2,838 research outputs found
Measuring and preliminary modeling of drift interception by plant species
Currently, the concept of plant capture efficiency is not quantitatively considered in the evaluation of off-target drift for the purposes of pesticide risk assessment in the United States. For on-target pesticide applications, canopy capture efficiency is managed by optimizing formulations or tank-mixing with adjuvants to maximize retention of spray droplets. These efforts take into consideration the fact that plant species have diverse morphology and surface characteristics, and as such will retain varying levels of applied pesticides. This work aims to combine plant surface wettability potential, spray droplet characteristics, and plant morphology into describing the plant capture efficiency of drifted spray droplets. In this study, we used wind tunnel experiments and individual plants grown to 10–20 cm to show that at two downwind distances and with two distinct nozzles capture efficiency for sunflower (Helianthus annuus L.), lettuce (Lactuca sativa L.), and tomato (Solanum lycopersicum L.) is consistently higher than rice (Oryza sativa L.), peas (Pisum sativum L). and onions (Allium cepa L.), with carrots (Daucus carota L.) showing high variability and falling between the two groups. We also present a novel method for three-dimensional modeling of plants from photogrammetric scanning and use the results in the first known computational fluid dynamics simulations of drift capture efficiency on plants. The mean simulated drift capture efficiency rates were within the same order of magnitude of the mean observed rates of sunflower and lettuce, and differed by one to two orders for rice and onion. We identify simulating the effects of surface roughness on droplet behavior, and the effects of wind flow on plant movement as potential model improvements requiring further species-specific data collection
Certificates of Confidentiality: Protecting Human Subject Research Data in Law and Practice
The federal Certificate of Confidentiality plays an important role in research on sensitive topics by authorizing researchers to refuse to disclose identifiable research data in response to subpoenas in any legal setting. However, there is little known about how effective Certificates are in practice. This article draws on our legal and empirical research on this topic to fill this information gap. It includes a description of the purpose of Certificates, their legislative and regulatory history, and a summary of the few reported and unreported cases that have dealt with Certificates. In addition, we outline other statutory confidentiality protections, compare them to the Certificate\u27s protections, and analyze some of the vulnerabilities of a Certificate\u27s protections. This analysis allows us to make specific recommendations for strengthening the protections afforded to research data
Clocking the onset of bilayer coherence in a high- cuprate
In cuprates, a precursor state of superconductivity is speculated to exist above the critical temperature TC. Here we show via a combination of far-infrared ellipsometry and ultrafast broadband optical spectroscopy that signatures of such a state can be obtained via three independent observables in an underdoped sample of NdBa2Cu3O6+δ. The pseudogap correlations were disentangled from the response of laser-broken pairs by clocking their characteristic time scales. The onset of a superconducting precursor state was found at a temperature TONS>TC, consistent with the temperature scale identified via static optical spectroscopy. Furthermore, the temperature evolution of the coherent vibration of the Ba ion, strongly renormalized by the onset of superconductivity, revealed a pronounced anomaly at the same temperature TONS. The microscopic nature of such a precursor state is discussed in terms of preformed pairs and enhanced bilayer coherence
Deep generative modeling for single-cell transcriptomics.
Single-cell transcriptome measurements can reveal unexplored biological diversity, but they suffer from technical noise and bias that must be modeled to account for the resulting uncertainty in downstream analyses. Here we introduce single-cell variational inference (scVI), a ready-to-use scalable framework for the probabilistic representation and analysis of gene expression in single cells ( https://github.com/YosefLab/scVI ). scVI uses stochastic optimization and deep neural networks to aggregate information across similar cells and genes and to approximate the distributions that underlie observed expression values, while accounting for batch effects and limited sensitivity. We used scVI for a range of fundamental analysis tasks including batch correction, visualization, clustering, and differential expression, and achieved high accuracy for each task
Susceptibility to tuberculosis is associated with variants in the ASAP1 gene encoding a regulator of dendritic cell migration
Human genetic factors predispose to tuberculosis (TB). We studied 7.6 million genetic variants in 5,530 people with pulmonary TB and in 5,607 healthy controls. In the combined analysis of these subjects and the follow-up cohort (15,087 TB patients and controls altogether), we found an association between TB and variants located in introns of the ASAP1 gene on chromosome 8q24 (P = 2.6 × 10−11 for rs4733781; P = 1.0 × 10−10 for rs10956514). Dendritic cells (DCs) showed high ASAP1 expression that was reduced after Mycobacterium tuberculosis infection, and rs10956514 was associated with the level of reduction of ASAP1 expression. The ASAP1 protein is involved in actin and membrane remodeling and has been associated with podosomes. The ASAP1-depleted DCs showed impaired matrix degradation and migration. Therefore, genetically determined excessive reduction of ASAP1 expression in M. tuberculosis–infected DCs may lead to their impaired migration, suggesting a potential mechanism of predisposition to TB
Inflammation and glucose intolerance. A prospective study of gestational diabetes mellitus
WSTĘP. Podwyższony poziom leukocytów w surowicy krwi jest wskaźnikiem procesu
zapalenia, który, jak wykazują badania prospektywne, wiąże się z rozwojem cukrzycy
typu 2. Chociaż cukrzyca ciążowa oraz cukrzyca typu 2 mają dużo wspólnych mechanizmów
patofizjologicznych, w niewielu pracach badano związek zapalenia z rozwojem cukrzycy
ciążowej.
MATERIAŁ I METODY. W badaniu oceniano w sposób prospektywny liczbę leukocytów w próbkach krwi pobranych podczas pierwszej rutynowej wizyty kontrolnej w grupie
2753 kobiet w ciąży — wieloródek z prawidłową wartością glikemii. U 98 (3,6%)
z nich wystąpiła później cukrzyca ciążowa. Pacjentki podzielono na podgrupy w
zależności od kwartyla liczby leukocytów i porównano wyniki przeprowadzanego w
trzecim trymestrze przesiewowego testu tolerancji glukozy oraz częstość cukrzycy
ciążowej wśród kobiet należących do poszczególnych kwartyli. Zastosowano test
regresji logistycznej, aby obliczyć skorygowane względem jednego i wielu czynników
względne ryzyko wystąpienia cukrzycy ciążowej w zależności od kwartyla leukocytozy.
WYNIKI. U kobiet, u których doszło do rozwoju cukrzycy ciążowej, stężenie
leukocytów w surowicy krwi było wyższe (10,5 ± 2,2 vs. 9,2 ± 2,2 × 103 komórek/ml;
p < 0,01) niż u pacjentek, u których metabolizm węglowodanów pozostał prawidłowy.
Wraz ze wzrostem kwartyla leukocytozy obserwowano liniowy wzrost glikemii po obciążeniu
glukozą (p < 0,01), pola pod krzywą testu tolerancji glukozy (p < 0,01) oraz częstości
cukrzycy ciążowej (kwartyl 1. — 1,1%; kwartyl 2. — 2,5%; kwartyl 3. — 4,2% i kwartyl
4. — 6,4%; p < 0,01). W analizie wieloczynnikowej, wraz ze wzrostem kwartyla leukocytozy,
liniowy trend względnego ryzyka (RR, relative risk) rozwoju cukrzycy ciążowej
pozostał statystycznie istotny [kwartyl 1. — referencyjny, kwartyl 2. — RR 2,3
(95% CI 0,9-5,7), kwartyl 3. — RR 3,3 (1,4–7,8), kwartyl 4. — RR 4,9 (2,1–11,2);
p < 0,01].
WNIOSKI. Podwyższony poziom leukocytów we wczesnym okresie ciąży jest w
sposób niezależny, liniowy związany z wynikami testów przesiewowych w kierunku
cukrzycy ciążowej oraz ryzykiem wystąpienia tej choroby. Brak wyraźnej granicy
w rozkładzie liczby leukocytów sprawia, że wskaźnik ten nie może mieć zastosowania
klinicznego, chociaż dane sugerują, że proces zapalenia wiąże się z rozwojem cukrzycy
ciążowej. Może to być kolejny mechanizm patofizjologiczny, łączący występowanie
cukrzycy ciążowej z rozwojem w przyszłości cukrzycy typu 2.INTRODUCTION. Increased leukocyte count is a marker
of inflammation that has been associated with
the development of type 2 diabetes in prospective
studies. Although gestational diabetes mellitus
(GDM) and type 2 diabetes share certain pathophysiological
mechanisms, few studies have examined
inflammation and risk of GDM.
MATERIAL AND METHODS. We prospectively examined
routine leukocyte counts collected at the first
prenatal visit in a cohort of 2,753 nulliparous euglycemic
women, 98 (3.6%) of whom were later diagnosed
with GDM. Subjects were divided into quartiles
of leukocyte count, and the results of third-trimester
glucose screening tests and the incidence of
GDM among these quartiles were compared. Logistic
regression was used to calculate univariate and
multivariable-adjusted relative risks (RRs) of GDM
according to leukocyte quartiles.
RESULTS. Leukocyte counts were increased among
women who subsequently developed GDM compared
with those who remained free of GDM (10.5 ±
± 2.2 vs. 9.2 ± 2.2 × 103 cells/ml; P < 0.01). There
was a linear increase in postloading mean glucose
levels (P for trend < 0.01), the area under the glucose
tolerance test curves (P for trend < 0.01), and the
incidence of GDM (quartile 1, 1.1; quartile 2, 2.5;
quartile 3, 4.2; and quartile 4, 6.4%; P for trend
< 0.01) with increasing leukocyte quartiles. In the
multivariable-adjusted analysis, the linear trend in
the RR of GDM with increasing leukocyte quartiles
remained statistically significant (quartile 1, reference;
quartile 2, RR 2.3 [95% CI 0.9–5.7]; quartile 3, 3.3
[1.4–7.8]; quartile 4, 4.9 [2.1–11.2]; P for trend < 0.01).
CONCLUSIONS. Increased leukocyte count early in
pregnancy is independently and linearly associated
with the results of GDM screening tests and the risk
of GDM. Although overlap in the leukocyte count
distributions precludes it from being a clinically useful
biomarker, these data suggest that inflammation
is associated with the development of GDM and
may be another pathophysiological link between
GDM and future type 2 diabetes
Perspectives on Astrophysics Based on Atomic, Molecular, and Optical (AMO) Techniques
About two generations ago, a large part of AMO science was dominated by
experimental high energy collision studies and perturbative theoretical
methods. Since then, AMO science has undergone a transition and is now
dominated by quantum, ultracold, and ultrafast studies. But in the process, the
field has passed over the complexity that lies between these two extremes. Most
of the Universe resides in this intermediate region. We put forward that the
next frontier for AMO science is to explore the AMO complexity that describes
most of the Cosmos.Comment: White paper submission to the Decadal Assessment and Outlook Report
on Atomic, Molecular, and Optical (AMO) Science (AMO 2020
Pharmacokinetic, neurochemical, stereological and neuropathological studies on the potential effects of paraquat in the substantia nigra pars compacta and striatum of male C57BL/6J mice
AbstractThe pharmacokinetics and neurotoxicity of paraquat dichloride (PQ) were assessed following once weekly administration to C57BL/6J male mice by intraperitoneal injection for 1, 2 or 3 weeks at doses of 10, 15 or 25mg/kg/week. Approximately 0.3% of the administered dose was taken up by the brain and was slowly eliminated, with a half-life of approximately 3 weeks. PQ did not alter the concentration of dopamine (DA), homovanillic acid (HVA) or 3,4-dihydroxyphenylacetic acid (DOPAC), or increase dopamine turnover in the striatum. There was inconsistent stereological evidence of a loss of DA neurons, as identified by chromogenic or fluorescent-tagged antibodies to tyrosine hydroxylase in the substantia nigra pars compacta (SNpc). There was no evidence that PQ induced neuronal degeneration in the SNpc or degenerating neuronal processes in the striatum, as indicated by the absence of uptake of silver stain or reduced immunolabeling of tyrosine-hydroxylase-positive (TH+) neurons. There was no evidence of apoptotic cell death, which was evaluated using TUNEL or caspase 3 assays. Microglia (IBA-1 immunoreactivity) and astrocytes (GFAP immunoreactivity) were not activated in PQ-treated mice 4, 8, 16, 24, 48, 96 or 168h after 1, 2 or 3 doses of PQ.In contrast, mice dosed with the positive control substance, 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP; 10mg/kg/dose×4 doses, 2h apart), displayed significantly reduced DA and DOPAC concentrations and increased DA turnover in the striatum 7 days after dosing. The number of TH+ neurons in the SNpc was reduced, and there were increased numbers of degenerating neurons and neuronal processes in the SNpc and striatum. MPTP-mediated cell death was not attributed to apoptosis. MPTP activated microglia and astrocytes within 4h of the last dose, reaching a peak within 48h. The microglial response ended by 96h in the SNpc, but the astrocytic response continued through 168h in the striatum.These results bring into question previous published stereological studies that report loss of TH+ neurons in the SNpc of PQ-treated mice. This study also suggests that even if the reduction in TH+ neurons reported by others occurs in PQ-treated mice, this apparent phenotypic change is unaccompanied by neuronal cell death or by modification of dopamine levels in the striatum
Explosion dynamics of pyroclastic eruptions at Santiaguito Volcano
In Jan. 2003 we monitored explosions at Santiaguito Volcano (Guatemala) with thermal, infrasonic, and seismic sensors. Thermal data from 2 infrared thermometers allowed computation of plume rise speeds, which ranged from 8 to 20 m/s. Rise rates correlated with cumulative thermal radiance, indicating that faster rising plumes correspond to explosions with greater thermal flux. The relationship between rise speeds and elastic energy is less clear. Seismic radiation may not scale well with thermal output and/or rise speed because some of the thermal component may be associated with passive degassing, which does not induce significant seismicity. But non-impulsive gas release is still able to produce a high thermal flux, which is the primary control on buoyant rise speed
Validity of the Clock Drawing Test in predicting reports of driving problems in the elderly
BACKGROUND: This study examined the use of the Folstein Mini Mental Status Exam (MMSE) and the Clock Drawing Test (CDT) in predicting retrospective reports of driving problems among the elderly. The utility of existing scoring systems for the CDT was also examined. METHODS: Archival chart records of 325 patients of a geriatric outpatient clinic were reviewed, of which 162 had CDT results (including original clock drawings). T-test, correlation, and regression procedures were used to analyze the data. RESULTS: Both CDT and MMSE scores were significantly worse among non-drivers than individuals who were currently or recently driving. Among current or recent drivers, scores on both instruments correlated significantly with the total number of reported accidents or near misses, although the magnitude of the respective correlations was small. Only MMSE scores, however, significantly predicted whether or not any accidents or near misses were reported at all. Neither MMSE nor CDT scores predicted unique variance in the regressions. CONCLUSIONS: The overall results suggest that both the MMSE and CDT have limited utility as potential indicators of driving problems in the elderly. The demonstrated predictive power for these instruments appears to be redundant, such that both appear to assess general cognitive function versus more specific abilities. Furthermore, the lack of robust prediction suggests that neither are sufficient to serve as stand-alone instruments on which to solely base decisions of driving capacity. Rather, individuals who evidence impairment should be provided a more thorough and comprehensive assessment than can be obtained through screening tools
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