600 research outputs found
Probability weighting, stop-loss and the disposition effect
In this paper we study a continuous-time, optimal stopping model of an asset sale with prospect theory preferences under pre-commitment. We show for a wide range of value and probability weighting functions, including those of Tversky and Kahneman (1992), that the optimal prospect takes the form of a stop-loss threshold and a distribution over gains. It is skewed with a long right tail. This is consistent with both the widespread use of stop-loss strategies in financial markets, and recent experimental evidence. Moreover, our model with probability weighting in tandem with the S-shaped value function makes predictions for the disposition effect which match in magnitude that calculated by Odean (1998)
Electron-phonon relaxation and excited electron distribution in zinc oxide and anatase
We propose a first-principle method for evaluations of the time-dependent
electron distribution function of excited electrons in the conduction band of
semiconductors. The method takes into account the excitations of electrons by
external source and the relaxation to the bottom of conduction band via
electron-phonon coupling. The methods permits calculations of the
non-equilibrium electron distribution function, the quasi-stationary
distribution function with steady-in-time source of light, the time of setting
of the quasi-stationary distribution and the time of energy loss via relaxation
to the bottom of conduction band. The actual calculations have been performed
for titanium dioxide in the anatase structure and zinc oxide in the wurtzite
structure. We find that the quasi-stationary electron distribution function for
ZnO is a fermi-like curve that rises linearly with increasing excitation energy
whereas the analogous curve for anatase consists of a main peak and a shoulder.
The calculations demonstrate that the relaxation of excited electrons and the
setting of the quasi-stationary distribution occur within the time no more than
500 fsec for ZnO and 100 fsec for anatase.
We also discuss the applicability of the effective phonon model with
energy-independent electron-phonon transition probability. We find that the
model only reproduces the trends in changing of the characteristic times
whereas the precision of such calculations is not high. The rate of energy
transfer to phonons at the quasi-stationary electron distribution also have
been evaluated and the effect of this transfer on the photocatalyses has been
discussed. We found that for ZnO this rate is about 5 times less than in
anatase.Comment: 21 p., 9 figure
ANTINOCICEPTIVE PROPERTIES OF HYDRO ALCOHOLIC EXTRACTS OF ANETHUM GRAVEOLENS L. (DILL) SEED AND AERIAL PARTS IN MICE
Chronic pain and its treatment have always posed a significant challenge for medical practitioners and many
attempts have been made to reduce and eliminate it, both in past and recent history. Research to discover new
effective drugs with excellent safety profiles is ongoing. The aim of this study was to evaluate the suitability of the plant
Anethum graveolens (dill) for use as an analgesic drug.
Forty-two mice were divided randomly into seven groups (n=6). In the formalin test, the first group received normal
saline; the second group, extract of plant seed (300 mg/kg); the third group, extract of plant crops (300 mg/kg) and
the forth group received morphine (1 mg/kg). For the hot plate test, the first group received normal saline; the second
group, extract of plant seed (300 mg/kg) and the third group received extract of plant crops (300 mg/kg). All injections
consisted of 0.5 ml given intraperitoneally.
In the early phase of formalin test, the animals treated with seed and crop extracts did not show analgesic effects
compared to control group (P=0.386, P=0.284 respectively). In contrast, in the late phase of formalin test, seed and
crop extracts significantly decreased indications of pain compared to the saline group with seed extracts showing
stronger analgesic effects (P=0.004, P=0.023 respectively). In the hot plate test, crop and seed extracts showed
hyperalgesic properties. This effect was stronger in animals treated with crop extracts as compared to seed extracts.
These findings indicate that Anethum graveolens can reduce inflammatory pain, probably by inhibiting inflammatory
mediators. In contrast, this plant has no analgesic effects on spinal nociception and conversely may exacerbate it. This
study provides a basis for the use of Anethum graveolens extracts in popular folk medicine, but further studies are
necessary to elucidate the mechanism of its analgesic actions
A stochastic hybrid algorithm for multi-depot and multi-product routing problem with heterogeneous vehicles
Abstract. A mathematical model and heuristic method for solving multi-depot and multi-product vehicle routing problem (MD-MPVRP) with heterogeneous vehicles have been proposed in this article. Customers can order eclectic products and depots are supposed to deliver customers' orders before the lead time, using vehicles with diverse capacities, costs and velocities. Hence, mathematical model of multi-depot vehicle routing problem has been developed to mirror these conditions. This model is aimed at minimizing the serving distances which culminates in a reduction in prices and also serving time. As the problem is so complex and also solving would be too time-taking, a heuristic method has been offered. The heuristic method, at first, generates an initial solution through a three-step procedure which encompasses grouping, routing and vehicle selection, scheduling and packaging. Then it improves the solution by means of simulated annealing. We have considered the efficiency of offered algorithm by comparing its solutions with the optimum solutions and also during a case study. [V. Mahdavi Asl, S.A. Sadeghi, MR. Ostadali Makhmalbaf. A stochastic hybrid algorithm for multi-depot and multi-product routing problem with heterogeneous vehicles
Specific Image Characteristics Influence Attitudes about Chimpanzee Conservation and Use as Pets
Chimpanzees are endangered in their native Africa but in the United States, they are housed not only in zoos and research centers but owned privately as pets and performers. In 2008, survey data revealed that the public is less likely to think that chimpanzees are endangered compared to other great apes, and that this is likely the result of media misportrayals in movies, television and advertisements. Here, we use an experimental survey paradigm with composite images of chimpanzees to determine the effects of specific image characteristics. We found that those viewing a photograph of a chimpanzee with a human standing nearby were 35.5% more likely to consider wild populations to be stable/healthy compared to those seeing the exact same picture without a human. Likewise, the presence of a human in the photograph increases the likelihood that they consider chimpanzees as appealing as a pet. We also found that respondents seeing images in which chimpanzees are shown in typically human settings (such as an office space) were more likely to perceive wild populations as being stable and healthy compared to those seeing chimpanzees in other contexts. These findings shed light on the way that media portrayals of chimpanzees influence public attitudes about this important and endangered species
Coenzyme Q10 ameliorates trimethyltin chloride neurotoxicity in experimental model of injury in dentate gyrus of hippocampus: A histopathological and behavioral study
Background: Coenzyme Q10 has antioxidative and free radical scavenging effects. CoQ10 supplementation is known to have neuroprotective effects in some neurodegenerative diseases, such as Parkinson�s disease and Huntington�s disease. Objectives: The aim of this study was to evaluate both histopathologic and behavioral whether Coenzyme Q10 is protective against trimethyltin chloride (TMT) induced hippocampal damage. Materials and Methods: This was an experimental study. Thirty-six Balb/c mice were divided into four groups, as follows: 1) control group; 2) sham group of mice that received a 100 ±L intraperitoneal injection (IP) of sesame oil; 3) TMT group of mice that received a single 2.5 mg/kg/day IP injection of TMT; and 4) TMT + CoQ10 group of mice that received a 10 mg/kg IP injection of CoQ10. Body weight and Morris water maze (MWM) responses were investigated. In addition, the dentate gyrus neurons of the hippocampus were evaluated histopathologically by light and electron microscopes. Results: This study revealed that the body weight scale was found to be significantly higher in the CoQ10 group (21.39 ± 2.70), compared to the TMT group (19.39±2.74) (P < 0.05). In the TMT group, the animals showed body a weight loss that was significantly lower than that of the control group (22.33 ± 3.06) (P < 0.05). Our results showed that CoQ10 provided protection against MWM deficits. Furthermore, TMT impaired the ability of mice to locate the hidden platform, compared to the control group (P < 0.05). Microscopic studies showed that TMT caused histopathological changes in the dentate gyrus and increased the number of necrotic neurons (476±78.51), compared to the control group (208±40.84) (P < 0.001). But, CoQ10 significantly attenuated (31 9±60.08) the density of necrotic neurons compared to TMT (P < 0.05). Conclusions: The results of the present study indicate that Coenzyme Q10 diminished neuronal necrosis and improved learning memory. Part of its beneficial effect is due to its potential to discount oxidative stress. © 2016, Kowsar Medical Publishing Company. All rights reserved
Ferromagnetic interlayer coupling in CrSBr crystals irradiated by ions
Layered magnetic materials are becoming a major platform for future
spin-based applications. Particularly the air-stable van der Waals compound
CrSBr is attracting considerable interest due to its prominent
magneto-transport and magneto-optical properties. In this work, we observe a
transition from antiferromagnetic to ferromagnetic behavior in CrSBr crystals
exposed to high-energy, non-magnetic ions. Already at moderate fluences, ion
irradiation induces a remanent magnetization with hysteresis adapting to the
easy-axis anisotropy of the pristine magnetic order up to a critical
temperature of 110 K. Structure analysis of the irradiated crystals in
conjunction with density functional theory calculations suggest that the
displacement of constituent atoms due to collisions with ions and the formation
of interstitials favors ferromagnetic order between the layers
Mutation analysis of BRCA1 and BRCA2 genes in Iranian high risk breast cancer families
Background: Telomerase is a ribonucleoprotein enzyme that synthesises telomeres after cell
division and maintains chromosomal stability leading to cellular immortalization. Telomerase has
been associated with negative prognostic indicators in some studies. The present study aims to
detect any association between telomerase sub-units: hTERT and hTR and the prognostic
indicators including tumour's size and grade, nodal status and patient's age.
Methods: Tumour samples from 46 patients with primary invasive breast cancer and 3 patients
with benign tumours were collected. RT-PCR analysis was used for the detection of hTR, hTERT,
and PGM1 (as a housekeeping) genes expression.
Results: The expression of hTR and hTERT was found in 31(67.4%) and 38 (82.6%) samples
respectively. We observed a significant association between hTR gene expression and younger age
at diagnosis (p = 0.019) when comparing patients ≤ 40 years with those who are older than 40
years. None of the benign tumours expressed hTR gene. However, the expression of hTERT gene
was revealed in 2 samples.
No significant association between hTR and hTERT expression and tumour's grade, stage and nodal
status was seen.
Conclusion: The expression of hTR and hTERT seems to be independent of tumour's stage. hTR
expression probably plays a greater role in mammary tumourogenesis in younger women (≤ 40
years) and this may have therapeutic implications in the context of hTR targeting strategies
Strain-modulated defect engineering of two-dimensional materials
Strain- and defect-engineering are two powerful approaches to tailor the opto-electronic properties of two-dimensional (2D) materials, but the relationship between applied mechanical strain and behavior of defects in these systems remains elusive. Using first-principles calculations, we study the response to external strain of h-BN, graphene, MoSe2, and phosphorene, four archetypal 2D materials, which contain substitutional impurities. We find that the formation energy of the defect structures can either increase or decrease with bi-axial strain, tensile or compressive, depending on the atomic radius of the impurity atom, which can be larger or smaller than that of the host atom. Analysis of the strain maps indicates that this behavior is associated with the compressive or tensile local strains produced by the impurities that interfere with the external strain. We further show that the change in the defect formation energy is related to the change in elastic moduli of the 2D materials upon introduction of impurity, which can correspondingly increase or decrease. The discovered trends are consistent across all studied 2D materials and are likely to be general. Our findings open up opportunities for combined strain- and defect-engineering to tailor the opto-electronic properties of 2D materials, and specifically, the location and properties of single-photon emitters
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