1,382 research outputs found
Longitudinal associations among relationship factors, partner change, and sexually transmitted infection acquisition in adolescent women
OBJECTIVES:
New sex partners put adolescents at increased risk for sexually transmitted infections (STIs), even when these sex partners are nonoverlapping. Although the risk of partner change is well described, little is known about its antecedents. We prospectively examined associations between relationship characteristics, partner change, and subsequent STI during intervals of "serial monogamy."
METHODS:
As part of a longitudinal study, 332 adolescent women were interviewed and tested for gonorrhea, chlamydia, and trichomonas every 3 months for up to just over 6 years. Interviews covered partner-specific relationship characteristics and sexual behaviors. The quarterly interval, a 3-month period bracketed by interviews and STI testing, was the unit of analysis. We examined associations among relationship factors, partner change, and subsequent STI using a series of mixed regression models, controlling for age, STI at Time 1, and condom nonuse.
RESULTS:
Age, lower relationship quality, and lower levels of partner closeness to friends and family predicted partner change from Time 1 to Time 2. In turn, partner change was associated with acquisition of a new STI at Time 2. Although relationship factors did not exert a direct effect on STI at Time 2, they improved partner change-STI model fit. Similar patterns were seen with each organism.
CONCLUSION:
Relationship factors drive partner change, which in turn contributes to STI acquisition. STI prevention research may need to focus on the relationship antecedents to partner change, in addition to the partner change itself
The Nature of Heavy Quasiparticles in Magnetically Ordered Heavy Fermions
The optical conductivity of the heavy fermions UPd2Al3 and UPt3 has been
measured in the frequency range from 10 GHz to 1.2 THz (0.04 meV to 5 meV) at
temperatures 1 K < T < 300 K. In both compounds a well pronounced pseudogap of
less than a meV develops in the optical response at low temperatures; we relate
this to the antiferromagnetic ordering. From the energy dependence of the
effective electronic mass and scattering rate we derive the energies essential
for the heavy quasiparticle. We find that the enhancement of the mass mainly
occurs below the energy which is related to magnetic correlations between the
local magnetic moments and the itinerant electrons. This implies that the
magnetic order in these compounds is the pre-requisite to the formation of the
heavy quasiparticle and eventually of superconductivity.Comment: RevTeX, 4 pages, 3 figures, email:
[email protected]
Correlation gap in the heavy-fermion antiferromagnet UPd_2Al_3
The optical properties of the heavy-fermion compound UPdAl have been
measured in the frequency range from 0.04 meV to 5 meV (0.3 to 40 cm) at
temperatures K. Below the coherence temperature K, the hybridization gap opens around 10 meV. As the temperature decreases
further ( K), a well pronounced pseudogap of approximately 0.2 meV
develops in the optical response; we relate this to the antiferromagnetic
ordering which occurs below K. The frequency dependent mass and
scattering rate give evidence that the enhancement of the effective mass mainly
occurs below the energy which is associated to the magnetic correlations
between the itinerant and localized 5f electrons. In addition to this
correlation gap, we observe a narrow zero-frequency conductivity peak which at
2 K is less than 0.1 meV wide, and which contains only a fraction of the
delocalized carriers. The analysis of the spectral weight infers a loss of
kinetic energy associated with the superconducting transition.Comment: RevTex, 15 pages, 7 figure
Gammaretrovirus-mediated correction of SCID-X1 is associated with skewed vector integration site distribution in vivo
We treated 10 children with X-linked SCID (SCID-X1) using gammaretrovirus-mediated gene transfer. Those with sufficient follow-up were found to have recovered substantial immunity in the absence of any serious adverse events up to 5 years after treatment. To determine the influence of vector integration on lymphoid reconstitution, we compared retroviral integration sites (RISs) from peripheral blood CD3(+) T lymphocytes of 5 patients taken between 9 and 30 months after transplantation with transduced CD34(+) progenitor cells derived from 1 further patient and I healthy donor. Integration occurred preferentially in gene regions on either side of transcription start sites, was clustered, and correlated with the expression level in CD34(+) progenitors during transduction. In contrast to those in CD34(+) cells, RISs recovered from engrafted CD3(+)T cells were significantly overrepresented within or near genes encoding proteins with kinase or transferase activity or involved in phosphorus metabolism. Although gross patterns of gene expression were unchanged in transduced cells, the divergence of RIS target frequency between transduced progenitor cells and post-thymic T lymphocytes indicates that vector integration influences cell survival, engraftment, or proliferation
Dynamical principles in neuroscience
Dynamical modeling of neural systems and brain functions has a history of success over the last half century. This includes, for example, the explanation and prediction of some features of neural rhythmic behaviors. Many interesting dynamical models of learning and memory based on physiological experiments have been suggested over the last two decades. Dynamical models even of consciousness now exist. Usually these models and results are based on traditional approaches and paradigms of nonlinear dynamics including dynamical chaos. Neural systems are, however, an unusual subject for nonlinear dynamics for several reasons: (i) Even the simplest neural network, with only a few neurons and synaptic connections, has an enormous number of variables and control parameters. These make neural systems adaptive and flexible, and are critical to their biological function. (ii) In contrast to traditional physical systems described by well-known basic principles, first principles governing the dynamics of neural systems are unknown. (iii) Many different neural systems exhibit similar dynamics despite having different architectures and different levels of complexity. (iv) The network architecture and connection strengths are usually not known in detail and therefore the dynamical analysis must, in some sense, be probabilistic. (v) Since nervous systems are able to organize behavior based on sensory inputs, the dynamical modeling of these systems has to explain the transformation of temporal information into combinatorial or combinatorial-temporal codes, and vice versa, for memory and recognition. In this review these problems are discussed in the context of addressing the stimulating questions: What can neuroscience learn from nonlinear dynamics, and what can nonlinear dynamics learn from neuroscience?This work was supported by NSF Grant No. NSF/EIA-0130708, and Grant No. PHY 0414174; NIH Grant No. 1 R01 NS50945 and Grant No. NS40110; MEC BFI2003-07276, and Fundación BBVA
SARS-CoV-2 in an immunocompromised host: convalescent plasma therapy and viral evolution elucidated by whole genome sequencing
The evolution of SARS-CoV-2 within immunocompromised hosts who fail to clear the virus over many months has been proposed as a route to the development of Variants of Concern (VoCs). We present a case of an immunocompromised male patient with a prolonged SARS-CoV-2 infection. During hospitalisation, 7 weeks after first diagnosis, his condition worsened to require continuous ventilation support. Resolution of symptoms was observed after convalescent plasma therapy. Whole genome sequencing of the virus showed Pango lineage B.1.221. Between the first sample and the second from bronchoalveolar lavage fluid 7 weeks later, we identified eight mutations, including minor variants, which could be used to estimate the chronology of mutations. This suggests an elevated mutation rate, in-host accumulation of mutations and further evidence for sources of VoCs. Prolonged SARS-CoV-2 infections in immunocompromised hosts increase the likelihood of hospital stays and morbidity, and also pose an increased risk to global public health
Clinical Presentation of Enterovirus D68 in a Swiss Pediatric University Center
Background
Enterovirus D68 (EV-D68) is responsible for millions of infections. In the last decade, there has been an increase in the number of children requiring hospital or critical care admission due to severe respiratory illness. Nevertheless, the epidemiological and clinical importance of EV-D68 infections remains unclear.
Objective
We aimed to determine the local prevalence of EV-D68 infection in pediatric patients and to characterize its clinical presentation and disease burden compared with non-EV-D68 enterovirus and human rhinovirus (RV) infections.
Study design
We performed a retrospective single-center study of children presenting with respiratory symptoms and positive respiratory panel polymerase chain reaction for EV/RV from November 2018 to December 2019. We tested EV/RV positive specimens with an EV-D68-specific polymerase chain reaction to discriminate EV-D68, non-EV-D68 and RV and compared their respective clinical presentation, outcomes and treatment.
Results
We identified 224 patients (median age 21 months), of which 16 (7%) were EV-D68 positive. They presented with cough (88%), wheezing (62%) and dyspnea (75%). EV-D68 infection had an odds ratio regarding pediatric respiratory severity-score of 11.6 relative to non-EV-D68 [confidence intervals (CI): 3.51–41.14], and of 9.9 (CI: 3.75–27.95) relative to RV. The fitted logistic regression showed that the odds of intensive care were 5 times more likely with EV-D68 than RV infection (CI: 1.32–19.28; P = 0.001). Patients with EV-D68 infections were more likely to receive medical support in the form of supplementary oxygen, antibiotics and steroids.
Conclusions
EV-D68 infection is associated with higher morbidity and a higher likelihood of intensive care treatment than non-EV-D68 and RV infections
SARFOS - Search And Rescue Forward Operation Support System
Mountain search and rescue in the Alps of Austria and Switzerland is a prominent and challenging example of emergency response tasks. Significant numbers of search and rescue operations are carried out every year. In Switzerland, the "Alpine Rettung" in 2001 served 12'739 mission hours in 431 missions. Of these, 8'193 hours were spent on search missions. 17'229 members served a total of 40'720 hours. Operating in small teams, rescue personnel have to be coordinated overlarge areas, often in rough terrain and adverse weather conditions. Additional assets like helicopters or reconnaissance planes are called in on demand. Operations control typically used a mobile command post (car or van), that is driven close to the area. Due to the number of such tasks and complexity of operations, often with human lives at stake, there is significant demand for assistance by state-of-the-art technology. Key tasks of support are, on the one hand, position, situation and intent reporting of field teams to operations control. On the other hand, operations control needs to forward to field teams operational orders and assistance information, e-g- actual visual or thermal overhead imagery. Thus, there is an important need to exchange data between field teams and operations control ! The purpose of the SARFOS project is to develop a so-called forward emergency response coordination and communication system using a combination of latest technology in the field of integrated satellite and terrestrial communication, navigation and information databases. The answer to the demand identified during requirements analysis is to define, implement and finally demonstrate a prototype system, designed especially for and in cooperation with key mountain rescue services
Impacts of the Tropical Pacific/Indian Oceans on the Seasonal Cycle of the West African Monsoon
The current consensus is that drought has developed in the Sahel during the second half of the twentieth century as a result of remote effects of oceanic anomalies amplified by local land–atmosphere interactions. This paper focuses on the impacts of oceanic anomalies upon West African climate and specifically aims to identify those from SST anomalies in the Pacific/Indian Oceans during spring and summer seasons, when they were significant. Idealized sensitivity experiments are performed with four atmospheric general circulation models (AGCMs). The prescribed SST patterns used in the AGCMs are based on the leading mode of covariability between SST anomalies over the Pacific/Indian Oceans and summer rainfall over West Africa. The results show that such oceanic anomalies in the Pacific/Indian Ocean lead to a northward shift of an anomalous dry belt from the Gulf of Guinea to the Sahel as the season advances. In the Sahel, the magnitude of rainfall anomalies is comparable to that obtained by other authors using SST anomalies confined to the proximity of the Atlantic Ocean. The mechanism connecting the Pacific/Indian SST anomalies with West African rainfall has a strong seasonal cycle. In spring (May and June), anomalous subsidence develops over both the Maritime Continent and the equatorial Atlantic in response to the enhanced equatorial heating. Precipitation increases over continental West Africa in association with stronger zonal convergence of moisture. In addition, precipitation decreases over the Gulf of Guinea. During the monsoon peak (July and August), the SST anomalies move westward over the equatorial Pacific and the two regions where subsidence occurred earlier in the seasons merge over West Africa. The monsoon weakens and rainfall decreases over the Sahel, especially in August.Peer reviewe
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