379 research outputs found
Effect of anisotropy on the field induced quantum critical properties of the three dimensional s=1/2 Heisenberg model
The field induced quantum critical properties of the three dimensional
spin-1/2 anisotropic antiferromagnetic Heisenberg model has been studied. We
have investigated the quantum phase transition between the spiral order and
field induced ferromagnetic order by means of Bose-Einstein condensation of
magnons in terms of a bosonic representation. The effect of in-plane anisotropy
on the critical properties has been studied via the bosonic model by Green's
function approach. We have found an analytic expression for the gap exponent in
addition to numerical results for the critical magnetic field in terms of
anisotropy parameter. The in-plane anisotropy breaks the U(1) symmetry
explicitly which changes the universal behavior by a drastic change on the gap
exponent. Moreover, the critical magnetic field depends strongly on the
in-plane anisotropies. The divergence of the transverse structure factor at the
antiferromagnetic wave vector confirms the onset of the magnetic order which
scales with the negative value of gap exponent as the magnetic field approaches
the critical one. The transverse staggered magnetization as an order parameter
vanishes with exponent when the magnetic field reaches its critical
value in low field region.Comment: 9 pages and 2 figure
Machine Learning-Based Estimation of Soil’s True Air-Entry Value from GSD Curves
The application of machine learning (ML) methods has proven to be promising in dealing with a wide range of geotechnical engineering problems in recent years. ML methods have already been used for the prediction of soil water retention curves (SWRC) and estimation of air-entry values (AEV). However, the reported works in the literature are generally based on limited data and conventional, less accurate approaches for AEV estimation. In this paper, a large database, known as UNsaturated SOil hydraulic DAtabase (UNSODA), is studied and the conventional and true AEVs of 790 soil samples are estimated based on determination methods reported in the literature. A ML approach is then employed for the development of a predictive model for the estimation of true AEV from water content-based SWRCs of a wide range of soil types taking into account the impact of bulk density and grain size distribution parameters. The obtained results reveal an enhanced accuracy in AEV determination, featuring R2 values of 0.964, 0.901 and 0.851 for training, validation, and testing data, respectively, which confirm the marked performance of the developed ML model. Based on the results of a sensitivity analysis, the particle sizes of 50 and 250 µm are found to have the highest impact on the AEV estimation
Mycoplasma genitalium and cancer: A brief review
Approximately, 15-20 of all cancers worldwide are caused by infectious agents. Understanding the role of infectious agents on cancer development might be useful for developing new approaches to its prevention. Mycoplasma genitalium is a clinically important sexually transmitted pathogen that has been associated with several human diseases. There have been a few studies suggestive of probable roles of Mycoplasma genitalium in cancer development, including prostate and ovarian cancers and lymphomas, but the role of this microorganism like other Mycoplasma species in neoplasia is still conjectural. Considering the prevalence of Mycoplasma genitalium infections and also the emergence of resistant strains, Mycoplasma genitalium needs more attention in the infectious agent cancer-causing research area
Kinetic Theory of Collisionless Self-Gravitating Gases: Post-Newtonian Polytropes
In this paper we study the kinetic theory of many-particle astrophysical
systems and we present a consistent version of the collisionless Boltzmann
equation in the 1PN approximation. We argue that the equation presented by
Rezania and Sobouti in A&A 354 1110 (2000) is not the correct expression to
describe the evolution of a collisionless self-gravitating gas. One of the
reasons that account for the previous statement is that the energy of a
free-falling test particle, obeying the 1PN equations of motion for static
gravitational fields, is not a static solution of the mentioned equation. The
same statement holds for the angular momentum, in the case of spherical
systems. We provide the necessary corrections and obtain an equation that is
consistent with the corresponding equations of motion and the 1PN conserved
quantities. We suggest some potential relevance for the study of high density
astrophysical systems and as an application we construct the corrected version
of the post-Newtonian polytropes.Comment: 23 pages, 24 figures. Accepted for publication in PR
Green's function approach to quantum criticality in the anisotropic Kondo-necklace model
We have studied the quantum phase transition between the antiferromagnetic
and spin liquid phase for the two dimensional anisotropic Kondo-necklace model.
The bond operator formalism has been implemented to transform the spin
Hamiltonian to a bosonic one. We have used the Green's function approach
including a hard core repulsion to find the low energy excitation spectrum of
the model. The bosonic excitations become gapless at the quantum critical point
where the phase transition from the Kondo singlet state to long range
antiferromagnetic order takes place. We have studied the effect of both
inter-site (delta) and local (Delta) anisotropies on the critical point and on
the critical exponent of the excitation gap in the paramagnetic phase. We have
also compared our results with previous bond operator mean field calculations.Comment: 14 pages and 7 EPS figure
Beban Kerja Fisik dan Lama Kerja Terhadap Keluhan Musculoskeletal Pada Pekerja Bengkel Las di Wilayah Kusumodilagan Surakarta
Introduction: One of the businesses that has a very high level of risk of complaints regarding health is in the informal sector, this is because the implementation of OSH is still not implemented properly. This study aims to determine the relationship between length of work and physical workload with musculoskeletal complaints in welding shop workers in the Kusumodilagan area, Surakarta. Methods: This type of research is quantitative with a cross-sectional approach. The research sample is 44 respondents. The sampling technique uses total sampling. Collecting data by interview using a questionnaire. The statistical test uses the Rank Spearman test. Results: the results showed that there was no relationship between length of work and musculoskeletal complaints (p value 0.411 > 0.005) and there was a relationship between physical workload and musculoskeletal complaints (p value 0.001 <0.005). Conclusion: Can affect the occurrence of musculoskeletal complaints in welding workshop workers.Adjusting the physical workload received by workers is one of the efforts that can be made to reduce the level of musculoskeletal complaints that occur
Large frequency drifts during Type I X-ray bursts
We study the spin-down of a neutron star atmosphere during the Type I X-ray
burst in low mass X-ray binaries. Using polar cap acceleration models, we show
that the resulting stellar ``wind'' torque on the burning shell due to the
flowing charged particles (electrons, protons and ions) from the star's polar
caps may change the shell's angular momentum during the burst. We conclude that
the net change in the angular momentum of the star's atmosphere can account for
rather large frequency drifts observed during Type I X-ray burst.Comment: 8 pages, more discussion adde
Removal of polycyclic aromatic hydrocarbons (PAHs) by different physicochemical methods: A mini-review
PAHs are persistent organic pollutants spread worldwide in our environment, including air, soil, and water. They are a large class of organic pollutants released mainly from anthropogenic sources, including automobiles and incomplete combustion of fossil fuels, power plants, and natural sources like forest fires and volcanic eruptions. In recent years, a variety of treatment methods have been used to degrade PAHs in the environment. This paper reviewed the most frequent physicochemical methods for PAHs removal, including solvent extraction/soil washing, oxidation, ozone, solidification, and supercritical fluid extraction. The findings showed that combining physicochemical methods can be an effective option for better cleanup of PAH from contaminated areas
Analyzing utilization of biomass in combined heat and power and combined cooling, heating, and power systems
Nowadays, ever-increasing energy demands and the depletion of fossil fuels require efficient and environmentally friendly technologies for energy generation. In this context, energy systems integration makes for a very strong proposition since it results in energy saving, fuel diversification, and the supply of cleaner energy. To this end, it is of the utmost importance to realize the current developments in this field and portray the state of the art of renewable generation in integrated energy systems. This review evaluates the utilization of bioenergy in cogeneration and trigeneration systems. The statistical reports of bioenergy and combined heat and power deployments in 28 countries of the European Union are discussed. Then, the most common research objectives of biomass-fueled combined heat and power systems are classified into three primary performance analyses, namely, energy and exergy analysis, thermo-economic optimization, and environment assessment. The influencing parameters of biomass utilization on each type of assessment are discussed, and the basic principles for carrying out such analyses in energy systems are explained. It is illustrated that the properties of feedstock, selection of appropriate conversion technology, associated costs with the biomass-to-bioenergy process, and sustainability of biomass are the primary influencing factors that could significantly affect the results of each assessment
Vitamin D3 Controls TLR4- A nd TLR2-Mediated Inflammatory Responses of Endometrial Cells
Objectives: Vitamin D has potent immunoregulatory features and modulates innate and adaptive immune responses. There is a significant association between intrauterine infection-associated inflammatory responses and pregnancy complications such as abortion and preterm labor. Here, we investigated how 1,25 (OH)2 D3 could modulate inflammatory responses of endometrial cells. Design: This is an in vitro experimental study. Endometrial stromal cells (ESCs) and whole endometrial cells (WECs) were collected from 15 apparently normal women, and the immunomodulatory effects of 1,25 (OH)2 D3 on lipopolysaccharide (LPS)-or lipoteichoic acid (LTA)-treated ESCs and WECs were investigated. Participants/Materials, Setting, and Methods: Women with no history of abortion, infertility, endometriosis, or sign of vaginal infection were enrolled in this study. Endometrial samples were collected by gynecologists using a Pipelle pipette in the proliferative phase of the menstrual cycle. WECs and ESCs were collected and treated with either LPS or LTA. The levels of IL-6, IL-8, and TNF-α in culture supernatants were quantified using the ELISA technique. TLR2, TLR4, and MyD88 expressions were assessed by RT-qPCR. TLR4 expression at the protein level was studied by the Western blot technique. Results: 1,25 Dihydroxycholecalciferol (1,25 (OH)2 D3) significantly reduced TNF-α production in LPS-activated ESCs and TNF-α and IL-6 production by LTA-stimulated WECs. In contrast, 1,25 (OH)2 D3 pretreatment increased the production of IL-8 by LPS- A nd LTA-stimulated endometrial cells. 1,25 (OH)2 D3 pretreatment markedly reduced LPS-induced TLR4 protein expression by ESCs. LPS treatment of ESCs significantly induced MyD88 gene expression. This effect was reversed when these cells were pretreated with 1,25 (OH)2 D3 before stimulation with LPS. Limitations: Because of the small size of samples, doing experiments all together on some samples was not feasible. Confirmation of the results obtained here needs well-designed in vivo studies. Conclusions: 1,25 (OH)2 D3 is an immunomodulatory molecule essential for maintaining endometrial immune homeostasis by controlling potentially harmful inflammatory responses associated with female reproductive tract infections. © 202
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