3,189 research outputs found
Locomotor kinematics of the manus and pes in dinocephalian therapsids reconstructed from three-dimensional morphology of footprints from Gansfontein, South Africa
The Gansfontein paleosurface from the Late PermianAbrahamskraal Formation (Beaufort Group, TapinocephalusAssemblage Zone) near Fraserburg, South Africa, preserves several vertebratetrackways. Among the best-preserved trackways is a series of several footprintsthat have been attributed to a single dinocephalian therapsid walking acrossthe surface. This attribution is based on both the large size of the footprints(25 cm in breadth), and the reduction of digit I in the manus and pes. However,a curious feature of this trackway is that, in contrast to the straight digitsindicated by skeletal specimens of dinocephalians, the digit impressions from theprints are curved so that their tips point medially. To test hypotheses aboutthe locomotor kinematics of the dinocephalian manus and pes that produced thesecurved-digit prints, we constructed contour maps that depicted how the depth ofan impression varied within individual prints. In our initial analysis, we constructedthe maps by pouring milk into the prints in successive increments of 2 mm inheight, and tracing the perimeters of filled areas on translucent paper fixedto the paleosurface by tape. We have also used surface scanners to generatedepth profiles with finer scale resolution. These analyses indicated that thedistal tips of digit impressions are among the shallowest portions of theprints, a pattern consistent with outward rotation of the hand and foot duringstance. In addition, heel impressions are lacking in the prints, indicatingthat the animal that made them may have used digitigrade foot posture. Spacing betweenleft and right prints is small, less than the breadth of individual prints.However, the presence of foot rotation during stance suggests thatdinocephalians used sprawling, rather than parasagittal limb posture. Closespacing of footprints likely resulted from a combination of lateral bending ofthe body and significant cranio-caudal limb excursion, rather than increasedadduction of the limbs under the body.Fil: Blob, Richard W.. Clemson University; Estados UnidosFil: Wilson, Jeffrey A.. University of Michigan; Estados UnidosFil: Marsicano, Claudia Alicia. Consejo Nacional de Investigaciones CientÃficas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Estudios Andinos "Don Pablo Groeber". Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Estudios Andinos "Don Pablo Groeber"; ArgentinaFil: Panko, Laura J.. Northwestern University; Estados UnidosFil: Smith, Roger M.. Iziko South African Museum Cape Town; Sudáfrica77th Annual Meeting of the Society of Vertebrate PaleontologyCanadáSociety of Vertebrate Paleontolog
Increased Blood Pressure Variability Is Associated with Worse Neurologic Outcome in Acute Anterior Circulation Ischemic Stroke
Background. Although research suggests that blood pressure variability (BPV) is detrimental in the weeks to months after acute ischemic stroke, it has not been adequately studied in the acute setting. Methods. We reviewed acute ischemic stroke patients from 2007 to 2014 with anterior circulation stroke. Mean blood pressure and three BPV indices (standard deviation, coefficient of variation, and successive variation) for the intervals 0–24, 0–72, and 0–120 hours after admission were correlated with follow-up modified Rankin Scale (mRS) in ordinal logistic regression models. The correlation between BPV and mRS was further analyzed by terciles of clinically informative stratifications. Results. Two hundred and fifteen patients met inclusion criteria. At all time intervals, increased systolic BPV was associated with higher mRS, but the relationship was not significant for diastolic BPV or mean blood pressure. This association was strongest in patients with proximal stroke parent artery vessel occlusion and lower mean blood pressure. Conclusion. Increased early systolic BPV is associated with worse neurologic outcome after ischemic stroke. This association is strongest in patients with lower mean blood pressure and proximal vessel occlusion, often despite endovascular or thrombolytic therapy. This hypothesis-generating dataset suggests potential benefit for interventions aimed at reducing BPV in this patient population
High Density Circumstellar Interaction in the Luminous Type IIn SN 2010jl: The first 1100 days
HST and ground based observations of the Type IIn SN 2010jl are analyzed,
including photometry, spectroscopy in the ultraviolet, optical and NIR bands,
26-1128 days after first detection. At maximum the bolometric luminosity was
erg/s and even at 850 days exceeds erg/s. A NIR
excess, dominating after 400 days, probably originates in dust in the
circumstellar medium (CSM). The total radiated energy is
ergs, excluding the dust component. The spectral lines can be separated into
one broad component due to electron scattering, and one narrow with expansion
velocity km/s from the CSM. The broad component is initially
symmetric around zero velocity but becomes blueshifted after days,
while remaining symmetric about a shifted centroid velocity. Dust absorption in
the ejecta is unlikely to explain the line shifts, and we attribute the shift
instead to acceleration by the SN radiation. From the optical lines and the
X-ray and dust properties, there is strong evidence for large scale asymmetries
in the CSM. The ultraviolet lines indicate CNO processing in the progenitor,
while the optical shows a number of narrow coronal lines excited by the X-rays.
The bolometric light curve is consistent with a radiative shock in an
CSM with a mass loss rate of M_sun/yr. The total mass lost is
M_sun. These properties are consistent with the SN expanding into a CSM
characteristic of an LBV progenitor with a bipolar geometry. The apparent
absence of nuclear processing is attributed to a CSM still opaque to electron
scattering.Comment: ApJ in press. Updated and changed after referees comment
Maternal exposure to childhood traumatic events, but not multi-domain psychosocial stressors, predict placental corticotrophin releasing hormone across pregnancy
Maternal psychosocial stress increases the risk of adverse birth and postnatal outcomes for the mother and child, but the role of maternal exposure to childhood traumatic events (CTE) and multi-domain psychosocial stressors for the level and rise of placental Corticotrophin-Releasing Hormone (pCRH) across pregnancy has been understudied. In a sociodemographically and racially diverse sample of 1303 women (64% Black, 36% White/others) with low-medical risk pregnancies at enrollment from Shelby County, Tennessee, USA, blood samples were drawn twice, corresponding roughly to second and third trimester, and extracted prior to conducting radioimmune assays for pCRH. Mothers reported CTE (physical abuse, sexual abuse, or family violence, in childhood), adulthood traumatic events, and interpersonal violence during pregnancy. Neighborhood crime/deprivation was derived using geospatially-linked objective databases. General linear and mixed models tested associations between stress exposure variables and pCRH levels and rate of rise, adjusting for obstetric/clinical/health related factors. Maternal CTE did not predict pCRH levels at time 1, but positively predicted levels at time 2, and the rate of rise in pCRH across pregnancy. Race did not moderate this association. No additional maternal stress exposures across adulthood or during pregnancy predicted pCRH outcomes. Findings indicate that childhood violence or abuse exposure can become biologically embedded in a manner predicting later prenatal physiology relevant for maternal and offspring health, and that such embedding may be specific to childhood, but not adulthood, stress. Findings also highlight the placental-fetal unit as a mechanistic pathway through which intergenerational transmission of the adverse effects of childhood adversities may occur.publishedVersio
Caltech Core-Collapse Project (CCCP) observations of type IIn supernovae: typical properties and implications for their progenitor stars
Type IIn Supernovae (SNe IIn) are rare events, constituting only a few
percent of all core-collapse SNe, and the current sample of well observed SNe
IIn is small. Here, we study the four SNe IIn observed by the Caltech
Core-Collapse Project (CCCP). The CCCP SN sample is unbiased to the extent that
object selection was not influenced by target SN properties. Therefore, these
events are representative of the observed population of SNe IIn. We find that a
narrow P-Cygni profile in the hydrogen Balmer lines appears to be a ubiquitous
feature of SNe IIn. Our light curves show a relatively long rise time (>20
days) followed by a slow decline stage (0.01 to 0.15 mag/day), and a typical
V-band peak magnitude of M_V=-18.4 +/- 1.0 mag. We measure the progenitor star
wind velocities (600 - 1400 km/s) for the SNe in our sample and derive
pre-explosion mass loss rates (0.026 - 0.12 solar masses per year). We compile
similar data for SNe IIn from the literature, and discuss our results in the
context of this larger sample. Our results indicate that typical SNe IIn arise
from progenitor stars that undergo LBV-like mass-loss shortly before they
explode.Comment: ApJ, submitte
Dynamic Patterns of Threat-Associated Gene Expression in the Amygdala and Blood
Stress and trauma profoundly influence psychiatric biobehavioral outcomes. The identification of treatment and biomarker targets would be accelerated by a broad understanding of the biological responses to these events. The goal of this study was to determine genes responsive to auditory fear conditioning (FC), a well-characterized amygdala-dependent rodent model of threat-exposure, in the presence or absence of prior stress history, providing insight into the physiological processes underlying response to trauma. RNA-sequencing was performed in blood and amygdala from mice that underwent fear conditioning with (Immo+FC) and without (FC) prior immobilization stress, a paradigm that induces HPA axis, and behavioral stress sensitization. In the amygdala, 607 genes were regulated by FC vs. home-cage (HC) controls, and 516 genes differed in stress-sensitized mice (Immo+FC vs. FC). In the former, we observed an enhancement of specific biological processes involved in learning and synaptic transmission, and in the latter processes associated with cell proliferation and the cellular response to drugs. In the blood of stress-sensitized animals, 468 genes were dynamically regulated when compared to FC, and were enriched for the biological pathways of inflammation and cytokine signaling. This study identified genes and pathways that respond to threat in the amygdala and blood of mice with and without a prior stress history and reveals the impact of stress history on subsequent inflammation. Future studies will be needed to examine the role of these dynamically regulated genes may play in human clinical stress and trauma-related disorders
Right ventricular volumes and function in thalassemia major patients in the absence of myocardial iron overload
<p>Abstract</p> <p>Aim</p> <p>We aimed to define reference ranges for right ventricular (RV) volumes, ejection fraction (EF) in thalassemia major patients (TM) without myocardial iron overload.</p> <p>Methods and results</p> <p>RV volumes, EF and mass were measured in 80 TM patients who had no myocardial iron overload (myocardial T2* > 20 ms by cardiovascular magnetic resonance). All patients were receiving deferoxamine chelation and none had evidence of pulmonary hypertension or other cardiovascular comorbidity. Forty age and sex matched healthy non-anemic volunteers acted as controls. The mean RV EF was higher in TM patients than controls (males 66.2 ± 4.1% vs 61.6 ± 6%, p = 0.0009; females 66.3 ± 5.1% vs 62.6 ± 6.4%, p = 0.017), which yielded a raised lower threshold of normality for RV EF in TM patients (males 58.0% vs 50.0% and females 56.4% vs 50.1%). RV end-diastolic volume index was higher in male TM patients (mean 98.1 ± 17.3 mL vs 88.4 ± 11.2 mL/m2, p = 0.027), with a higher upper limit (132 vs 110 mL/m2) but this difference was of borderline significance for females (mean 86.5 ± 13.6 mL vs 80.3 ± 12.8 mL/m2, p = 0.09, with upper limit of 113 vs 105 mL/m2). The cardiac index was raised in TM patients (males 4.8 ± 1.0 L/min vs 3.4 ± 0.7 L/min, p < 0.0001; females 4.5 ± 0.8 L/min vs 3.2 ± 0.8 L/min, p < 0.0001). No differences in RV mass index were identified.</p> <p>Conclusion</p> <p>The normal ranges for functional RV parameters in TM patients with no evidence of myocardial iron overload differ from healthy non-anemic controls. The new reference RV ranges are important for determining the functional effects of myocardial iron overload in TM patients.</p
Type IIb Supernova SN 2011dh: Spectra and Photometry from the Ultraviolet to the Near-Infrared
We report spectroscopic and photometric observations of the Type IIb SN
2011dh obtained between 4 and 34 days after the estimated date of explosion
(May 31.5 UT). The data cover a wide wavelength range from 2,000 Angstroms in
the UV to 2.4 microns in the NIR. Optical spectra provide line profiles and
velocity measurements of HI, HeI, CaII and FeII that trace the composition and
kinematics of the SN. NIR spectra show that helium is present in the atmosphere
as early as 11 days after the explosion. A UV spectrum obtained with the STIS
reveals that the UV flux for SN 2011dh is low compared to other SN IIb. The HI
and HeI velocities in SN 2011dh are separated by about 4,000 km/s at all
phases. We estimate that the H-shell of SN 2011dh is about 8 times less massive
than the shell of SN 1993J and about 3 times more massive than the shell of SN
2008ax. Light curves (LC) for twelve passbands are presented. The maximum
bolometric luminosity of erg s occurred
about 22 days after the explosion. NIR emission provides more than 30% of the
total bolometric flux at the beginning of our observations and increases to
nearly 50% of the total by day 34. The UV produces 16% of the total flux on day
4, 5% on day 9 and 1% on day 34. We compare the bolometric light curves of SN
2011dh, SN 2008ax and SN 1993J. The LC are very different for the first twelve
days after the explosions but all three SN IIb display similar peak
luminosities, times of peak, decline rates and colors after maximum. This
suggests that the progenitors of these SN IIb may have had similar compositions
and masses but they exploded inside hydrogen shells that that have a wide range
of masses. The detailed observations presented here will help evaluate
theoretical models for this supernova and lead to a better understanding of SN
IIb.Comment: 23 pages, 14 figures, 9 tables, accepted by Ap
- …