12 research outputs found
Short view of leukemia diagnosis and treatment in Iran
Background: Early diagnosis and treatment of leukemia patients remains a fundamental aim in clinical oncology, especially in developing country. Present study highlights the basic requirements of these patients in Iran. Better understanding of these issues may lead to improve the healthcare standards toward leukemia diagnosis and treatment. Methods: This descriptive study included 101 specialists in hematology-oncology and pathology serving in oncology centers. The participants were then asked to fill out a standard questionnaire on the issues around diagnosis and treatment of blood malignancies. Results: According to specialists, unfair distribution of facilities across the country, delayed diagnosis of disease, absence of psychological support for patients, and insufficient financial support were the main reasons of inappropriate diagnosis and treatment in leukemia patients. Conclusions: Our results show that making an amendment to health policies by preparing well-equipped medical centers in all provinces, improving the morale of patients through consultation during the process of treatment, and above all, subsiding leukemia patients' financial problems will promote the health standard regarding the leukemia diagnosis and treatment in Iran. © 2015, Tehran University of Medical Sciences (TUMS). All rights reserved
Inflation and late time acceleration in braneworld cosmological models with varying brane tension
Braneworld models with variable brane tension introduce a new
degree of freedom that allows for evolving gravitational and cosmological
constants, the latter being a natural candidate for dark energy. We consider a
thermodynamic interpretation of the varying brane tension models, by showing
that the field equations with variable can be interpreted as
describing matter creation in a cosmological framework. The particle creation
rate is determined by the variation rate of the brane tension, as well as by
the brane-bulk energy-matter transfer rate. We investigate the effect of a
variable brane tension on the cosmological evolution of the Universe, in the
framework of a particular model in which the brane tension is an exponentially
dependent function of the scale factor. The resulting cosmology shows the
presence of an initial inflationary expansion, followed by a decelerating
phase, and by a smooth transition towards a late accelerated de Sitter type
expansion. The varying brane tension is also responsible for the generation of
the matter in the Universe (reheating period). The physical constraints on the
model parameters, resulted from the observational cosmological data, are also
investigated.Comment: 25 pages, 8 figures, accepted for publication in European Physical
Journal
CDM, DGP and extended phantom-like cosmologies
In this paper we compare outcomes of some extended phantom-like cosmologies
with each other and also with CDM\, and DGP. We focus on the
variation of the luminosity distances, the age of the universe and the
deceleration parameter versus the redshift in these scenarios. In a dynamical
system approach, we show that the accelerating phase of the universe in the
-DGP scenario is stable if one consider the \emph{curvature fluid} as a
phantom scalar field in the equivalent scalar-tensor theory, otherwise it is a
transient and unstable phenomenon. Up to the parameters values adopted in this
paper, the extended -DGP scenario is closer to the CDM
scenario than other proposed models. All of these scenarios explain the
late-time cosmic speed-up in their normal DGP branches, but the redshift at
which transition to the accelerating phase occurs are different: while the
DGP model transits to the accelerating phase much earlier, the
-DGP model transits to this phase much later than other scenarios.
Also, within the parameter spaces adopted in this paper, the age of the
universe in the -DGP model is larger than CDM, but this age in
-DGP is smaller than CDM.Comment: 37 pages, 6 figures, accepted for publication in Astrophyics and
Space Scienc
A Braneworld Dark Energy Model with Induced Gravity and the Gauss-Bonnet Effect
We construct a holographic dark energy model with a non-minimally coupled
scalar field on the brane where Gauss-Bonnet and Induced Gravity effects are
taken into account. This model provides a wide parameter space with several
interesting cosmological implications. Especially, the equation of state
parameter of the model crosses the phantom divide line and it is possible to
realize bouncing solutions in this setup.Comment: 20 pages, 3 eps figures, to appear in IJT
Stochastic stabilization of slender beams in space: Modeling and boundary control
This paper considers the problem of modeling and boundary feedback stabilization of extensible and shearable slender beams with large deformations and large rotations in space under both deterministic and stochastic loads induced by flows. Fully nonlinear equations of motion of the beams are first derived. Boundary feedback controllers are then designed for global practical exponential p-stabilization of the beams based on the Lyapunov direct method. A new Lyapunov-type theorem is developed to study well-posedness and stability of stochastic evolution systems (SESs) in Hilbert space
Hurricane Harvey Report: A fact-finding effort in the direct aftermath of Hurricane Harvey in the Greater Houston Region
On August 25, 2017, Hurricane Harvey made landfall near Rockport, Texas as a Category 4 hurricane with maximum sustained winds of approximately 200 km/hour. Harvey caused severe damages in coastal Texas due to extreme winds and storm surge, but will go down in history for record-setting rainfall totals and flood-related damages. Across large portions of southeast Texas, rainfall totals during the six-day period between August 25 and 31, 2017 were amongst the highest ever recorded, causing flooding at an unprecedented scale. More than 100,000 residential properties are estimated to have been affected in southeast Texas. It is likely that Harvey will rank among the costliest storms in U.S. history.In the wake of Hurricane Harvey, Delft University of Technology has initiated a Harvey Research Team to undertake a coordinated multidisciplinary investigation of the events with a focus on the greater Houston area. This ‘fact-finding’ research is based on information available from public sources during and in the first weeks after the event. Results are therefore preliminary, but aim to provide insight into lessons that can be learned for both Texas and the Netherlands. As part of the investigations, a hackathon with more than 80 participants was organized to collect and analyze available public information.Houston was especially hard hit by flooding. During the event, all 22 watersheds in the greater Houston area experienced flooding. Many of Houston’s creeks and bayous exceeded their channel capacities, reaching water levels never before recorded. Across large portions of Harris County, rainfall totals exceeded the 1000-year return period. In addition, the water from the two reservoirs protecting downtown Houston (Addicks and Barker) were opened on August 28 to prevent catastrophic damages to the dams and further flooding in upstream communities. The releases exacerbated flooding in the areas downstream of the dams and an estimated 4,000 homes in neighborhoods downstream of the dams were impacted by flooding. The consequences of the event in the greater Houston area have been characterized in terms of economic damages, loss of life and impacts on critical infrastructure, airports and industry. In total, more than 100,000 homes were affected more than 70 fatalities were reported in the greater Houston area. The event highlighted the vulnerability of industrial facilities, as several cascading impacts (releases of toxic materials and explosions) were reported. Emergency response has been assessed. No large-scale mandatory evacuation was ordered before or during Harvey. However, it appeared that several local evacuations were ordered for areas with specific risks and circumstances. During the event, many people were trapped by rising waters necessitating a major rescue operation. In total, more than 10,000 rescues were made by professional and volunteer rescuers. Social media played an important role during the event and recovery, as an additional source of information, to inform emergency managers and as a means to organize community response e.g. for clean-up. Also, messages were conveyed through social media, e.g. a report of a levee breach that appeared to be incorrect afterwards.Major flooding is a problem that has multiple causes from both physical and social origin. Based on the investigations, recommendations for future research and lessons for flood management have been formulated. A better understanding of the issues studied in this report is expected to contribute to a knowledge basis for further in-depth investigations and future directions for flood risk reduction.Data collection and Report production funded by DIMI and DSysSpecial Case 'Houston Galveston Bay Region, Texas, USA'Project 'Harvey hackathon' and follow-up researchHydraulic Structures and Flood RiskPolicy AnalysisIntegral Design and ManagementSafety and Security ScienceSystem EngineeringMathematical Geodesy and Positionin
Study of a spherical Xenon gas TPC for neutrinoless double beta detection
Several efforts are ongoing for the development of spherical gaseous time projection chamber detectors for the observation of rare phenomena such as weakly interacting massive particles or neutrino interactions. The proposed detector, thanks to its simplicity, low energy threshold and energy resolution, could be used to observe the ββ0ν process i.e. the neutrinoless double beta decay. In this work, a specific setup is presented for the measurement of ββ0ν on 50 kg of 136Xe. The different backgrounds are studied, demonstrating the possibility to reach a total background per year in the detector mass at the level of 2 events per year. The obtained results are competitive with the present generation of experiments and could represent the first step of a more ambitious roadmap including the ββ0ν search with different gases with the same detector and therefore the same background sources. The constraints in terms of detector constructions and material purity are also addressed, showing that none of them represents a show stopper for the proposed experimental setup