water and sea surface temperatures suggests that the South Pacific convergence zone, which brings 18O-depleted precipitation to the area today, was not active during the Younger Dryas period.

There are many diverse uses of accelerator mass spectrometry (AMS). Carbon-14 studies at our laboratory include much research related to paleoclimate, both with 14C as a tracer of past changes in environmental conditions as observed in corals, marine sediments and many terrestrial records. Terrestrial records such as forest fires can also show the influence of oceanic oscillations, whether they are short-term such as ENSO, or on the millennial time scale. In tracer applications, we have developed the use of 129I as well as 14C as tracers for nuclear pollution studies around radioactive waste dump sites, in collaboration with IAEA. We discuss some applications carried out in Tucson for several of these fields and hope to give some idea of the breadth of these studies.

There are many diverse uses of accelerator mass spectrometry (AMS). 14C studies at our laboratory include much research related to paleoclimate, with 14C as a tracer of past changes in environmental conditions as observed in corals, marine sediments, and many terrestrial records. Terrestrial records can also show the influence of oceanic oscillations, whether they are short term, such as ENSO (El Niño/Southern Oscillation), or on the millennial time scale. In tracer applications, we have developed the use of 129I as well as 14C as tracers for nuclear pollution studies around radioactive waste dump sites, in collaboration with IAEA. We discuss some applications carried out in Tucson, AZ, for several of these fields and hope to give some idea of the breadth of these studies.

A long record of atmospheric 14C concentration, from 45 to 11 thousand years ago (ka), was obtained from a stalagmite with thermal-ionization mass-spectrometric 230Th and accelerator mass-spectrometric 14C measurements. This record reveals highly elevated Delta14C between 45 and 33 ka, portions of which may correlate with peaks in cosmogenic 36Cl and 10Be isotopes observed in polar ice cores. Superimposed on this broad peak of Delta14C are several rapid excursions, the largest of which occurs between 44.3 and 43.3 ka. Between 26 and 11 ka, atmospheric Delta14C decreased from approximately 700 to approximately 100 per mil, modulated by numerous minor excursions. Carbon cycle models suggest that the major features of this record cannot be produced with solar or terrestrial magnetic field modulation alone but also require substantial fluctuations in the carbon cycle.

Stepped-heating experiments on martian meteorites Allan Hills 84001 (ALH84001) and Elephant Moraine 79001 (EETA79001) revealed low-temperature (200 to 430 degrees Celsius) fractions with a carbon isotopic composition delta13C between -22 and -33 per mil and a carbon-14 content that is 40 to 60 percent of that of modern terrestrial carbon, consistent with a terrestrial origin for most of the organic material. Intermediate-temperature (400 to 600 degrees Celsius) carbonate-rich fractions of ALH84001 have delta13C of +32 to +40 per mil with a low carbon-14 content, consistent with an extraterrestrial origin, whereas some of the carbonate fraction of EETA79001 is terrestrial. In addition, ALH84001 contains a small preterrestrial carbon component of unknown origin that combusts at intermediate temperatures. This component is likely a residual acid-insoluble carbonate or a more refractory organic phase.

Seasonal records of tropical sea-surface temperature (SST) over the past 10(5) years can be recovered from high-precision measurements of coral strontium/calcium ratios with the use of thermal ionization mass spectrometry. The temperature dependence of these ratios was calibrated with corals collected at SST recording stations and by (18)O/(16)O thermometry. The results suggest that mean monthly SST may be determined with an apparent accuracy of better than 0.5 degrees C. Measurements on a fossil coral indicate that 10,200 years ago mean annual SSTs near Vanuatu in the southwestern Pacific Ocean were about 5 degrees C colder than today and that seasonal variations in SST were larger. These data suggest that tropical climate zones were compressed toward the equator during deglaciation.

A Monte Carlo program has been devised that estimates the total absorbed energy and mean dose in defined regions within phantoms exposed to rotating x-ray sources. The calculations deal with fanlike beams of rectangular cross section projected onto elliptic cylindrical phantoms, which may be inhomogeneous. The effects of coherent scattering, which may be significant in a narrow-beam geometry, can be studied. The code can score the exit flux, allowing study of the relationship between dose and image quality. The model is described, the code is verified, and typical results are presented.

Computed tomography potentially offers the most accurate noninvasive means of estimating in vivo volumes. Contiguous 1-cm-thick CT scans were obtained through phantoms, dog kidneys in vivo, and human spleens before splenectomy. Cross-sectional areas were calculated for each individual scan and volumes then determined with each of four mathematical integration techniques. Volume estimations were compared to volumes determined by water displacement. The simplest, most practical means of calculating volumes, using the summation-of-areas technique with scans obtained at 2 cm intervals, was similar in accuracy to more complex methods. The mean percentage error of volume calculations using the sum-of-areas technique was 4.95% for five immobile phantoms, 3.86% for eight dog kidneys, 3.59% for eight human spleens in vivo at 1 cm scan spacing, and 3.65% for the same human spleens at 2 cm scan spacings. Difficulties in visual recognition and manual tracking of object boundaries seem to be more significant sources of error than patient-related factors.

Transmission computed tomography (CT) was used to study the global and regional density changes in the dog lung associated with oleic acid induced lung injury. The same level of the lower thorax was scanned (5 s/scan) during suspended ventilation at functional residual capacity prior to and after oleic acid infusion (0.05 ml/kg) into the right atrium. The first signs of edema were usually seen within 15 to 30 min after oleic acid infusion and consisted of patchy areas of increased density primarily in the peripheral and dependent zones. Mean CT density (Hounsfield units + 1,000) of lung cross sections from five dogs was 198 +/- 9 (SEM) during base line; density significantly (p less than 0.05) increased to 243 +/- 14 30 min after infusion and reached an apparent plateau of 294 +/- 31 75 min after oleic acid infusion. Thermal-dye dilution measurements indicated that extravascular lung water increased by 3.8 ml/kg from base line to 75 min after oleic acid infusion.

A method is presented for calculating a background image to be subtracted from TI-201 myocardial perfusion images. The method was derived from experimental measurements of background components in which hearts of animals injected with TI-201 were replaced with hearts from nonradioactive animals. The algorithm generates a background image that accounts for TI-201 activity in surrounding tissues and within the cardiac chamber. Comparison of the computer-generated background images with background images of the experimental models showed a mean difference of about 3% (range 1-6%). Clinical images using this method of background generation and subtraction are presented.

Extracting density information from irregularly shaped tissue areas of CT scans requires automated methods when many scans are involved. We describe two computer methods that automatically isolate the lung area of a CT scan. Each starts from a single, operator specified point in the lung. The first method follows the steep density gradient boundary between lung and adjacent tissues; this tracking method is useful for estimating the overall density and total area of lung in a scan because all pixels within the lung area are available for statistical sampling. The second method finds all contiguous pixels of lung that are within the CT number range of air to water and are not a part of strong density gradient edges; this method is useful for estimating density and area of the lung parenchyma. Structures within the lung area that are surrounded by strong density gradient edges, such as large blood vessels, airways and nodules, are excluded from the lung sample while lung areas with diffuse borders, such as an area of mild or moderate edema, are retained. Both methods were tested on scans from an animal model of pulmonary edema and were found to be effective in isolating normal and diseased lungs. These methods are also suitable for isolating other organ areas of CT scans that are bounded by density gradient edges.

A shock model was used to explore the capability of computed tomography (CT) to detect changes in lung density during hypovolemia and after resuscitation. The same level of the lower thorax was scanned repeatedly during base-line, shock (aortic pressure 60 mmHg), and after resuscitation with shed blood. The average baseline CT number (+/- SEM) for 5 areas of interest for four prone dogs was -754 +/- 16 (air = -1000, water = 0). This decreased 7.4% to -810 +/- 15 (P less than .05) during shock. After resuscitation CT density was -773 +/- 17 or 2.5% less than baseline (P greater than .1). A dorsal to ventral gradient of increasing CT density during baseline was maintained in all five areas during shock and post-resuscitation. From baseline to shock there were also significant changes in heart rate, mean aortic pressure, cardiac output, and vascular volume. Extravascular lung volume after resuscitation was equal to baseline volume. We conclude that CT is sufficiently sensitive to detect rapid physiological changes leading to increased or decreased lung density.

This paper reviews the signal-to-noise considerations of optical beam reading processes. It shows that, with a binary light signal system using level detection, it is preferable to consider the arithmetic sum of the noise terms of each level as the noise term in a signal-to-noise calculation, even though the sum of the gaussian noise terms for each separate level are summed as powers. For the case where gaussian and nongaussian noise terms are combined for one level, it is preferable to add the peak values of their envelopes rather than employ rms values. The importance of the magnitude of the common mode rejection ratio, when deciding whether or not to employ a differential light detection system, is considered. The specific case of a magnetooptical material that exhibits Faraday rotation is used to illustrate these points in a quantitative fashion.