196 research outputs found
From Prestellar to Protostellar Cores II. Time Dependence and Deuterium Fractionation
We investigate the molecular evolution and D/H abundance ratios that develop
as star formation proceeds from a dense-cloud core to a protostellar core, by
solving a gas-grain reaction network applied to a 1-D radiative hydrodynamic
model with infalling fluid parcels. Spatial distributions of gas and ice-mantle
species are calculated at the first-core stage, and at times after the birth of
a protostar. Gas-phase methanol and methane are more abundant than CO at radii
AU in the first-core stage, but gradually decrease with time,
while abundances of larger organic species increase. The warm-up phase, when
complex organic molecules are efficiently formed, is longer-lived for those
fluid parcels in-falling at later stages. The formation of unsaturated carbon
chains (warm carbon-chain chemistry) is also more effective in later stages;
C, which reacts with CH to form carbon chains, increases in abundance
as the envelope density decreases. The large organic molecules and carbon
chains are strongly deuterated, mainly due to high D/H ratios in the parent
molecules, determined in the cold phase. We also extend our model to simulate
simply the chemistry in circumstellar disks, by suspending the 1-D infall of a
fluid parcel at constant disk radii. The species CHOCH and HCOOCH
increase in abundance in yr at the fixed warm temperature; both
also have high D/H ratios.Comment: accepted to ApJ. 55 pages, 7 figures, 3 table
Size-Weight Illusion: A Proof of Concept
Hypotheses
- SWI will be present in full body squat with more force being produced through the lower extremity on the side that has the larger cube initially, with more vertical displacement of the large cube side as well
- Pre lift predictions will bias the larger cube, while post predictions will bias the smaller cube
- We also anticipate a larger vertical displacement on the side with the larger box following the fatigue protoco
A consensus on the use of daylight photodynamic therapy in the UK
Background: Actinic keratoses (AKs) are a consequence of chronic exposure to ultraviolet radiation. Treatment of chronically photo-damaged skin and AKs is driven by risk of progression to squamous cell carcinoma, as well as for symptomatic relief. Conventional photodynamic therapy (c-PDT) is indicated when AKs are multiple or confluent and if patients respond poorly or are unable to tolerate other therapies. c-PDT is limited by the field size that can be treated in single sessions and can cause significant discomfort.Objective: Recent studies investigated daylight illumination to activate protoporphyrin IX and daylight-PDT (d-PDT) is now licensed in the UK for face and scalp AKs. A group of experts met to discuss application of d-PDT with methyl aminolevulinate (MAL) and develop a UK consensus statement, specific to UK weather conditions.Methods: The UK consensus recommendations were reached among eight experts, who reviewed recent studies on d-PDT, assessed UK meteorological data and discussed personal experiences of d-PDT for AKs.Results: Recommendations from these discussions provide guidance on d-PDT use, specifically regarding patient selection, therapeutic indications, when to treat, skin preparation, MAL application and daylight exposure for patients with AKs.Conclusions: This UK expert consensus provides practical guidance for UK application of d-PDT
Sequential Effects in Judgements of Attractiveness: The Influences of Face Race and Sex
In perceptual decision-making, a personâs response on a given trial is influenced by their response on the immediately preceding trial. This sequential effect was initially demonstrated in psychophysical tasks, but has now been found in more complex, real-world judgements. The similarity of the current and previous stimuli determines the nature of the effect, with more similar items producing assimilation in judgements, while less similarity can cause a contrast effect. Previous research found assimilation in ratings of facial attractiveness, and here, we investigated whether this effect is influenced by the social categories of the faces presented. Over three experiments, participants rated the attractiveness of own- (White) and other-race (Chinese) faces of both sexes that appeared successively. Through blocking trials by race (Experiment 1), sex (Experiment 2), or both dimensions (Experiment 3), we could examine how sequential judgements were altered by the salience of different social categories in face sequences. For sequences that varied in sex alone, own-race faces showed significantly less opposite-sex assimilation (male and female faces perceived as dissimilar), while other-race faces showed equal assimilation for opposite- and same-sex sequences (male and female faces were not differentiated). For sequences that varied in race alone, categorisation by race resulted in no opposite-race assimilation for either sex of face (White and Chinese faces perceived as dissimilar). For sequences that varied in both race and sex, same-category assimilation was significantly greater than opposite-category. Our results suggest that the race of a face represents a superordinate category relative to sex. These findings demonstrate the importance of social categories when considering sequential judgements of faces, and also highlight a novel approach for investigating how multiple social dimensions interact during decision-making
Stress, stressâinduced cortisol responses, and eyewitness identification performance
In the eyewitness identification literature, stress and arousal at the time of encoding are considered to adversely influence identification performance. This assumption is in contrast with findings from the neurobiology field of learning and memory, showing that stress and stress hormones are critically involved in forming enduring memories. This discrepancy may be related to methodological differences between the two fields of research, such as the tendency for immediate testing or the use of very short (1-2 hours) retention intervals in eyewitness research, while neurobiology studies insert at least 24 hours. Other differences refer to the extent to which stress-responsive systems (i.e., the hypothalamic-pituitary-adrenal axis) are stimulated effectively under laboratory conditions. The aim of the current study was to conduct an experiment that accounts for the contemporary state of knowledge in both fields. In all, 123 participants witnessed a live staged theft while being exposed to a laboratory stressor that reliably elicits autonomic and glucocorticoid stress responses or while performing a control task. Salivary cortisol levels were measured to control for the effectiveness of the stress induction. One week later, participants attempted to identify the thief from target-present and target-absent line-ups. According to regression and receiver operating characteristic analyses, stress did not have robust detrimental effects on identification performance. Copyright Š 2016 John Wiley & Sons, Ltd
Residual Human Immunodeficiency Virus (HIV) Type 1 RNA and DNA in Lymph Nodes and HIV RNA in Genital Secretions and in Cerebrospinal Fluid after Suppression of Viremia for 2 Years
Residual viral replication persists in a significant proportion of human immunodeficiency virus (HIV)-infected patients receiving potent antiretroviral therapy. To determine the source of this virus, levels of HIV RNA and DNA from lymphoid tissues and levels of viral RNA in serum, cerebrospinal fluid (CSF), and genital secretions in 28 patients treated for ⊽2.5 years with indinavir, zidovudine, and lamivudine were examined. Both HIV RNA and DNA remained detectable in all lymph nodes. In contrast, HIV RNA was not detected in 20 of 23 genital secretions or in any of 13 CSF samples after 2 years of treatment. HIV envelope sequence data from plasma and lymph nodes from 4 patients demonstrated sequence divergence, which suggests varying degrees of residual viral replication in 3 and absence in 1 patient. In patients receiving potent antiretroviral therapy, the greatest virus burden may continue to be in lymphoid tissues rather than in central nervous system or genitourinary compartment
Isotope fractionation and mixing in methane plumes from the Logatchev hydrothermal field
As methane is consumed in the deep sea, its 13C/12C ratio progressively increases because of kinetic isotope fractionation. Many submarine hydrothermal vents emit methane with carbon isotope ratios that are higher than those of background methane in the surrounding ocean. Since the latter exists at low concentrations, mixing of background methane with vent fluid tends to decrease the 13C/12C ratio as concentration decreases, opposite to the trend produced by consumption. We investigated CH4 concentration and δ13C together with δ3He in plumes from the Logatchev hydrothermal field (LHF) located at 14°45â˛N, 45°W, which generates relatively heavy methane (δ13C â â13â°) by serpentinization of ultramafic rock. The measured methane and δ3He were well correlated at high concentrations, indicating a CH4/3He ratio of 1 Ă 108 in the vent fluids. These tracer distributions were also simulated with an advection-diffusion model in which methane consumption only occurs above a certain threshold concentration. We utilized δ3He to calculate the methane remaining in solution after oxidation, f, and the deviation of δ13C from the value expected from mixing alone, Îδ13C. Both in the model and in the data, the entire set of Îδ13C values are not correlated with log f, which is due to continuous oxidation within the plume while mixing with background seawater. A linear relationship, however, is found in the model for methane at concentrations sufficiently above background, and many of the samples with elevated CH4 north of LHF exhibit a linear trend of Îδ13C versus log f as well. From this trend, the kinetic isotope fractionation factor in the LHF plumes appears to be about 1.015. This value is somewhat higher than found in some other deep-sea studies, but it is lower than found in laboratory incubation experiments
The Influence of Perpetrator Exposure Time and Weapon Presence/Timing on Eyewitness Confidence and Accuracy
Crimes can occur in a matter of seconds, with little time available for an eyewitness to encode a perpetratorâs face. The presence of a weapon can further exacerbate this situation. Few studies have featured mock crimes of short duration, especially with a weapon manipulation. We conducted an experiment to investigate the impact of weapon presence and short perpetrator exposure times (3 versus 10 s) on eyewitness confidence and accuracy. We found that recall concerning the perpetrator was worse when a weapon was present, replicating the weapon focus effect. However, there was no effect on eyewitness identification accuracy. Calibration analyses revealed that all conditions produced a strong confidence-accuracy relationship. Confidence- Accuracy Characteristic curves illustrated almost perfect accuracy for suspect identifications at the highest levels of confidence. We conclude that weapon presence during a brief crime does not necessarily result in negative consequences for either eyewitness identification accuracy or the confidence-accuracy relationship
From nanoliter to large-scale bioreactors: How integrated technologies bring antibody treatments to patients faster
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Receiver operating characteristic analysis of age-related changes in lineup performance
In the basic face memory literature, support has been found for the late maturation hypothesis, which holds that face recognition ability is not fully developed until at least adolescence. Support for the late maturation hypothesis in the criminal lineup identification literature, however, has been equivocal because of the analytic approach that has been used to examine age-related changes in identification performance. Recently, receiver operator characteristic (ROC) analysis was applied for the first time in the adult eyewitness memory literature to examine whether memory sensitivity differs across different types of lineup tests. ROC analysis allows for the separation of memory sensitivity from response bias in the analysis of recognition data. Here, we have made the first ROC-based comparison of adultsâ and childrenâs (5- and 6-year-olds and 9- and 10-year-olds) memory performance on lineups by reanalyzing data from Humphries, Holliday, and Flowe (2012). In line with the late maturation hypothesis, memory sensitivity was significantly greater for adults compared with young children. Memory sensitivity for older children was similar to that for adults. The results indicate that the late maturation hypothesis can be generalized to account for age-related performance differences on an eyewitness memory task. The implications for developmental eyewitness memory research are discussed
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