3,913 research outputs found
Multipole (E1, M1, E2, M2, E3, M3) transition wavelengths and rates between 3l5l' excited and ground states in nickel-like ions
A relativistic many-body method is developed to calculate energy and
transition rates for multipole transitions in many-electron ions. This method
is based on relativistic many-body perturbation theory (RMBPT), agrees with
MCDF calculations in lowest-order, includes all second-order correlation
corrections and includes corrections from negative energy states. Reduced
matrix elements, oscillator strengths, and transition rates are calculated for
electric-multipole (dipole (E1), quadrupole (E2), and octupole (E3)) and
magnetic-multipole (dipole (M1), quadrupole (M2), and octupole (M3))
transitions between 3l5l' excited and ground states in Ni-like ions with
nuclear charges ranging from Z = 30 to 100. The calculations start from a
1s22s22p63s23p63d10} Dirac-Fock potential. First-order perturbation theory is
used to obtain intermediate-coupling coefficients, and second-order RMBPT is
used to determine the matrix elements. A detailed discussion of the various
contributions to the dipole matrix elements and energy levels is given for
nickellike tungsten (Z = 74). The contributions from negative-energy states are
included in the second-order E1, M1, E2 M2, E3, and M3 matrix elements. The
resulting transition energies and transition rates are compared with
experimental values and with results from other recent calculations. These
atomic data are important in modeling of M-shell radiation spectra of heavy
ions generated in electron beam ion trap experiments and in M-shell diagnostics
of plasmas.Comment: 21 pages, 8 figures, 11 table
Is socioeconomic status associated with biological aging as measured by telomere length?
It has been hypothesized that one way in which lower socioeconomic status (SES) affects health is by increasing the rate of biological aging. A widely used marker of biological aging is telomere length. Telomeres are structures at the ends of chromosomes that erode with increasing cell proliferation and genetic damage. We aimed to identify, through systematic review and meta-analysis, whether lower SES (greater deprivation) is associated with shorter telomeres. Thirty-one articles, including 29 study populations, were identified. We conducted 3 meta-analyses to compare the telomere lengths of persons of high and low SES with regard to contemporaneous SES (12 study populations from 10 individual articles), education (15 study populations from 14 articles), and childhood SES (2 study populations from 2 articles). For education, there was a significant difference in telomere length between persons of high and low SES in a random-effects model (standardized mean difference (SMD) = 0.060, 95% confidence interval (CI): 0.002, 0.118; P = 0.042), although a range of sensitivity analyses weakened this association. There was no evidence for an association between telomere length and contemporaneous SES (SMD = 0.104, 95% CI: −0.027, 0.236; P = 0.119) or childhood SES (SMD = −0.037, 95% CI: −0.143, 0.069; P = 0.491). These results suggest weak evidence for an association between SES (as measured by education) and biological aging (as measured by telomere length), although there was a lack of consistent findings across the SES measures investigated here
Apple, condom, and cocaine - Body stuffing in prison: A case report
© 2018 The Author(s). Background: Drug dealers and drug users resort to body stuffing to hastily conceal illicit drugs by ingesting their drug packets. This practice represents a medical challenge because rupture of the often insecure packaging can be toxic and even lethal. In an emergency setting, official guidelines are needed to help the medical team decide on the proper treatment. A preliminary observation period is generally accepted but its duration varies from hours to eventual packet expulsion. Case presentation: This case involves a 20-year-old white man in detention who claimed to have ingested one cocaine packet wrapped in plastic food-wrap and a condom in anticipation of an impending cell search. He reached out to medical professionals on day 4 after having unsuccessfully tried several methods to expel the drug packet, including swallowing olive oil, natural laxatives, liters of water, and 12 carved apple chunks. An initial computed tomography scan confirmed multiple packet-sized images throughout his stomach and bowel. After 24 hours of observation and normal bowel movements without expelling any packets, a subsequent scan found only one air-lined packet afloat in the gastric content. Due to the prolonged retention of the package there was an increased risk of rupture. The packet was eventually removed by laparoscopic gastrotomy. Conclusions: This case report illustrates that observation time needs to be adapted to each individual case of body stuffing. Proof of complete drug package evacuation ensures secure patient discharge. Body stuffers should be routinely asked for a detailed history, including how the drug is wrapped, and whether or not they ingested other substances to help expel the packets. The history enables the accurate interpretation of imaging. Repeated imaging can help follow the progress of packets if not all have been expelled during the observation period. Drug packets should be surgically removed in case of prolonged retention. To ensure the best possible outcomes, patients should have access to high-quality, private, and confidential medical care, which is equal to that offered to the general population. This is paramount to earning trust and collaboration from people in detention who resort to body stuffing
Geometrical Insights for Implicit Generative Modeling
Learning algorithms for implicit generative models can optimize a variety of
criteria that measure how the data distribution differs from the implicit model
distribution, including the Wasserstein distance, the Energy distance, and the
Maximum Mean Discrepancy criterion. A careful look at the geometries induced by
these distances on the space of probability measures reveals interesting
differences. In particular, we can establish surprising approximate global
convergence guarantees for the -Wasserstein distance,even when the
parametric generator has a nonconvex parametrization.Comment: this version fixes a typo in a definitio
Intravascular Lymphoma Mimicking Cerebral Stroke: Report of Two Cases
Ischemic stroke is a serious disease leading to significant morbidity and mortality. Multifocal and recurrent strokes are usually caused by embolic diseases, i.e. atrial fibrillation, but rare causes like cerebral vasculitis and clotting disorders are also well known. Here we report on two patients suffering from the very rare intravascular large B-cell lymphoma leading to multifocal and recurrent strokes in the brain and spinal cord as the prominent neurological symptom. The difficulties and the need for diagnostic brain biopsy in making an ‘in vivo’ diagnosis in this particular disease are outlined. Furthermore, the prerequisite for an interdisciplinary approach in these patients is strongly emphasized. Delayed diagnosis for several reasons was the most probable cause for cerebral relapse leading to death in one patient a few months after diagnosis. Conversely, early initiation of immunochemotherapy with a classical lymphoma schedule (R-CHOP) led to long-lasting remission of the disease in the other patient. With this report we like to improve alertness to intravascular large B-cell lymphoma as a cause for multifocal and recurrent strokes
Noisy random Boolean formulae:a statistical physics perspective
Properties of computing Boolean circuits composed of noisy logical gates are studied using the statistical physics methodology. A formula-growth model that gives rise to random Boolean functions is mapped onto a spin system, which facilitates the study of their typical behavior in the presence of noise. Bounds on their performance, derived in the information theory literature for specific gates, are straightforwardly retrieved, generalized and identified as the corresponding macroscopic phase transitions. The framework is employed for deriving results on error-rates at various function-depths and function sensitivity, and their dependence on the gate-type and noise model used. These are difficult to obtain via the traditional methods used in this field
Emerging tick-borne pathogens in the Nordic countries:A clinical and laboratory follow-up study of high-risk tick-bitten individuals
Despite the presence of several microorganisms, other than Borrelia burgdorferi sensu lato (Bbsl) and TBE virus, in Ixodes ricinus ticks from the Nordic countries, data is lacking on their pathogenic potential in humans. In this study, we wanted to investigate the aetiology and clinical manifestations of tick-transmitted infections in individuals seeking medical care following a tick-bite. The sampling frame was participants of a large-scale, prospective, multi-centre, follow-up study of tick-bitten volunteers recruited in Sweden, Finland and Norway in the years 2007-2015. Participants who sought medical care during the three-month follow-up period and from whom blood samples were collected during this healthcare visit (n=92) were tested, using PCR, for exposure to spotted fever group (SFG) Rickettsia spp., Anaplasma phagocytophilum and Babesia spp. Moreover, 86 of these individuals had two serum samples, collected three months apart, tested serologically for six tick-borne microorganisms. The selected organisms-Bbsl, SFG rickettsiae, Anaplasma phagocytophilum, TBE virus, Babesia microti and Bartonella henselae-have all been detected in field-collected ticks from the Nordic countries. Medical records were reviewed and questionnaires were completed to determine clinical manifestations. We found Lyme borreliosis to be the most common tick-transmitted infection as seen in 46 (54%) of the 86 participants with available medical records. Among the 86 participants with paired sera, serological or molecular evidence of recent exposure to other microorganisms than Bbsl could be demonstrated in eight (9%). Five participants (6%) exhibited serological evidence of recent concomitant exposure to more than one tick-borne microorganism. Clinical presentations were mild with one exception (TBE). In conclusion, our data suggest a low risk of infection with tick-borne microorganisms, other than Bbsl, in immunocompetent tick-bitten persons from the examined regions, a low occurrence of co-infection and mostly mild or no overt clinical signs of infection in immunocompetent persons exposed to the studied agents.Funding Agencies|EUEuropean Union (EU) [20200422]; Swedish Research Council Branch of MedicineSwedish Research Council [K2008-58X-14631-06-3]; Medical Research Council of Southeast Sweden; County Council of Ostergotland [LIO-56191]; Independent Research Fund Denmark [8020-00344B]; Wilhelm and Else Stockmann Foundation; Foundation for Aland Medical Research of the Aland Culture Foundation</p
Temperature variations at diffuse and focused flow hydrothermal vent sites along the northern East Pacific Rise
Author Posting. © American Geophysical Union, 2006. This article is posted here by permission of American Geophysical Union for personal use, not for redistribution. The definitive version was published in Geochemistry Geophysics Geosystems 7 (2006): Q03002, doi:10.1029/2005GC001094.In the decade following documented volcanic activity on the East Pacific Rise near 9°50′N, we monitored hydrothermal vent fluid temperature variations in conjunction with approximately yearly vent fluid sampling to better understand the processes and physical conditions that govern the evolution of seafloor hydrothermal systems. The temperature of both diffuse flow (low-temperature) and focused flow (high-temperature) vent fluids decreased significantly within several years of eruptions in 1991 and 1992. After mid-1994, focused flow vents generally exhibited periods of relatively stable, slowly varying temperatures, with occasional high- and low-temperature excursions lasting days to weeks. One such positive temperature excursion was associated with a crustal cracking event. Another with both positive and negative excursions demonstrated a subsurface connection between adjacent focused flow and diffuse flow vents. Diffuse flow vents exhibit much greater temperature variability than adjacent higher-temperature vents. On timescales of a week or less, temperatures at a given position within a diffuse flow field often varied by 5°–10°C, synchronous with near-bottom currents dominated by tidal and inertial forcing. On timescales of a week and longer, diffuse flow temperatures varied slowly and incoherently among different vent fields. At diffuse flow vent sites, the conceptual model of a thermal boundary layer immediately above the seafloor explains many of the temporal and spatial temperature variations observed within a single vent field. The thermal boundary layer is a lens of warm water injected from beneath the seafloor that is mixed and distended by lateral near-bottom currents. The volume of the boundary layer is delineated by the position of mature communities of sessile (e.g., tubeworms) and relatively slow-moving organisms (e.g., mussels). Vertical flow rates of hydrothermal fluids exiting the seafloor at diffuse vents are less than lateral flow rates of near-bottom currents (5–10 cm/s). The presence of a subsurface, shallow reservoir of warm hydrothermal fluids can explain differing temperature behaviors of adjacent diffuse flow and focused flow vents at 9°50′N. Different average temperatures and daily temperature ranges are explained by variable amounts of mixing of hydrothermal fluids with ambient seawater through subsurface conduits that have varying lateral permeability.Field and shore-based analyses have been supported by the National Science Foundation (OCE-0096468, OCE-8917311, OCE-9217026, OCE-9302205, OCE-0327261), the Woods Hole Oceanographic Institution's Vetlesen Fund and W. A. Clark Senior Scientist Chair (DJF), and the Devonshire Foundation (TMS)
Effect of a magnetic field on the long-range magnetic order in insulating Nd2CuO4, nonsuperconducting and superconducting Nd1.85Ce0.15CuO4
We have measured the effect of a c-axis aligned magnetic field on the
long-range magnetic order of insulating Nd2CuO4, as-grown nonsuperconducting
and superconducting Nd1.85Ce0.15CuO4. On cooling from room temperature, Nd2CuO4
goes through a series of antiferromagnetic (AF) phase transitions with
different noncollinear spin structures. In all phases of Nd2CuO4, we find that
the applied c-axis field induces a canting of the AF order but does not alter
the basic zero-field noncollinear spin structures. Similar behavior is also
found in as-grown nonsuperconducting Nd1.85Ce0.15CuO4. These results contrast
dramatically with those of superconducting Nd1.85Ce0.15CuO4, where a c-axis
aligned magnetic field induces a static, anomalously conducting, long-range
ordered AF state. We confirm that the annealing process necessary to make
superconducting Nd1.85Ce0.15CuO4 also induces epitaxial, three-dimensional
long-range ordered cubic (Nd,Ce)2O3 as an impurity phase. In addition, the
annealing process makes a series of quasi two-dimensional superlattice
reflections associated with lattice distortions of Nd1.85Ce0.15CuO4 in the CuO2
plane. While the application of a magnetic field will induce a net moment in
the impurity phase, we determine its magnitude and eliminate this as a
possibility for the observed magnetic field-induced effect in superconducting
Nd1.85Ce0.15CuO4.Comment: 12 pages, 10 figures, to be published in Phys. Rev.
Placenta-specific methylation of the vitamin D 24-hydroxylase gene: implications for feedback autoregulation of active vitamin D levels at the fetomaternal interface
Plasma concentrations of biologically active vitamin D (1,25-
(OH)2D) are tightly controlled via feedback regulation of renal
1-hydroxylase (CYP27B1; positive) and 24-hydroxylase
(CYP24A1; catabolic) enzymes. In pregnancy, this regulation is
uncoupled, and 1,25-(OH)2D levels are significantly elevated,
suggesting a role in pregnancy progression. Epigenetic regulation
of CYP27B1 and CYP24A1 has previously been described in
cell and animal models, and despite emerging evidence for a
critical role of epigenetics in placentation generally, little is
known about the regulation of enzymes modulating vitamin D
homeostasis at the fetomaternal interface. In this study, we
investigated the methylation status of genes regulating vitamin
D bioavailability and activity in the placenta. No methylation of
the VDR (vitamin D receptor) and CYP27B1 genes was found in
any placental tissues. In contrast, the CYP24A1 gene is methylated
in human placenta, purified cytotrophoblasts, and primary
and cultured chorionic villus sampling tissue. No methylation
was detected in any somatic human tissue tested. Methylation
was also evident in marmoset and mouse placental tissue. All
three genes were hypermethylated in choriocarcinoma cell
lines, highlighting the role of vitaminDderegulation in this cancer.
Gene expression analysis confirmed a reduced capacity for
CYP24A1 induction with promoter methylation in primary cells
and in vitro reporter analysis demonstrated that promoter
methylation directly down-regulates basal promoter activity
and abolishes vitamin D-mediated feedback activation. This
study strongly suggests that epigenetic decoupling of vitamin D
feedback catabolism plays an important role in maximizing
active vitamin D bioavailability at the fetomaternal interface
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