1,299 research outputs found
Exciton entanglement in two coupled semiconductor microcrystallites
Entanglement of the excitonic states in the system of two coupled
semiconductor microcrystallites, whose sizes are much larger than the Bohr
radius of exciton in bulk semiconductor but smaller than the relevant optical
wavelength, is quantified in terms of the entropy of entanglement. It is
observed that the nonlinear interaction between excitons increases the maximum
values of the entropy of the entanglement more than that of the linear coupling
model. Therefore, a system of two coupled microcrystallites can be used as a
good source of entanglement with fixed exciton number. The relationship between
the entropy of the entanglement and the population imbalance of two
microcrystallites is numerically shown and the uppermost envelope function for
them is estimated by applying the Jaynes principle.Comment: 16 pages, 6 figure
A comparative study of relative entropy of entanglement, concurrence and negativity
The problem of ordering of two-qubit states imposed by relative entropy of
entanglement (E) in comparison to concurrence (C) and negativity (N) is
studied. Analytical examples of states consistently and inconsistently ordered
by the entanglement measures are given. In particular, the states for which any
of the three measures imposes order opposite to that given by the other two
measures are described. Moreover, examples are given of pairs of the states,
for which (i) N'=N'' and C'=C'' but E' is different from E'', (ii) N'=N'' and
E'=E'' but C' differs from C'', (iii) E'=E'', N'C'', or (iv) states
having the same E, C, and N but still violating the
Bell-Clauser-Horne-Shimony-Holt inequality to different degrees.Comment: 8 pages, 7 figures, final versio
Localized D-dimensional global k-defects
We explicitly demonstrate the existence of static global defect solutions of
arbitrary dimensionality whose energy does not diverge at spatial infinity, by
considering maximally symmetric solutions described by an action with
non-standard kinetic terms in a D+1 dimensional Minkowski space-time. We
analytically determine the defect profile both at small and large distances
from the defect centre. We verify the stability of such solutions and discuss
possible implications of our findings, in particular for dark matter and charge
fractionalization in graphene.Comment: 6 pages, published versio
Institutional capacity for health systems research in East and Central African Schools of Public Health: strengthening human and financial resources
BACKGROUND: Despite its importance in providing evidence for health-related policy and decision-making, an insufficient amount of health systems research (HSR) is conducted in low-income countries (LICs). Schools of public health (SPHs) are key stakeholders in HSR. This paper, one in a series of four, examines human and financial resources capacities, policies and organizational support for HSR in seven Africa Hub SPHs in East and Central Africa.
METHODS: Capacity assessment done included document analysis to establish staff numbers, qualifications and publications; self-assessment using a tool developed to capture individual perceptions on the capacity for HSR and institutional dialogues. Key informant interviews (KIIs) were held with Deans from each SPH and Ministry of Health and non-governmental officials, focusing on perceptions on capacity of SPHs to engage in HSR, access to funding, and organizational support for HSR.
RESULTS: A total of 123 people participated in the self-assessment and 73 KIIs were conducted. Except for the National University of Rwanda and the University of Nairobi SPH, most respondents expressed confidence in the adequacy of staffing levels and HSR-related skills at their SPH. However, most of the researchers operate at individual level with low outputs. The average number of HSR-related publications was only <1 to 3 per staff member over a 6-year period with most of the publications in international journals. There is dependency on external funding for HSR, except for Rwanda, where there was little government funding. We also found that officials from the Ministries of Health often formulate policy based on data generated through ad hoc technical reviews and consultancies, despite their questionable quality.
CONCLUSIONS: There exists adequate skilled staff for HSR in the SPHs. However, HSR conducted by individuals, fuelled by Ministries’ of Health tendency to engage individual researchers, undermines institutional capacity. This study underscores the need to form effective multidisciplinary teams to enhance research of immediate and local relevance. Capacity strengthening in the SPH needs to focus on knowledge translation and communication of findings to relevant audiences. Advocacy is needed to influence respective governments to allocate adequate funding for HSR to avoid donor dependency that distorts local research agenda.DFI
Fasciola hepatica Gastrodermal Cells Selectively Release Extracellular Vesicles via a Novel Atypical Secretory Mechanism
Publication history: Accepted - 12 May, 2022; Published - 15 may 2022.The liver fluke, Fasciola hepatica, is an obligate blood-feeder, and the gastrodermal cells of
the parasite form the interface with the host’s blood. Despite their importance in the host–parasite
interaction, in-depth proteomic analysis of the gastrodermal cells is lacking. Here, we used laser
microdissection of F. hepatica tissue sections to generate unique and biologically exclusive tissue
fractions of the gastrodermal cells and tegument for analysis by mass spectrometry. A total of
226 gastrodermal cell proteins were identified, with proteases that degrade haemoglobin being the
most abundant. Other detected proteins included those such as proton pumps and anticoagulants
which maintain a microenvironment that facilitates digestion. By comparing the gastrodermal cell
proteome and the 102 proteins identified in the laser microdissected tegument with previously
published tegument proteomic datasets, we showed that one-quarter of proteins (removed by freeze–
thaw extraction) or one-third of proteins (removed by detergent extraction) previously identified
as tegumental were instead derived from the gastrodermal cells. Comparative analysis of the laser
microdissected gastrodermal cells, tegument, and F. hepatica secretome revealed that the gastrodermal
cells are the principal source of secreted proteins, as well as showed that both the gastrodermal cells
and the tegument are likely to release subpopulations of extracellular vesicles (EVs). Microscopical
examination of the gut caeca from flukes fixed immediately after their removal from the host bile
ducts showed that selected gastrodermal cells underwent a progressive thinning of the apical plasma
membrane which ruptured to release secretory vesicles en masse into the gut lumen. Our findings
suggest that gut-derived EVs are released via a novel atypical secretory route and highlight the
importance of the gastrodermal cells in nutrient acquisition and possible immunomodulation by
the parasite.This work was supported by a grant to M.W.R. (BB/L019612/1) from the Biotechnology and
Biological Sciences Research Council (BBSRC). A.P.S.B. was supported by a postgraduate studentship
from the Department for the Economy (DfE) Northern Ireland
Testing new physics with the electron g-2
We argue that the anomalous magnetic moment of the electron (a_e) can be used
to probe new physics. We show that the present bound on new-physics
contributions to a_e is 8*10^-13, but the sensitivity can be improved by about
an order of magnitude with new measurements of a_e and more refined
determinations of alpha in atomic-physics experiments. Tests on new-physics
effects in a_e can play a crucial role in the interpretation of the observed
discrepancy in the anomalous magnetic moment of the muon (a_mu). In a large
class of models, new contributions to magnetic moments scale with the square of
lepton masses and thus the anomaly in a_mu suggests a new-physics effect in a_e
of (0.7 +- 0.2)*10^-13. We also present examples of new-physics theories in
which this scaling is violated and larger effects in a_e are expected. In such
models the value of a_e is correlated with specific predictions for processes
with violation of lepton number or lepton universality, and with the electric
dipole moment of the electron.Comment: 34 pages, 7 figures. Minor changes and references adde
Quantum optics in the phase space - A tutorial on Gaussian states
In this tutorial, we introduce the basic concepts and mathematical tools
needed for phase-space description of a very common class of states, whose
phase properties are described by Gaussian Wigner functions: the Gaussian
states. In particular, we address their manipulation, evolution and
characterization in view of their application to quantum information.Comment: Tutorial. 23 pages, 1 figure. Updated version accepted for
publication in EPJ - ST devoted to the memory of Federico Casagrand
Charged-Lepton Flavour Physics
This writeup of a talk at the 2011 Lepton-Photon symposium in Mumbai, India,
summarises recent results in the charged-lepton flavour sector. I review
searches for charged-lepton flavour violation, lepton electric dipole moments
and flavour-conserving CP violation. I also discuss recent progress in
tau-lepton physics and in the Standard Model prediction of the muon anomalous
magnetic moment.Comment: Presented at Lepton-Photon 2011, Mumbai, India; 23 pages, 14 figure
Safety and acceptability of an organic light-emitting diode sleep mask as a potential therapy for retinal disease
Purpose The purpose of the study was to study the effect of an organic light-emitting diode sleep mask on daytime alertness, wellbeing, and retinal structure/function in healthy volunteers and in diabetic macular oedema (DMO). Patients and methods Healthy volunteers in two groups, 18–30 yrs (A), 50–70 yrs (B) and people with DMO (C) wore masks (504 nm wavelength; 80 cd/m2 luminance; ≤8 h) nightly for 3 months followed by a 1-month recovery period. Changes from baseline were measured for (means): psychomotor vigilance task (PVT) (number of lapses (NL), response time (RT)), sleep, depression, psychological wellbeing (PW), visual acuity, contrast sensitivity, colour, electrophysiology, microperimetry, and retinal thickness on OCT. Results Of 60 participants, 16 (27%) withdrew, 8 (13%) before month 1, due to sleep disturbances and mask intolerance. About 36/55 (65%) who continued beyond month 1 reported ≥1 adverse event. At month 3 mean PVT worsened in Group A (RT (7.65%, P<0.001), NL (43.3%, P=0.005)) and mean PW worsened in all groups (A 28.0%, P=0.01, B 21.2%, P=0.03, C 12.8%, P<0.05). No other clinically significant safety signal was detected. Cysts reduced/resolved in the OCT subfield of maximal pathology in 67% Group C eyes. Thinning was greater at 3 and 4 months for greater baseline thickness (central subfield P<0.001, maximal P<0.05). Conclusion Sleep masks showed no major safety signal apart from a small impairment of daytime alertness and a moderate effect on wellbeing. Masks were acceptable apart from in some healthy participants. Preliminary data suggest a beneficial effect on retinal thickness in DMO. This novel therapeutic approach is ready for large clinical trials
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