7,484 research outputs found
Skin-derived dendritic cells acquire and degrade the scrapie agent following in vitro exposure
The accumulation of the scrapie agent in lymphoid tissues following inoculation via the skin is critical for efficient neuroinvasion, but how the agent is initially transported from the skin to the draining lymph node is not known. Langerhans cells (LCs) are specialized antigen-presenting cells that continually sample their microenvironment within the epidermis and transport captured antigens to draining lymph nodes. We considered LCs probable candidates to acquire and transport the scrapie agent after inoculation via the skin. XS106 cells are dendritic cells (DCs) isolated from mouse epidermis with characteristics of mature LC cells. To investigate the potential interaction of LCs with the scrapie agent XS106 cells were exposed to the scrapie agent in vitro. We show that XS106 cells rapidly acquire the scrapie agent following in vitro exposure. In addition, XS106 cells partially degrade the scrapie agent following extended cultivation. These data suggest that LCs might acquire and degrade the scrapie agent after inoculation via the skin, but data from additional experiments demonstrate that this ability could be lost in the presence of lipopolysaccharide or other immunostimulatory molecules. Our studies also imply that LCs would not undergo maturation following uptake of the scrapie agent in the skin, as the expression of surface antigens associated with LC maturation were unaltered following exposure. In conclusion, although LCs or DCs have the potential to acquire the scrapie agent within the epidermis our data suggest it is unlikely that they become activated and stimulated to transport the agent to the draining lymph node
Servant leadership as a driver of employee service performance: Test of a trickle-down model and its boundary conditions
Previous research has demonstrated the role of servant leadership, a leadership style emphasizing serving others, in promoting frontline employeesâ service performance. It is unclear, however, how servant leadership by leaders at different organizational levels would exert such an influence. Integrating insights from both social learning theory and the trickle-down paradigm of leadership, we develop a cross-level model in which we argue that servant leadership by high-level managers could cascade downward through the organizational hierarchy to influence frontline employeesâ service performance and that this trickle-down effect is contingent on the extent to which subordinates identify their leaders as embodying the organization. Using a matched sample of 92 supervisors and 568 frontline employees across 92 sub-branches of a large banking company, we found that servant leadership by high-level managers could indeed promote employeesâ in-role and extra-role service performance through its effect on low-level supervisorsâ servant leadership. We also found that this trickle-down effect was stronger when high-level managers and low-level supervisors were perceived by their subordinates as more fully embodying the organization. Implications, limitations and future directions are discussed
Enumeration of distinct mechanically stable disk packings in small systems
We create mechanically stable (MS) packings of bidisperse disks using an
algorithm in which we successively grow or shrink soft repulsive disks followed
by energy minimization until the overlaps are vanishingly small. We focus on
small systems because this enables us to enumerate nearly all distinct MS
packings. We measure the probability to obtain a MS packing at packing fraction
and find several notable results. First, the probability is highly
nonuniform. When averaged over narrow packing fraction intervals, the most
probable MS packing occurs at the highest and the probability decays
exponentially with decreasing . Even more striking, within each
packing-fraction interval, the probability can vary by many orders of
magnitude. By using two different packing-generation protocols, we show that
these results are robust and the packing frequencies do not change
qualitatively with different protocols.Comment: 4 pages, 3 figures, Conference Proceedings for X International
Workshop on Disordered System
Single Cut Integration
We present an analytic technique for evaluating single cuts for one-loop
integrands, where exactly one propagator is taken to be on shell. Our method
extends the double-cut integration formalism of one-loop amplitudes to the
single-cut case. We argue that single cuts give meaningful information about
amplitudes when taken at the integrand level. We discuss applications to the
computation of tadpole coefficients.Comment: v2: corrected typo in abstrac
A Systematic Review and Meta-Analysis of Symptoms of Anxiety, Depression, and Insomnia in Spain in the COVID-19 Crisis.
BACKGROUND: General population, frontline healthcare workers (HCWs), and adult students in Spain are at risk of anxiety, depression, and insomnia symptoms during the COVID-19 crisis. A meta-analysis of the individual studies on these symptoms would provide systematic evidence to aid policymakers and researchers in focusing on prevalence, risk, and best interventions. OBJECTIVE: This paper aims to be the first meta-analysis and systematic review to calculate the prevalence of anxiety, depression, and insomnia symptoms in Spain's adult population (general population, frontline healthcare workers (HCWs), and adult students) during the Covid-19 epidemic. METHOD: Random-effect meta-analysis was used to estimate the prevalence of anxiety, depression, and insomnia. RESULTS: The meta-analysis includes 28 studies with 38 individual samples in Spain. The pooled prevalence of anxiety symptoms in 22 studies comprising a sample population of 82,024 was 20% (95% CI: 15-25%), that of depression symptoms in 22 articles with a total sample comprising 82,890 individuals was 22% (95% CI: 18-28%), and that of insomnia symptoms in three articles with a sample population of 745 was 57% (95% CI: 48-66%. CONCLUSIONS: The accumulative evidence reveals that adults in Spain suffered higher prevalence rates of mental symptoms during the COVID-19 crisis, with a significantly higher rate relative to other countries such as China. Our synthesis also reveals a relative lack of studies on frontline and general HCWs in Spain
Influence of Lithium and Lanthanum Treatment on TiO2 Nanofibers and Their Application in n-i-p Solar Cells
The addition of cations to TiO2 photoelectrodes is routinely accepted as a route to enhance the performance of conventional nâiâp solar cells. However, this is typically achieved in multiple steps or by the incorporation of expensive and hydroscopic cationic precursors such as lithium bis(trifluoromethanesulfonyl)imide. In addition, it is often unclear as to whether the incorporation of such cation sources is inducing âdopingâ or simply transformed into cationic oxides on the surface of the photoelectrodes. In this study, TiO2 nanofibers were produced through a simple electrospinning technique and modified by introducing lithium and lanthanum precursors in one step. Our results show that the addition of both cations caused minimal substitutional or interstitial doping of TiO2. BrunauerâEmmettâTeller measurements showed that lanthanumâtreated TiO2 nanofibers had an increase in surface area, which even exceeded that of TiO2 P25 nanoparticles. Finally, treated and untreated TiO2 nanofibers were used in nâiâp solar cells. Photovoltaic characteristics revealed that lanthanum treatment was beneficial, whereas lithium treatment was found to be detrimental to the device performance for both dyeâsensitized and perovskite solar cells. The results discuss new fundamental understandings for two of the commonly incorporated cationic dopants in TiO2 photoelectrodes, lithium and lanthanum, and present a significant step forward in advancing the field of materials chemistry for photovoltaics
Pd Nanoparticles and Thin Films for Room Temperature Hydrogen Sensor
We report the application of palladium nanoparticles and thin films for hydrogen sensor. Electrochemically grown palladium particles with spherical shapes deposited on Si substrate and sputter deposited Pd thin films were used to detect hydrogen at room temperature. Grain size dependence of H2sensing behavior has been discussed for both types of Pd films. The electrochemically grown Pd nanoparticles were observed to show better hydrogen sensing response than the sputtered palladium thin films. The demonstration of size dependent room temperature H2sensing paves the ways to fabricate the room temperature metallic and metalâmetal oxide semiconductor sensor by tuning the size of metal catalyst in mixed systems. H2sensing by the Pd nanostructures is attributed to the chemical and electronic sensitization mechanisms
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