277 research outputs found
Gamma-ray signatures of cosmic ray acceleration, propagation, and confinement in the era of CTA
Galactic cosmic rays are commonly believed to be accelerated at supernova
remnants via diffusive shock acceleration. Despite the popularity of this idea,
a conclusive proof for its validity is still missing. Gamma-ray astronomy
provides us with a powerful tool to tackle this problem, because gamma rays are
produced during cosmic ray interactions with the ambient gas. The detection of
gamma rays from several supernova remnants is encouraging, but still does not
constitute a proof of the scenario, the main problem being the difficulty in
disentangling the hadronic and leptonic contributions to the emission. Once
released by their sources, cosmic rays diffuse in the interstellar medium, and
finally escape from the Galaxy. The diffuse gamma-ray emission from the
Galactic disk, as well as the gamma-ray emission detected from a few galaxies
is largely due to the interactions of cosmic rays in the interstellar medium.
On much larger scales, cosmic rays are also expected to permeate the
intracluster medium, since they can be confined and accumulated within clusters
of galaxies for cosmological times. Thus, the detection of gamma rays from
clusters of galaxies, or even upper limits on their emission, will allow us to
constrain the cosmic ray output of the sources they contain, such as normal
galaxies, AGNs, and cosmological shocks. In this paper, we describe the impact
that the Cherenkov Telescope Array, a future ground-based facility for
very-high energy gamma-ray astronomy, is expected to have in this field of
research.Comment: accepted to Astroparticle Physics, special issue on Physics with the
Cherenkov Telescope Arra
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Transplacental non-steroidal anti-inflammatory drugs versus expectant management in fetal Ebstein anomaly with circular shunt: Systematic review and meta-analysis.
Ebstein anomaly (EA) is a rare congenital cardiac malformation associated with high perinatal mortality. In this systematic review and meta-analysis, we aimed to investigate the outcomes of pregnancies affected by EA or tricuspid valve dysplasia (TVD) with circular shunt, focusing on two prenatal management approaches: (1) expectant management (EM) and (2) transplacental non-steroidal anti-inflammatory drugs (NSAID) therapy. We searched PubMed, Scopus, and Web of Science systematically from its inception until June 2023. The random-effect model was used to pool the data. Heterogeneity was assessed using the I2 value. Twenty-one studies with a total of 610 fetuses with EA/TVD with circular shunt were included in the synthesis, of which 17 studies (583 fetuses) were on EM and 4 studies (27 fetuses) used transplacental NSAID therapy. The NSAID group had higher rates of moderate to severe tricuspid regurgitation, hydrops, and pericardial effusion on prenatal ultrasound compared with the EM group. However, ductal constriction was achieved in 81% of NSAID cases, mitigating the disease pathophysiology, although 65% of them experienced oligohydramnios. Notably, the NSAID group showed significantly higher rates of live birth (86%) and survival to hospital discharge (89%) compared with the EM group (67% and 43%, respectively). Despite these promising results, it's important to acknowledge that the number of cases treated with NSAIDs was small, with limited safety data. Therefore, caution is advised in interpreting these findings, and patients considering NSAID therapy should be informed about these limitations. Future multicenter studies are necessary to further explore the safety and effectiveness of NSAID therapy in this particular population
The effect of tablet containing Boswellia serrata and Melisa officinalis extract on older adults' memory: A randomized controlled trial
Abstract
Background
Memory deficits and age-related memory loss are currently two significant concerns in older adults. In Iranian herbal medicine, there are some prescriptions for memory improvement.
Objective
This study was designed to investigate the effect of tablet containing Boswellia serrata (BS) extract and Mellisa officinalis (MO) extract on memory of the older adults.
Method
This is a randomized, parallel, double-blind, placebo-controlled clinical trial that performed among 70 older adults who referred to healthcare centers of Kashan University of Medical Sciences, Iran. Subjects were randomly assigned to receive either tablets (nâŻ=âŻ35) or placebo (nâŻ=âŻ35) for a month (nâŻ=âŻ30). Data were collected using a demographic questionnaire and the Wechsler Memory Scale-Revised (WMS-R). Data were analyzed using Chi-square, independent-samples t-tests, paired t-test, repeated measure ANOVA, and ANCOVA using SPSS v13.
Result
Participants' baseline characteristics were similar in the two groups. The study was completed by 53 participants. However, as the analysis was based on an intention-to treat approach, all 70 older adults were included in the final analysis. Comparison of the two groups with showed that the total scores of the WMS-R and the subscales, including auditory immediate, immediate memory, visual immediate and working memory, were increased after consumption of the containing BS and MO tablets (pâŻ<âŻ0.0001).
Conclusion
The BS and MO tablet in older adults can be beneficial on improvement of memory. This is still necessary to investigate effects and durability of the tablets on older adults with memory impairments in future studies.
Keywords
Boswellia serrata Older adult Mellisa officinalis Memor
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Perinatal outcomes following fetoscopic laser surgery for early twin-to-twin transfusion syndrome: Systematic review and meta-analysis.
INTRODUCTION: Our objective was to investigate outcomes in twin-to-twin transfusion syndrome (TTTS) treated with fetoscopic laser surgery (FLS) at <18âweeks vs â„18âweeks, and to conduct subgroup analysis of TTTS with FLSâat <16âweeks vs 16-18âweeks. MATERIAL AND METHODS: PubMed, Scopus and Web of Science were searched systematically from inception until May 2023. Primary outcome was survival, and secondary outcomes included preterm premature rupture of membranes (PPROM), preterm birth and gestational age (GA) at delivery. RESULTS: Nine studies encompassing 1691 TTTS pregnancies were included. TTTS stage III was significantly more common in TTTS pregnancies treated with FLS at <18âweeks (odds ratio [OR] 2.84, 95% confidence interval [CI] 1.24-6.54), and procedure duration was shorter at <18âweeks (MD -5.27âminutes, 95% CI -9.19 to -1.34). GA at delivery was significantly earlier in TTTS pregnancies treated with FLS at <18âweeks (MD -3.12âweeks, 95% CI -6.11 to -0.13). There were no significant differences in outcomes, including PPROM, PPROMâat <7âdays post-FLS, preterm birth at <28 and <32âweeks, delivery at <7âdays post-FLS, and survival outcomes, including fetal demise, live birth and neonatal survival. Similarly, TTTS stage III was more common in TTTS with FLS at <16âweeks than at 16-18âweeks (OR 2.95, 95% CI 1.62-5.35), with no significant differences in the aforementioned outcomes. CONCLUSIONS: In early TTTS treated with FLS, outcomes were comparable between those treated at <18âweeks compared with â„18âweeks except for GA at delivery, which was 3âweeks earlier. In the subset treated at <16âweeks vs 16-18âweeks, the procedure was feasible without an increased risk of very early preterm birth or perinatal mortality
A slow gravity compensated Atom Laser
We report on a slow guided atom laser beam outcoupled from a Bose-Einstein
condensate of 87Rb atoms in a hybrid trap. The acceleration of the atom laser
beam can be controlled by compensating the gravitational acceleration and we
reach residual accelerations as low as 0.0027 g. The outcoupling mechanism
allows for the production of a constant flux of 4.5x10^6 atoms per second and
due to transverse guiding we obtain an upper limit for the mean beam width of
4.6 \mu\m. The transverse velocity spread is only 0.2 mm/s and thus an upper
limit for the beam quality parameter is M^2=2.5. We demonstrate the potential
of the long interrogation times available with this atom laser beam by
measuring the trap frequency in a single measurement. The small beam width
together with the long evolution and interrogation time makes this atom laser
beam a promising tool for continuous interferometric measurements.Comment: 7 pages, 8 figures, to be published in Applied Physics
Binaries with the eyes of CTA
The binary systems that have been detected in gamma rays have proven very
useful to study high-energy processes, in particular particle acceleration,
emission and radiation reprocessing, and the dynamics of the underlying
magnetized flows. Binary systems, either detected or potential gamma-ray
emitters, can be grouped in different subclasses depending on the nature of the
binary components or the origin of the particle acceleration: the interaction
of the winds of either a pulsar and a massive star or two massive stars;
accretion onto a compact object and jet formation; and interaction of a
relativistic outflow with the external medium. We evaluate the potentialities
of an instrument like the Cherenkov telescope array (CTA) to study the
non-thermal physics of gamma-ray binaries, which requires the observation of
high-energy phenomena at different time and spatial scales. We analyze the
capability of CTA, under different configurations, to probe the spectral,
temporal and spatial behavior of gamma-ray binaries in the context of the known
or expected physics of these sources. CTA will be able to probe with high
spectral, temporal and spatial resolution the physical processes behind the
gamma-ray emission in binaries, significantly increasing as well the number of
known sources. This will allow the derivation of information on the particle
acceleration and emission sites qualitatively better than what is currently
available.Comment: 23 pages, 13 figures, accepted for publication in Astroparticle
Physics, special issue on Physics with the Cherenkov Telescope Arra
Active Galactic Nuclei under the scrutiny of CTA
Active Galactic Nuclei (hereafter AGN) produce powerful outflows which offer
excellent conditions for efficient particle acceleration in internal and
external shocks, turbulence, and magnetic reconnection events. The jets as well
as particle accelerating regions close to the supermassive black holes
(hereafter SMBH) at the intersection of plasma inflows and outflows, can
produce readily detectable very high energy gamma-ray emission. As of now, more
than 45 AGN including 41 blazars and 4 radiogalaxies have been detected by the
present ground-based gamma-ray telescopes, which represents more than one third
of the cosmic sources detected so far in the VHE gamma-ray regime. The future
Cherenkov Telescope Array (CTA) should boost the sample of AGN detected in the
VHE range by about one order of magnitude, shedding new light on AGN population
studies, and AGN classification and unification schemes. CTA will be a unique
tool to scrutinize the extreme high-energy tail of accelerated particles in
SMBH environments, to revisit the central engines and their associated
relativistic jets, and to study the particle acceleration and emission
mechanisms, particularly exploring the missing link between accretion physics,
SMBH magnetospheres and jet formation. Monitoring of distant AGN will be an
extremely rewarding observing program which will inform us about the inner
workings and evolution of AGN. Furthermore these AGN are bright beacons of
gamma-rays which will allow us to constrain the extragalactic infrared and
optical backgrounds as well as the intergalactic magnetic field, and will
enable tests of quantum gravity and other "exotic" phenomena.Comment: 28 pages, 23 figure
Measuring Sexual Performance: Development and Psychometric Properties of the Sexual Performance Questionnaire in Iranian People with Spinal Cord Injury
Sexual performance refers to activities served by sexual capacity and motivation. As a culturally sensitive issue, to date the scalar invariance of sexual performance has not been examined for Iranians with spinal cord injuries (SCIs). Aim: To develop and assess properties of an instrument evaluating sexual performance of an Iranian population with SCIs., in Brain and Spinal Cord Injury Research Center (BASIR), Neuroscience Institute, Tehran University of Medical Sciences, Tehran, Iran. Using multi-modal methods, we developed and assessed the Sexual Performance Questionnaire (SPQ). This included collecting expert opinions; engaging with patients with SCI referred to BASIR; pilot testing to assess the scale; and a formal investigation. Participants (men = 156, women = 58) completed the SPQ. Internal consistency and reliability were measured using Cronbachâs α coefficient. Content and face validity were examined by academic experts. Construct validity was assessed by examining convergent and discriminant validity. Finally, exploratory factor analysis was used to extract the factor structure of the questionnaire. The Cronbachâs α coefficient was 0.77. There was a significant (p = 0.04) correlation (r = â 0.23) between the SPQ score and age. Those with a partner scored higher (p = 0.001). We found three components: Spouse as initiator, self-initiation, and genital-oriented sex which accounted for 59 of the observed variance. The face and content validity was approved by an expert committee. The development and application of the 13-item SPQ provides a thorough understanding of sexual performance amongst persons with SCI. It facilitates the development of efficient sexual rehabilitation interventions and SCI-specific sexuality education programs. © 2020, Springer Science+Business Media, LLC, part of Springer Nature
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