85 research outputs found
Teleoftalmología para el cribado de Retinopatía Diabética en un área de salud integrada
[Resumen]
INTRODUCCIÓN: La Retinopatía Diabética representa la primera causa de ceguera entre la
población activa en los paises desarrollados, con un elevado coste socio-sanitario por su
alta prevalencia y repercusión en la calidad de vida. La detección precoz de los pacientes
con retinopatía susceptible de tratamiento efectivo disminuye la incidencia de complicaciones
oculares graves y pérdida visual severa. La Teleoftalmología mediante realización
de retinografías en los Centros de Salud de Atención Primaria es un método consolidado
para el cribado.
OBJETIVOS: Conocer la efectividad de un programa de Teleoftalmología para el cribado de
la Retinopatía Diabética, evaluar el impacto sobre la demanda asistencial e identificar las
limitaciones para proponer medidas que mejoren la calidad.
METODOLOGÍA: Estudio observacional retrospectivo de la población de un área sanitaria
integrada susceptible de cribado en Atención Primaria entre 2010-2014.
RESULTADOS: El porcentaje medio de cribado por profesional se situa en el 24,65% y el
ratio teleconsultas/retinografías para todo el área en el 65,36%. La principal barrera al
cribado percibida fue en el procesamiento informático de las imágenes (75,8%).
CONCLUSIONES: El impacto del programa de cribado ha sido la disminución de derivaciones
a consulta presencial de oftalmología, priorización de la patología y gran mejora
de la accesibilidad mediante teleconsulta en los centros con retinógrafo.[Resumo]
INTRODUCIÓN: A Retinopatía Diabética representa a primeira causa de cegueira entre a
poboación activa nos paises desenvolvidos, cun elevado custo socio-sanitario pola súa alta
prevalencia e repercusión na calidade de vida. A detección precoz dos pacientes con retinopatía
susceptible de tratamento efectivo diminúe a incidencia de complicacións oculares
graves e perda visual severa. A Teleoftalmoloxía mediante realización de retinografías
nos Centros de Saúde de Atención Primaria é un método consolidado para o cribado.
OBXECTIVOS: Coñecer a efectividade dun programa de Teleoftalmoloxía para o cribado
da Retinopatía Diabética, avaliar o impacto sobre a demanda asistencial e identificar as
limitacións para propoñer medidas que melloren a calidade.
METODOLOXÍA: Estudo observacional retrospectivo da poboación dunha área sanitaria integrada
susceptible de cribado en Atención Primaria entre 2010-2014.
RESULTADOS: A porcentaxe media de cribado por profesional foi do 24,65% e o ratio teleconsultas/
retinografías para todo a área foi do 65,36%. A principal barreira ao cribado
percibida foi o procesamento informático das imaxes (75,8%).
CONCLUSIÓNS: O impacto do programa de cribado foi a diminución de derivacións a consulta
presencial de oftalmoloxía, priorizacion da patoloxía e gran mellora da accesibilidade
mediante teleconsulta nos centros con retinógrafo.[Abstract]
INTRODUCTION: Diabetic retinopathy is the leading cause of blindness among the working
population in developed countries, with high social and health costs for its high prevalence
and impact on quality of life. Early detection of patients with retinopathy susceptible
effective treatment reduces the incidence of serious eye complications and severe visual
loss. The Teleophthalmology by performing retinographies in primary care centers is an
established method for screening.
OBJECTIVES: To determine the effectiveness of a Teleophthalmology programme for screening
diabetic retinopathy, assess the impact on the demand for care and identify constraints
to propose measures to improve quality.
METHODS: Retrospective observational study in a susceptible population for screening in
Primary Care in a health integrated area from 2010 to 2014.
RESULTS: The mean percentage of screening by professional was 24.65% and teleconsultation
/ retinographies ratio for the whole area was 65.36%. The main perceived barrier to
screening has been the computer processing of the images (75.8%).
CONCLUSIONS: The impact of the screening program has been decrease of referrals to ophthalmology, prioritization of pathology and greatly improved accessibility through teleconsultation
in centers with retinograph
Constraining the Ratio in TeV Cosmic Rays with Observations of the Moon Shadow by HAWC
An indirect measurement of the antiproton flux in cosmic rays is possible as
the particles undergo deflection by the geomagnetic field. This effect can be
measured by studying the deficit in the flux, or shadow, created by the Moon as
it absorbs cosmic rays that are headed towards the Earth. The shadow is
displaced from the actual position of the Moon due to geomagnetic deflection,
which is a function of the energy and charge of the cosmic rays. The
displacement provides a natural tool for momentum/charge discrimination that
can be used to study the composition of cosmic rays. Using 33 months of data
comprising more than 80 billion cosmic rays measured by the High Altitude Water
Cherenkov (HAWC) observatory, we have analyzed the Moon shadow to search for
TeV antiprotons in cosmic rays. We present our first upper limits on the
fraction, which in the absence of any direct measurements, provide
the tightest available constraints of on the antiproton fraction for
energies between 1 and 10 TeV.Comment: 10 pages, 5 figures. Accepted by Physical Review
Very high energy particle acceleration powered by the jets of the microquasar SS 433
SS 433 is a binary system containing a supergiant star that is overflowing
its Roche lobe with matter accreting onto a compact object (either a black hole
or neutron star). Two jets of ionized matter with a bulk velocity of
extend from the binary, perpendicular to the line of sight, and
terminate inside W50, a supernova remnant that is being distorted by the jets.
SS 433 differs from other microquasars in that the accretion is believed to be
super-Eddington, and the luminosity of the system is erg
s. The lobes of W50 in which the jets terminate, about 40 pc from the
central source, are expected to accelerate charged particles, and indeed radio
and X-ray emission consistent with electron synchrotron emission in a magnetic
field have been observed. At higher energies (>100 GeV), the particle fluxes of
rays from X-ray hotspots around SS 433 have been reported as flux
upper limits. In this energy regime, it has been unclear whether the emission
is dominated by electrons that are interacting with photons from the cosmic
microwave background through inverse-Compton scattering or by protons
interacting with the ambient gas. Here we report TeV -ray observations
of the SS 433/W50 system where the lobes are spatially resolved. The TeV
emission is localized to structures in the lobes, far from the center of the
system where the jets are formed. We have measured photon energies of at least
25 TeV, and these are certainly not Doppler boosted, because of the viewing
geometry. We conclude that the emission from radio to TeV energies is
consistent with a single population of electrons with energies extending to at
least hundreds of TeV in a magnetic field of ~micro-Gauss.Comment: Preprint version of Nature paper. Contacts: S. BenZvi, B. Dingus, K.
Fang, C.D. Rho , H. Zhang, H. Zho
Real-Time PCR Improves Helicobacter pylori Detection in Patients with Peptic Ulcer Bleeding
Background and aims: Histological and rapid urease tests to detect H. pylori in biopsy specimens obtained during peptic ulcer bleeding episodes (PUB) often produce false-negative results. We aimed to examine whether immunohistochemistry and real-time PCR can improve the sensitivity of these biopsies. Patients and Methods: We selected 52 histology-negative formalin-fixed paraffin-embedded biopsy specimens obtained during PUB episodes. Additional tests showed 10 were true negatives and 42 were false negatives. We also selected 17 histology-positive biopsy specimens obtained during PUB to use as controls. We performed immunohistochemistry staining and real-time PCR for 16S rRNA, ureA, and 23S rRNA for H. pylori genes on all specimens. Results: All controls were positive for H. pylori on all PCR assays and immunohistochemical staining. Regarding the 52 initially negative biopsies, all PCR tests were significantly more sensitive than immunohistochemical staining (p<0.01). Sensitivity and specificity were 55% and 80% for 16S rRNA PCR, 43% and 90% for ureA PCR, 41% and 80% for 23S rRNA PCR, and 7% and 100% for immunohistochemical staining, respectively. Combined analysis of PCR assays for two genes were significantly more sensitive than ureA or 23S rRNA PCR tests alone (p<0.05) and marginally better than 16S rRNA PCR alone. The best combination was 16S rRNA+ureA, with a sensitivity of 64% and a specificity of 80%. Conclusions: Real-time PCR improves the detection of H. pylori infection in histology-negative formalin-fixed paraffin-embedded biopsy samples obtained during PUB episodes. The low reported prevalence of H. pylori in PUB may be due to the failure of conventional tests to detect infection
First HAWC Observations of the Sun Constrain Steady TeV Gamma-Ray Emission
Steady gamma-ray emission up to at least 200 GeV has been detected from the
solar disk in the Fermi-LAT data, with the brightest, hardest emission
occurring during solar minimum. The likely cause is hadronic cosmic rays
undergoing collisions in the Sun's atmosphere after being redirected from
ingoing to outgoing in magnetic fields, though the exact mechanism is not
understood. An important new test of the gamma-ray production mechanism will
follow from observations at higher energies. Only the High Altitude Water
Cherenkov (HAWC) Observatory has the required sensitivity to effectively probe
the Sun in the TeV range. Using three years of HAWC data from November 2014 to
December 2017, just prior to the solar minimum, we search for 1--100 TeV gamma
rays from the solar disk. No evidence of a signal is observed, and we set
strong upper limits on the flux at a few TeV cm
s at 1 TeV. Our limit, which is the most constraining result on TeV
gamma rays from the Sun, is of the theoretical maximum flux (based
on a model where all incoming cosmic rays produce outgoing photons), which in
turn is comparable to the Fermi-LAT data near 100 GeV. The prospects for a
first TeV detection of the Sun by HAWC are especially high during solar
minimum, which began in early 2018.Comment: 14 pages, 6 figures. See also companion paper 1808.05624. Accepted
for publication in Physical Review
Constraints on Spin-Dependent Dark Matter Scattering with Long-Lived Mediators from TeV Observations of the Sun with HAWC
We analyze the Sun as a source for the indirect detection of dark matter
through a search for gamma rays from the solar disk. Capture of dark matter by
elastic interactions with the solar nuclei followed by annihilation to
long-lived mediators can produce a detectable gamma-ray flux. We search three
years of data from the High Altitude Water Cherenkov Observatory and find no
statistically significant detection of TeV gamma-ray emission from the Sun.
Using this, we constrain the spin-dependent elastic scattering cross section of
dark matter with protons for dark matter masses above 1 TeV, assuming an
unstable mediator with a favorable lifetime. The results complement constraints
obtained from Fermi-LAT observations of the Sun and together cover WIMP masses
between 4 GeV and GeV. The cross section constraints for mediator decays
to gamma rays can be as strong as cm, which is more than
four orders of magnitude stronger than current direct-detection experiments for
1 TeV dark matter mass. The cross-section constraints at higher masses are even
better, nearly 7 orders of magnitude better than the current direct-detection
constraints for 100 TeV dark matter mass. This demonstration of sensitivity
encourages detailed development of theoretical models in light of these
powerful new constraints.Comment: 11 pages, 4 figures. See also companion paper 1808.05620. Accepted
for publication in Physical Review
Observation of Anisotropy of TeV Cosmic Rays with Two Years of HAWC
After two years of operation, the High-Altitude Water Cherenkov (HAWC)
Observatory has analyzed the TeV cosmic-ray sky over an energy range between
and TeV. The HAWC detector is a ground-based air-shower array
located at high altitude in the state of Puebla, Mexico. Using 300 light-tight
water tanks, it collects the Cherenkov light from the particles of extensive
air showers from primary gamma rays and cosmic rays. This detection method
allows for uninterrupted observation of the entire overhead sky (2~sr
instantaneous, 8.5~sr integrated) in the energy range from a few TeV to
hundreds of TeV. Like other detectors in the northern and southern hemisphere,
HAWC observes an energy-dependent anisotropy in the arrival direction
distribution of cosmic rays. The observed cosmic-ray anisotropy is dominated by
a dipole moment with phase and amplitude that slowly
rises in relative intensity from at 2 TeV to
around 30.3 TeV, above which the dipole decreases in strength. A significant
large-scale ( in angular extent) signal is also observed in the
quadrupole and octupole moments, and significant small-scale features are also
present, with locations and shapes consistent with previous observations.
Compared to previous measurements in this energy range, the HAWC cosmic-ray sky
maps improve on the energy resolution and fit precision of the anisotropy.
These data can be used in an effort to better constrain local cosmic-ray
accelerators and the intervening magnetic fields.Comment: 22 pages, 14 figures, 2 tables, submission to Ap
NEOTROPICAL XENARTHRANS: a data set of occurrence of xenarthran species in the Neotropics
Xenarthrans – anteaters, sloths, and armadillos – have essential functions for ecosystem maintenance, such as insect control and nutrient cycling, playing key roles as ecosystem engineers. Because of habitat loss and fragmentation, hunting pressure, and conflicts with 24 domestic dogs, these species have been threatened locally, regionally, or even across their full distribution ranges. The Neotropics harbor 21 species of armadillos, ten anteaters, and six sloths. Our dataset includes the families Chlamyphoridae (13), Dasypodidae (7), Myrmecophagidae (3), Bradypodidae (4), and Megalonychidae (2). We have no occurrence data on Dasypus pilosus (Dasypodidae). Regarding Cyclopedidae, until recently, only one species was recognized, but new genetic studies have revealed that the group is represented by seven species. In this data-paper, we compiled a total of 42,528 records of 31 species, represented by occurrence and quantitative data, totaling 24,847 unique georeferenced records. The geographic range is from the south of the USA, Mexico, and Caribbean countries at the northern portion of the Neotropics, to its austral distribution in Argentina, Paraguay, Chile, and Uruguay. Regarding anteaters, Myrmecophaga tridactyla has the most records (n=5,941), and Cyclopes sp. has the fewest (n=240). The armadillo species with the most data is Dasypus novemcinctus (n=11,588), and the least recorded for Calyptophractus retusus (n=33). With regards to sloth species, Bradypus variegatus has the most records (n=962), and Bradypus pygmaeus has the fewest (n=12). Our main objective with Neotropical Xenarthrans is to make occurrence and quantitative data available to facilitate more ecological research, particularly if we integrate the xenarthran data with other datasets of Neotropical Series which will become available very soon (i.e. Neotropical Carnivores, Neotropical Invasive Mammals, and Neotropical Hunters and Dogs). Therefore, studies on trophic cascades, hunting pressure, habitat loss, fragmentation effects, species invasion, and climate change effects will be possible with the Neotropical Xenarthrans dataset
Multi-messenger observations of a binary neutron star merger
On 2017 August 17 a binary neutron star coalescence candidate (later designated GW170817) with merger time 12:41:04 UTC was observed through gravitational waves by the Advanced LIGO and Advanced Virgo detectors. The Fermi Gamma-ray Burst Monitor independently detected a gamma-ray burst (GRB 170817A) with a time delay of ~1.7 s with respect to the merger time. From the gravitational-wave signal, the source was initially localized to a sky region of 31 deg2 at a luminosity distance of 40+8-8 Mpc and with component masses consistent with neutron stars. The component masses were later measured to be in the range 0.86 to 2.26 Mo. An extensive observing campaign was launched across the electromagnetic spectrum leading to the discovery of a bright optical transient (SSS17a, now with the IAU identification of AT 2017gfo) in NGC 4993 (at ~40 Mpc) less than 11 hours after the merger by the One- Meter, Two Hemisphere (1M2H) team using the 1 m Swope Telescope. The optical transient was independently detected by multiple teams within an hour. Subsequent observations targeted the object and its environment. Early ultraviolet observations revealed a blue transient that faded within 48 hours. Optical and infrared observations showed a redward evolution over ~10 days. Following early non-detections, X-ray and radio emission were discovered at the transient’s position ~9 and ~16 days, respectively, after the merger. Both the X-ray and radio emission likely arise from a physical process that is distinct from the one that generates the UV/optical/near-infrared emission. No ultra-high-energy gamma-rays and no neutrino candidates consistent with the source were found in follow-up searches. These observations support the hypothesis that GW170817 was produced by the merger of two neutron stars in NGC4993 followed by a short gamma-ray burst (GRB 170817A) and a kilonova/macronova powered by the radioactive decay of r-process nuclei synthesized in the ejecta
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