332 research outputs found
Evaluation of Local Site Conditions Using Ambient Seismic Noise Recordings: A Case Study from Ankara, Turkey
This paper aims to investigate the site response of the sediment characteristics and to perform seismic hazard studies in Ankara, Turkey through conducting short-period noise recordings of microtremor measurements at 352 project site locations on the Upper Pliocene to Pleistocene fluvial and particularly Quaternary alluvial and terrace sediments in the Ankara basin. The spectral ratios relative to a firm site reference station (SSR) and the spectral ratio between the horizontal and vertical components (HVSR) of the microtremor measurements at the ground surface have been used to estimate the fundamental periods and the amplification factors of the site. The results of this study identified three main factors that influence site response, namely, the age of the near-surface deposits, the sediment thickness and the non-linear soil behavior. In particular, the HVSR results showed that the variation of the fundamental period map agreed well with the maximum value of the amplification as well as with the seismic sediment characteristics that provided satisfactory estimates of the site response of soft deposits
Optimizing the Access to Healthcare Services in Dense Refugee Hosting Urban Areas: A Case for Istanbul
With over 3.5 million refugees, Turkey continues to host the world's largest
refugee population. This introduced several challenges in many areas including
access to healthcare system. Refugees have legal rights to free healthcare
services in Turkey's public hospitals. With the aim of increasing healthcare
access for refugees, we looked at where the lack of infrastructure is felt the
most. Our study attempts to address these problems by assessing whether Migrant
Health Centers' locations are optimal. The aim of this study is to improve
refugees' access to healthcare services in Istanbul by improving the locations
of health facilities available to them. We used call data records provided by
Turk Telekom.Comment: version to submit for D4R competitio
EVALUATION OF SITE CHARACTERIZATIONS AND SITE EFFECTS OF THE ANKARA BASIN, TURKEY
ABSTRACT The purpose of this study is to assess the in-situ site characteristics and to perform seismic hazard studies of the Upper Pliocene to Pleistocene fluvial and Quaternary alluvial and terrace deposits located towards the west of Ankara. Based on a general engineering geological, geotechnical and seismic characterization of the site, site classification systems were assigned for seismic hazard evaluations. Then, short-period noise recordings of the microtremor measurements at the ground surface have been used to estimate the site response of the site. This research mainly focuses on the development of a methodology to integrate the various components necessary for a regional multihazard seismic risk assessment that includes consideration of hazards due to local site effects. These tasks have been fulfilled through the development of an engineering database that was obtained from invasive and non-invasive explorations at the study area. Hence, the engineering geological and geotechnical site characterization studies have been compiled; and geophysical site characterization studies have been performed, particularly in the Quaternary sediments of the Ankara basin. By using all of these studies, hazard assessment maps (i.e., site classification map and site period map) and a seismic zonation map of Ankara basin, Turkey were developed along with discussing the consequences of the seismic hazards
Current clinician perspective on non-vitamin K antagonist oral anticoagulant use in challenging clinical cases.
OBJECTIVE: The evolution of non-vitamin K antagonist anticoagulants (NOACs) has changed the horizon of stroke prevention in atrial fibrillation (SPAF). All 4 NOACs have been tested against dose-adjusted warfarin in well-designed, pivotal, phase III, randomized, controlled trials (RCTs) and were approved by regulatory authorities for an SPAF indication. However, as traditional RCTs, these trials have important weaknesses, largely related to their complex structure and patient participation, which was limited by strict inclusion and extensive exclusion criteria. In the real world, however, clinicians are often faced with complex, multimorbid patients who are underrepresented in these RCTs. This article is based on a meeting report authored by 12 scientists studying atrial fibrillation (AF) in diverse ways who discussed the management of challenging AF cases that are underrepresented in pivotal NOAC trials. METHODS: An advisory board panel was convened to confer on management strategies for challenging AF cases. The article is derived from a summary of case presentations and the collaborative discussions at the meeting. CONCLUSION: This expert consensus of cardiologists aimed to define management strategies for challenging cases with patients who underrepresented in pivotal trials using case examples from their routine practice. Although strong evidence is lacking, exploratory subgroup analysis of phase III pivotal trials partially informs the management of these patients. Clinical trials with higher external validity are needed to clarify areas of uncertainty. The lack of clear evidence about complex AF cases has pushed clinicians to manage patients based on clinical experience, including rare situations of off-label prescriptions
Targeting lyn kinase in chorea-acanthocytosis: A translational treatment approach in a rare disease
Background: Chorea-acanthocytosis (ChAc) is a neurodegenerative disease caused by mutations in the VPS13A gene. It is characterized by several neurological symptoms and the appearance of acanthocytes. Elevated tyrosine kinase Lyn activity has been recently identified as one of the key pathophysiological mechanisms in this disease, and therefore represents a promising drug target. Methods: We evaluated an individual off-label treatment with the tyrosine kinase inhibitor dasatinib (100 mg/d, 25.8–50.4 weeks) of three ChAc patients. Alongside thorough safety monitoring, we assessed motor and non-motor scales (e.g., MDS-UPDRS, UHDRS, quality of life) as well as routine and experimental laboratory parameters (e.g., serum neurofilament, Lyn kinase activity, actin cytoskeleton in red blood cells). Results: Dasatinib appeared to be reasonably safe. The clinical parameters remained stable without significant improvement or deterioration. Regain of deep tendon reflexes was observed in one patient. Creatine kinase, serum neurofilament levels, and acanthocyte count did not reveal consistent effects. However, a reduction of initially elevated Lyn kinase activity and accumulated autophagy markers, as well as a partial restoration of the actin cytoskeleton, was found in red blood cells. Conclusions: We report on the first treatment approach with disease-modifying intention in ChAc. The experimental parameters indicate target engagement in red blood cells, while clinical effects on the central nervous system could not be proven within a rather short treatment time. Limited knowledge on the natural history of ChAc and the lack of appropriate biomarkers remain major barriers for “clinical trial readiness”. We suggest a panel of outcome parameters for future clinical trials in ChA
Structure, Deformations and Gravitational Wave Emission of Magnetars
Neutron stars can have, in some phases of their life, extremely strong
magnetic fields, up to 10^15-10^16 G. These objects, named magnetars, could be
powerful sources of gravitational waves, since their magnetic field could
determine large deformations. We discuss the structure of the magnetic field of
magnetars, and the deformation induced by this field. Finally, we discuss the
perspective of detection of the gravitational waves emitted by these stars.Comment: 11 pages, 2 figures, prepared for 19th International Conference on
General Relativity and Gravitation (GR19), Mexico City, Mexico, July 5-9,
201
Cardiac tamponade from a giant thymoma: case report
Thymoma, the most common neoplasm of the anterior mediastinum especially in adults, accounts for 20-25% of all mediastinal tumors and 50% of anterior mediastinal masses. These tumors are routinely asymptomatic for prolonged periods of time. Pericardial tamponade is a very rare initial manifestation of a thymoma. This report presents a patient who had hemorrhagic pericardial tamponade that likely resulted from the largest symptomatic mixed type (type AB) thymoma described in the literature
Tkachenko waves, glitches and precession in neutron star
Here I discuss possible relations between free precession of neutron stars,
Tkachenko waves inside them and glitches. I note that the proposed precession
period of the isolated neutron star RX J0720.4-3125 (Haberl et al. 2006) is
consistent with the period of Tkachenko waves for the spin period 8.4s. Based
on a possible observation of a glitch in RX J0720.4-3125 (van Kerkwijk et al.
2007), I propose a simple model, in which long period precession is powered by
Tkachenko waves generated by a glitch. The period of free precession,
determined by a NS oblateness, should be equal to the standing Tkachenko wave
period for effective energy transfer from the standing wave to the precession
motion. A similar scenario can be applicable also in the case of the PSR
B1828-11.Comment: 6 pages, no figures, accepted to Ap&S
Lattice dynamics and structural stability of ordered Fe3Ni, Fe3Pd and Fe3Pt alloys
We investigate the binding surface along the Bain path and phonon dispersion
relations for the cubic phase of the ferromagnetic binary alloys Fe3X (X = Ni,
Pd, Pt) for L12 and DO22 ordered phases from first principles by means of
density functional theory. The phonon dispersion relations exhibit a softening
of the transverse acoustic mode at the M-point in the L12-phase in accordance
with experiments for ordered Fe3Pt. This instability can be associated with a
rotational movement of the Fe-atoms around the Ni-group element in the
neighboring layers and is accompanied by an extensive reconstruction of the
Fermi surface. In addition, we find an incomplete softening in [111] direction
which is strongest for Fe3 Ni. We conclude that besides the valence electron
density also the specific Fe-content and the masses of the alloying partners
should be considered as parameters for the design of Fe-based functional
magnetic materials.Comment: Revised version, accepted for publication in Physical Review
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