6,736 research outputs found
Single-filament Composite MgB2/SUS Ribbons by Powder-In-Tube Process
We report the successful fabrication of single-filament composite MgB2/SUS
ribbons, as an ultra-robust conductor type, employing the powder-in-tube (PIT)
process, by swaging and cold rolling only. The remarkable transport critical
current (Ic) of the non-sintered MgB2/SUS ribbon has observed, as an unexpected
result. Transport critical currents Ic ~ 316 A at T = 4.2 K and Ic ~ 82 A at T
= 20 K were observed at self-field, for the non-sintered composite MgB2/SUS
ribbon. In addition, the persistent current density Jp values, that were
estimated by Bean formula, were more than ~ 7  105 A/cm2 at T = 5 K,
and ~ 1.2  105 A/cm2 at T = 30 K, for the sintered composite MgB2/SUS
ribbon, at H = 0 G.Comment: 10 pages, 4 figure
The Dawn of Open Access to Phylogenetic Data
The scientific enterprise depends critically on the preservation of and open
access to published data. This basic tenet applies acutely to phylogenies
(estimates of evolutionary relationships among species). Increasingly,
phylogenies are estimated from increasingly large, genome-scale datasets using
increasingly complex statistical methods that require increasing levels of
expertise and computational investment. Moreover, the resulting phylogenetic
data provide an explicit historical perspective that critically informs
research in a vast and growing number of scientific disciplines. One such use
is the study of changes in rates of lineage diversification (speciation -
extinction) through time. As part of a meta-analysis in this area, we sought to
collect phylogenetic data (comprising nucleotide sequence alignment and tree
files) from 217 studies published in 46 journals over a 13-year period. We
document our attempts to procure those data (from online archives and by direct
request to corresponding authors), and report results of analyses (using
Bayesian logistic regression) to assess the impact of various factors on the
success of our efforts. Overall, complete phylogenetic data for ~60% of these
studies are effectively lost to science. Our study indicates that phylogenetic
data are more likely to be deposited in online archives and/or shared upon
request when: (1) the publishing journal has a strong data-sharing policy; (2)
the publishing journal has a higher impact factor, and; (3) the data are
requested from faculty rather than students. Although the situation appears
dire, our analyses suggest that it is far from hopeless: recent initiatives by
the scientific community -- including policy changes by journals and funding
agencies -- are improving the state of affairs
Bifurcation analysis of delay-induced resonances of the El-Nino Southern Oscillation
Models of global climate phenomena of low to intermediate complexity are very
useful for providing an understanding at a conceptual level. An important
aspect of such models is the presence of a number of feedback loops that
feature considerable delay times, usually due to the time it takes to transport
energy (for example, in the form of hot/cold air or water) around the globe. In
this paper we demonstrate how one can perform a bifurcation analysis of the
behaviour of a periodically-forced system with delay in dependence on key
parameters. As an example we consider the El-Nino Southern Oscillation (ENSO),
which is a sea surface temperature oscillation on a multi-year scale in the
basin of the Pacific Ocean. One can think of ENSO as being generated by an
interplay between two feedback effects, one positive and one negative, which
act only after some delay that is determined by the speed of transport of
sea-surface temperature anomalies across the Pacific. We perform here a case
study of a simple delayed-feedback oscillator model for ENSO (introduced by
Tziperman et al, J. Climate 11 (1998)), which is parametrically forced by
annual variation. More specifically, we use numerical bifurcation analysis
tools to explore directly regions of delay-induced resonances and other
stability boundaries in this delay-differential equation model for ENSO.Comment: as accepted for Proc Roy Soc A, 20 pages, 7 figure
Neutrino-driven Explosions
The question why and how core-collapse supernovae (SNe) explode is one of the
central and most long-standing riddles of stellar astrophysics. A solution is
crucial for deciphering the SN phenomenon, for predicting observable signals
such as light curves and spectra, nucleosynthesis, neutrinos, and gravitational
waves, for defining the role of SNe in the evolution of galaxies, and for
explaining the birth conditions and properties of neutron stars (NSs) and
stellar-mass black holes. Since the formation of such compact remnants releases
over hundred times more energy in neutrinos than the SN in the explosion,
neutrinos can be the decisive agents for powering the SN outburst. According to
the standard paradigm of the neutrino-driven mechanism, the energy transfer by
the intense neutrino flux to the medium behind the stagnating core-bounce
shock, assisted by violent hydrodynamic mass motions (sometimes subsumed by the
term "turbulence"), revives the outward shock motion and thus initiates the SN
blast. Because of the weak coupling of neutrinos in the region of this energy
deposition, detailed, multidimensional hydrodynamic models including neutrino
transport and a wide variety of physics are needed to assess the viability of
the mechanism. Owing to advanced numerical codes and increasing supercomputer
power, considerable progress has been achieved in our understanding of the
physical processes that have to act in concert for the success of
neutrino-driven explosions. First studies begin to reveal observational
implications and avenues to test the theoretical picture by data from
individual SNe and SN remnants but also from population-integrated observables.
While models will be further refined, a real breakthrough is expected through
the next Galactic core-collapse SN, when neutrinos and gravitational waves can
be used to probe the conditions deep inside the dying star. (abridged)Comment: Author version of chapter for 'Handbook of Supernovae,' edited by A.
Alsabti and P. Murdin, Springer. 54 pages, 13 figure
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Uncovering the hidden costs of offshoring: The interplay of complexity, organizational design, and experience
This study investigates estimation errors due to hidden costs—the costs of implementation that are neglected in strategic decision-making processes—in the context of services offshoring. Based on data from the Offshoring Research Network, we find that decision makers are more likely to make cost-estimation errors given increasing configuration and task complexity in captive offshoring and offshore outsourcing, respectively. Moreover, we show that experience and a strong orientation toward organizational design in the offshoring strategy reduce the cost-estimation errors that follow from complexity. Our findings contribute to research on the effectiveness of sourcing and global strategies by stressing the importance of organizational design and experience in dealing with increasing complexity
Regulation of Glomerular Endothelial Cell Proteoglycans by Glucose
The presence of heparan sulfate proteoglycan (HSPG) in anionic sites in the lamina rara interna of glomerular basement membrane suggests that the proteoglycan may be deposited by the glomerular endothelial cells (GEndo). We have previously demonstrated that bovine GEndo in vitro synthesize perlecan, a species of glomerular basement membrane HSPG. In this study we examined whether high glucose medium regulates the GEndo metabolism of glycopeptides including perlecan. Metabolic labeling of glycoconjugates with 35S-SO4, sequential ion exchange and Sepharose CL-4B chromatography of labeled glycoconjugates, and northern analysis were performed. Incubation of GEndo for 8 to 14 weeks (but not for 1-2 weeks) in medium containing 30 mM glucose resulted in nearly 50% reduction in the synthesis of cell layer and medium 35SO4-labeled low anionic glycoproteins and proteoglycans, including that of basement membrane HSPG (Kav 0.42) compared to GEndo grown in 5 mM glucose medium; no changes in anionic charge density or hydrodynamic size of proteoglycans were noted. Northern analysis demonstrated that the mRNA abundance of perlecan was reduced by 47% in cells incubated with 30 mM glucose. Our data suggest that high glucose medium reduces the GEndo synthesis of perlecan by regulating its gene expression. Reduced synthesis of perlecan by GEndo may contribute to proteinuria seen in diabetic nephropathy
Craniopharyngioma in children: trends from a third consecutive single-center cohort study
OBJECTIVE: The management of children with craniopharyngioma has evolved over time, with a trend toward less invasive neurosurgical approaches as surgeons have sought to balance oncological control and treatment-related morbidity. To this end, the aim of this study was to evaluate the safety and effectiveness of the current management of children with craniopharyngioma compared to the previous management methods used at the authors’ treatment center. METHODS: A prospectively maintained database was searched over a 14-year period between January 1, 2005, and December 31, 2018, to identify all children 17 years of age or younger with a new diagnosis of craniopharyngioma. A retrospective case note review was performed for each child to extract data on the presentation, investigation, treatment, and outcome of their illness. Morbidity was assessed in the same fashion as in previous cohorts, according to the following categories: visual loss, pituitary dysfunction, hypothalamic dysfunction, neurological deficits, and cognitive impairment. RESULTS: In total, 59 children were identified with craniopharyngioma during the study period. A total of 92 operations were performed, including cyst drainage (35/92; 38.0%), craniotomy and resection (30/92; 32.6%), and transsphenoidal resection (16/92; 17.4%). Approximately two-thirds of all operations were performed using image guidance (66/92; 71.7%) and one-third were performed using endoscopy (27/92; 29.3%). The majority of children had adjuvant therapy comprising proton beam therapy (18/59; 30.5%) or conventional radiotherapy (16/59; 27.1%). The median follow-up duration was 44 months (range 1–142 months), and approximately one-half of the children had no evidence of residual disease on MRI studies (28/59; 47.5%). Of the remaining 31 children, there was a reduction in the volume of residual disease in 8 patients (8/59; 13.6%), stable residual disease in 18 (18/59; 30.5%), and tumor growth in 5 patients (5/59; 8.5%). There was significantly reduced morbidity (p < 0.05) in all categories in the current cohort compared with our last cohort (1996–2004). CONCLUSIONS: The authors’ institutional experience of pediatric craniopharyngioma confirms a trend toward less invasive neurosurgical procedures, most of which are now performed with the benefit of image guidance or endoscopy. Moreover, the authors have identified an expanding role for more targeted radiotherapy for children with residual disease. These advances have allowed for tumor control comparable to that achieved in previous cohorts, but with significantly reduced morbidity and mortality
Efficacy of heat-killed and formalin-killed vaccines against Tilapia tilapinevirus in juvenile Nile tilapia ( Oreochromis niloticus )
Tilapia tilapinevirus (also known as tilapia lake virus, TiLV) is considered to be a new threat to the global tilapia industry. The objective of this study was to develop simple cell culture‐based heat‐killed (HKV) and formalin‐killed (FKV) vaccines for the prevention of disease caused by TiLV. The fish were immunized with 100 µl of either HKV or FKV by intraperitoneal injection with each vaccine containing 1.8 × 10(6) TCID(50‐)inactivated virus. A booster vaccination was carried out at 21‐day post‐vaccination (dpv) using the same protocol. The fish were then challenged with a lethal dose of TiLV at 28 dpv. The expression of five immune genes (IgM, IgD, IgT, CD4 and CD8) in the head kidney and spleen of experimental fish was assessed at 14 and 21 dpv and again after the booster vaccination at 28 dpv. TiLV‐specific IgM responses were measured by ELISA at the same time points. The results showed that both vaccines conferred significant protection, with relative percentage survival of 71.3% and 79.6% for HKV and FKV, respectively. Significant up‐regulation of IgM and IgT was observed in the head kidney of fish vaccinated with HKV at 21 dpv, while IgM, IgD and CD4 expression increased in the head kidney of fish receiving FKV at the same time point. After booster vaccination, IgT and CD8 transcripts were significantly increased in the spleen of fish vaccinated with the HKV, but not with FKV. Both vaccines induced a specific IgM response in both serum and mucus. In summary, this study showed that both HKV and FKV are promising injectable vaccines for the prevention of disease caused by TiLV in Nile tilapia
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Somato-Dendritic Localization and Signaling by Leptin Receptors in Hypothalamic POMC and AgRP Neurons
Leptin acts via neuronal leptin receptors to control energy balance. Hypothalamic pro-opiomelanocortin (POMC) and agouti-related peptide (AgRP)/Neuropeptide Y (NPY)/GABA neurons produce anorexigenic and orexigenic neuropeptides and neurotransmitters, and express the long signaling form of the leptin receptor (LepRb). Despite progress in the understanding of LepRb signaling and function, the sub-cellular localization of LepRb in target neurons has not been determined, primarily due to lack of sensitive anti-LepRb antibodies. Here we applied light microscopy (LM), confocal-laser scanning microscopy (CLSM), and electron microscopy (EM) to investigate LepRb localization and signaling in mice expressing a HA-tagged LepRb selectively in POMC or AgRP/NPY/GABA neurons. We report that LepRb receptors exhibit a somato-dendritic expression pattern. We further show that LepRb activates STAT3 phosphorylation in neuronal fibers within several hypothalamic and hindbrain nuclei of wild-type mice and rats, and specifically in dendrites of arcuate POMC and AgRP/NPY/GABA neurons of Leprb+/+ mice and in Leprbdb/db mice expressing HA-LepRb in a neuron specific manner. We did not find evidence of LepRb localization or STAT3-signaling in axon-fibers or nerve-terminals of POMC and AgRP/NPY/GABA neurons. Three-dimensional serial EM-reconstruction of dendritic segments from POMC and AgRP/NPY/GABA neurons indicates a high density of shaft synapses. In addition, we found that the leptin activates STAT3 signaling in proximity to synapses on POMC and AgRP/NPY/GABA dendritic shafts. Taken together, these data suggest that the signaling-form of the leptin receptor exhibits a somato-dendritic expression pattern in POMC and AgRP/NPY/GABA neurons. Dendritic LepRb signaling may therefore play an important role in leptin’s central effects on energy balance, possibly through modulation of synaptic activity via post-synaptic mechanisms
Symptoms and signs of lung cancer prior to diagnosis: case-control study using electronic health records from ambulatory care within a large US-based tertiary care centre.
OBJECTIVE: Lung cancer is the most common cause of cancer-related death in the USA. While most patients are diagnosed following symptomatic presentation, no studies have compared symptoms and physical examination signs at or prior to diagnosis from electronic health records (EHRs) in the USA. We aimed to identify symptoms and signs in patients prior to diagnosis in EHR data. DESIGN: Case-control study. SETTING: Ambulatory care clinics at a large tertiary care academic health centre in the USA. PARTICIPANTS, OUTCOMES: We studied 698 primary lung cancer cases in adults diagnosed between 1 January 2012 and 31 December 2019, and 6841 controls matched by age, sex, smoking status and type of clinic. Coded and free-text data from the EHR were extracted from 2 years prior to diagnosis date for cases and index date for controls. Univariate and multivariable conditional logistic regression were used to identify symptoms and signs associated with lung cancer at time of diagnosis, and 1, 3, 6 and 12 months before the diagnosis/index dates. RESULTS: Eleven symptoms and signs recorded during the study period were associated with a significantly higher chance of being a lung cancer case in multivariable analyses. Of these, seven were significantly associated with lung cancer 6 months prior to diagnosis: haemoptysis (OR 3.2, 95% CI 1.9 to 5.3), cough (OR 3.1, 95% CI 2.4 to 4.0), chest crackles or wheeze (OR 3.1, 95% CI 2.3 to 4.1), bone pain (OR 2.7, 95% CI 2.1 to 3.6), back pain (OR 2.5, 95% CI 1.9 to 3.2), weight loss (OR 2.1, 95% CI 1.5 to 2.8) and fatigue (OR 1.6, 95% CI 1.3 to 2.1). CONCLUSIONS: Patients diagnosed with lung cancer appear to have symptoms and signs recorded in the EHR that distinguish them from similar matched patients in ambulatory care, often 6 months or more before diagnosis. These findings suggest opportunities to improve the diagnostic process for lung cancer
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