686 research outputs found
Spectroscopy of a fractional Josephson vortex molecule
In long Josephson junctions with multiple discontinuities of the Josephson
phase, fractional vortex molecules are spontaneously formed. At each
discontinuity point a fractional Josephson vortex carrying a magnetic flux
, Wb being the magnetic flux
quantum, is pinned. Each vortex has an oscillatory eigenmode with a frequency
that depends on and lies inside the plasma gap.
We experimentally investigate the dependence of the eigenfrequencies of a
two-vortex molecule on the distance between the vortices, on their topological
charge and on the bias current applied to the
Josephson junction. We find that with decreasing distance between vortices, a
splitting of the eigenfrequencies occurs, that corresponds to the emergence of
collective oscillatory modes of both vortices. We use a resonant microwave
spectroscopy technique and find good agreement between experimental results and
theoretical predictions.Comment: submitted to Phys. Rev.
Nanocoating with plant-derived pectins activates osteoblast response in vitro
Abstract: A new strategy to improve osseointegration of implants is to
stimulate adhesion of bone cells, bone matrix formation, and mineralization at
the implant surface by modifying surface coating on the nanoscale level.
Plant-derived pectins have been proposed as potential candidates for surface
nanocoating of orthopedic and dental titanium implants due to 1) their
osteogenic stimulation of osteoblasts to mineralize and 2) their ability to
control pectin structural changes. The aim of this study was to evaluate in
vitro the impact of the nanoscale plant-derived pectin Rhamnogalacturonan-I
(RG-I) from potato on the osteogenic response of murine osteoblasts. RG-I from
potato pulps was isolated, structurally modified, or left unmodified. Tissue
culture plates were either coated with modified RG-I or unmodified RG-I or â
as a control â left uncoated. The effect of nanocoating on mice osteoblast-
like cells MC3T3-E1 and primary murine osteoblast with regard to
proliferation, osteogenic response in terms of mineralization, and gene
expression of Runt-related transcription factor 2 (Runx2), alkaline phosphate
(Alpl), osteocalcin (Bglap), Îą-1 type I collagen (Col1a1), and receptor
activator of NF-ÎşB ligand (Rankl) were analyzed after 3, 7, 14, and 21 days,
respectively. Nanocoating with pectin RG-Is increased proliferation and
mineralization of MC3T3-E1 and primary osteoblast as compared to osteoblasts
cultured without nanocoating. Moreover, osteogenic transcriptional response of
osteoblasts was induced by nanocoating in terms of gene induction of Runx2,
Alpl, Bglap, and Col1a1 in a time-dependent manner â of note â to the highest
extent under the PA-coating condition. In contrast, Rankl expression was
initially reduced by nanocoating in MC3T3-E1 or remained unaltered in primary
osteoblast as compared to the uncoated controls. Our results showed that
nanocoating of implants with modified RG-I beneficially 1) supports
osteogenesis, 2) has the capacity to improve osseointegration of implants, and
is therefore 3) a potential candidate for nanocoating of bone implants
Observation of negative absolute resistance in a Josephson junction
We experimentally demonstrate the occurrence of negative absolute resistance
(NAR) up to about in response to an externally applied dc current
for a shunted Nb-Al/AlO-Nb Josephson junction, exposed to a microwave
current at frequencies in the GHz range. The realization (or not) of NAR
depends crucially on the amplitude of the applied microwave current.
Theoretically, the system is described by means of the resistively and
capacitively shunted junction model in terms of a moderately damped, classical
Brownian particle dynamics in a one-dimensional potential. We find excellent
agreement of the experimental results with numerical simulations of the model.Comment: 4 pages, 3 figures, submitted to Physical Revie
Acute tryptophan depletion in accordance with body weight: influx of amino acids across the bloodâbrain barrier
Acute tryptophan depletion (ATD) is a method of reducing central nervous serotonin (5-HT) synthesis in humans by administering an amino acid (AA) beverage lacking in tryptophan (TRP), the physiological precursor of 5-HT. However, to date, the use of conventional ATD protocols in children and adolescents was limited due to frequently observed side effects (e.g., vomiting and nausea). This study investigated the effects of diminished central nervous system 5-HT synthesis on plasma concentrations of relevant AAs and TRP influx into the brain in 24 healthy young adults using the ATD procedure Moja-De, a test protocol that has been used in preliminary research in youths. Twenty-four healthy participants received ATD and a TRP-balanced amino acid load (BAL) using a randomized double-blind within-subject crossover design. Plasma concentrations of the relevant AAs that compete with TRP on the same transport system were assessed at baseline and 90, 180, and 240Â min after ATD/BAL intake. TRP influx across the bloodâbrain barrier was calculated using MichaelisâMenten kinetics with a correction for multiple substrate competition, indicating a significant decrease in TRP influx into the central nervous system under Moja-De. ATD Moja-De decreased TRP influx into the brain and central nervous system 5-HT synthesis safely and effectively and was well tolerated, allowing it to be used in children and adolescents. Future research into other secondary, compensatory effects induced by ATD in patients with neuropsychiatric disorders and healthy populations is needed. ATD Moja-De allows this type of research with a focus on a developmental viewpoint. ELECTRONIC SUPPLEMENTARY MATERIAL: The online version of this article (doi:10.1007/s00702-012-0793-z) contains supplementary material, which is available to authorized users
COVID-19 mortality may be reduced among fully vaccinated solid organ transplant recipients.
BACKGROUND: Solid organ transplant (SOT) recipients are at increased risk for morbidity and mortality from COVID-19 due to their immunosuppressed state and reduced immunogenicity from COVID-19 mRNA vaccines. This investigation examined the association between COVID-19 mRNA vaccination status and mortality among SOT recipients diagnosed with COVID-19.
METHODS & FINDINGS: A retrospective, registry-based chart review was conducted investigating COVID-19 mortality among immunosuppressed solid organ transplant (SOT) recipients in a large metropolitan healthcare system in Houston, Texas, USA. Electronic health record data was collected from consecutive SOT recipients who received a diagnostic SARS-CoV-2 test between March 1, 2020, and October 1, 2021. The primary exposure was COVID-19 vaccination status at time of COVID-19 diagnosis. Patients were considered \u27fully vaccinated\u27 at fourteen days after completing their vaccine course. COVID-19 mortality within 60 days and intensive care unit admission within 30 days were primary and secondary endpoints, respectively. Among 646 SOT recipients who were diagnosed with COVID-19 at Houston Methodist Hospital between March 2020, and October 2021, 70 (10.8%) expired from COVID-19 within 60 days. Transplanted organs included 63 (9.8%) heart, 355 (55.0%) kidney, 108 (16.7%) liver, 70 (10.8%) lung, and 50 (7.7%) multi-organ. Increasing age was a risk factor for COVID-19 mortality, while vaccination within 180 days of COVID-19 diagnosis was protective in Cox proportional hazard models with hazard ratio 1.04 (95% CI: 1.01-1.06) and 0.31 (0.11-0.90), respectively). These findings were confirmed in the propensity score matched cohort between vaccinated and unvaccinated patients.
CONCLUSIONS: This investigation found COVID-19 mortality may be significantly reduced among immunosuppressed SOT recipients within 6 months following vaccination. These findings can inform vaccination policies targeting immunosuppressed populations worldwide
BETWEEN BROADCASTING POLITICAL MESSAGES AND INTERACTING WITH VOTERS
Politicians across Western democracies are increasingly adopting and experimenting with Twitter, particularly during election time. The purpose of this article is to investigate how candidates are using it during an election campaign. The aim is to create a typology of the various ways in which candidates behaved on Twitter. Our research, which included a content analysis of tweets (nâ=â26,282) from all twittering Conservative, Labour and Liberal Democrat candidates (nâ=â416) during the 2010 UK General Election campaign, focused on four aspects of tweets: type, interaction, function and topic. By examining candidates' twittering behaviour, the authors show that British politicians mainly used Twitter as a unidirectional form of communication. However, there were a group of candidates who used it to interact with voters by, for example, mobilizing, helping and consulting them, thus tapping into the potential Twitter offers for facilitating a closer relationship with citizens
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