95 research outputs found
The HIBEAM program: search for neutron oscillations at the ESS
With the construction of the European Spallation Source, a remarkable
opportunity has emerged to conduct high sensitivity searches for neutron
oscillations, including a first search for thirty years for free neutrons
converting to antineutrons. Furthermore, searches can be made for transitions
of neutrons and antineutrons to sterile neutron states. The HIBEAM program
provides an increase in sensitivity of an order of magnitude compared to
previous work.
The HIBEAM program corresponds to baryon number violation by one and two
units. The observation of a process satisfying a Sakharov condition addresses
the open question of the origin of the matter-antimatter asymmetry in the
Universe. Sterile neutron states would belong to a `dark' sector of particles
which may explain dark matter. As electrically neutral, meta-stable objects
that can be copiously produced and studied, neutrons represent an attractive
portal to a `dark' sector.
This paper describes the capability, design, infrastructure, and potential of
the HIBEAM program. This includes a dedicated beamline, neutron optical system,
magnetic shielding and control, and detectors for neutrons and antineutrons.Comment: 41 pages, 12 figure
Vitamin D deficiency contributes directly to the acute respiratory distress syndrome (ARDS)
Rationale: Vitamin D deficiency has been implicated as a pathogenic factor in sepsis and intensive therapy unit mortality but has not been assessed as a risk factor for acute respiratory distress syndrome (ARDS). Causality of these associations has never been demonstrated. Objectives: To determine if ARDS is associated with vitamin D deficiency in a clinical setting and to determine if vitamin D deficiency in experimental models of ARDS influences its severity. Methods: Human, murine and in vitro primary alveolar epithelial cell work were included in this study. Findings: Vitamin D deficiency (plasma 25(OH)D levels 600 genes. In a clinical setting, pharmacological repletion of vitamin D prior to oesophagectomy reduced the observed changes of in vivo measurements of alveolar capillary damage seen in deficient patients. Conclusions: Vitamin D deficiency is common in people who develop ARDS. This deficiency of vitamin D appears to contribute to the development of the condition, and approaches to correct vitamin D deficiency in patients at risk of ARDS should be developed
A comparative study of biomolecule and polymer surface modifications by a surface microdischarge
Cold atmospheric plasma (CAP) sources are attractive sources of reactive species with
promising industrial and biomedical applications, but an understanding of underlying
surface mechanisms is lacking. A kHz-powered surface microdischarge (SMD) operating with
N2/O2 mixtures was used to study the biological deactivation of
two immune-stimulating biomolecules: lipopolysaccharide (LPS) and peptidoglycan (PGN),
found in bacteria such as Escherichia coli and Staphylococcus
aureus, respectively. Model polymers were also studied to isolate specific
functional groups. Changes in the surface chemistry were measured to understand which
plasma-generated species and surface modifications are important for biological
deactivation. The overall goal of this work is to determine which effects of CAP treatment
are generic and which bonds are susceptible to attack. CAP treatment deactivated
biomolecules, oxidized surfaces, and introduced surface bound NO3. These effects can be
controlled by the N2 fraction in O2 and applied voltage and vary among different target
surfaces. The SMD was compared with an Ar/O2/N2-fed kHz-powered atmospheric pressure plasma jet and
showed much higher surface modifications and surface chemistry tunability compared to the
jet. Possible mechanisms are discussed and findings are compared with recent computational
investigations. Our results demonstrate the importance of long-lived plasma-generated
species and advance an atomistic understanding of CAP-surface interactions
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