807 research outputs found
КЛАССИФИКАЦИЯ МЕТОДОВ ПО УПРАВЛЕНИЮ ГЕОМЕХАНИЧЕСКИМИ ПРОЦЕССАМИ ПРИ ОСВОЕНИИ ПОДЗЕМНОГО ПРОСТРАНСТВА В СИРИИ В УСЛОВИЯХ НАБУХАЮЩЕГО ГРУНТОВО-ПОРОДНОГО МАССИВА
In the article defined the structure and classification of methods for management of geomechanical processes during the development of underground space in Syria in the conditions of swelling soil-rock mass. The different methods of protection of buildings and constructions which eliminate or reduce deformation of the bases of buildings and structures on swelling soil-rock masses.В статье определены структура и классификация методов по управлению геомеханическими процессами при освоении подземного пространства в Сирии в условиях набухающего грунтово-породного массива. Рассмотрены разные методы защиты зданий и сооружений, позволяющие устранить или уменьшать деформации оснований зданий и сооружений на набухающих грунтово-породных массивах
Various characteristics of Ni and Pt–Al2O3 nanocatalysts prepared by microwave method to be applied in some petrochemical processes
AbstractAlumina-supported metal nanocatalysts were prepared via the microwave method, by loading nano Ni particles (at 1, 3 and 5wt%) or nano Pt particles (at 0.3, 0.6 and 0.9wt%). Structural and adsorption features of the nano catalysts were revealed through XRD, DSC-DTA, TEM, H2-chemisorption and N2-physisorption. N2-adsorption–desorption isotherms of type IV were related typically to mesoporous materials with H2 class of hysteresis loops characterizing ink bottle type of pores. The well dispersed nano-sized metal particles were evidenced in the studied catalytic systems, exhibiting marked thermal stability up to 800°C. The catalytic performances of different catalyst samples were assessed during cyclohexane, normal hexane and ethanol conversions, using the micro-catalytic pulse technique at different operating conditions. The 5% Ni–γ–Al2O3 sample was found to be the most active in dehydration of ethanol to produce ethylene, as well as in n-hexane cracking. However, the 1% Ni–Al2O3 sample showed the highest dehydrogenation activity for selective production of benzene from cyclohexane. On the other hand, the 0.9% Pt–γ–Al2O3 sample exhibited the highest activity in the dehydration of ethanol and in the dehydrogenation of cyclohexane. The 0.3% Pt–γ–Al2O3 sample was the most active in the dehydrocyclization of normal hexane, as compared to the other catalyst samples under study
Ectoparasites of murids in peninsular Malaysia and their associated diseases
A considerable number of rat-borne ectoparasite studies have been conducted since the early 1930s in the Malayan Peninsula (now known as peninsular Malaysia). The majority of studies were field surveys and collections of specimens across the region, and were conducted primarily to catalogue the ectoparasite host distribution and discover novel species. This has generated a signification amount of information, particularly on the diversity and host distribution; other aspects such as morphology, host distribution and medical significance have also been investigated. Amongst the four main groups (mites, fleas, ticks, lice), rat-borne mites have received the most attention with a particular emphasis on chiggers, due to their medical importance. More recent studies have examined the distribution of ectoparasites in rats from different habitat type simplicating a high prevalence of zoonotic species infesting rat populations. Despite being capable of transmitting dangerous pathogens to human, the health risks of rat-borne ectoparasites appear to be small with no serious outbreaks of diseases recorded. Although an extensive number of works have been published, there remain gaps in knowledge that need to be addressed, such as, the distribution of under studied ectoparasite groups (listrophorids and myobiids), determining factors influencing infestation, and understanding changes to the population distribution over time
CP violation and CKM predictions from Discrete Torsion
We present a supersymmetric D-brane model that has CP spontaneously broken by
discrete torsion. The low energy physics is largely independent of the
compactification scheme and the kahler metric has `texture zeros' dictated by
the choice of discrete torsion. This motivates a simple ansatz for the kahler
metric which results in a CKM matrix given in terms of two free parameters,
hence we predict a single mixing angle and the CKM phase. The CKM phase is
predicted to be close to Pi/3.Comment: 21 pages, 8 figures, 1 Table. Significant modifications and
generalisation. Version to be publishe
Fully supersymmetric CP violations in the kaon system
We show that, on the contrary to the usual claims, fully supersymmetric CP
violations in the kaon system are possible through the gluino mediated flavor
changing interactions. Both and can be accommodated for relatively large without any
fine tunings or contradictions to the FCNC and EDM constraints.Comment: Contribution to the Proceedings of ICHEP2000, Osaka, 200
Spontaneous CP Violation in Non-Minimal Supersymmetric Models
We study the possibilities of spontaneous CP violation in the Next-to-Minimal
Supersymmetric Standard Model with an extra singlet tadpole term in the scalar
potential. We calculate the Higgs boson masses and couplings with radiative
corrections including dominant two loop terms. We show that it is possible to
satisfy the LEP constraints on the Higgs boson spectrum with non-trivial
spontaneous CP violating phases. We also show that these phases could account
for the observed value of epsilonK.Comment: 21 pages, 7 Figures in Encapsulated Postscrip
CP violation in supersymmetric model with non-degenerate A-terms
We study the CP phases of the soft supersymmetry breaking terms in
string-inspired models with non-universal trilinear couplings. We show that
such non-universality plays an important role on all CP violating processes. In
particular these new supersymmetric sources of CP violation may significantly
contribute to the observed CP phenomena in kaon physics while respecting the
severe bound on the electric dipole moment of the neutron.Comment: 14 pages, Late
Neutralino-Nucleon Cross Section and Charge and Colour Breaking Constraints
We compute the neutralino-nucleon cross section in several supersymmetric
scenarios, taking into account all kind of constraints. In particular, the
constraints that the absence of dangerous charge and colour breaking minima
imposes on the parameter space are studied in detail. In addition, the most
recent experimental constraints, such as the lower bound on the Higgs mass, the
branching ratio, and the muon are considered. The
astrophysical bounds on the dark matter density are also imposed on the
theoretical computation of the relic neutralino density, assuming thermal
production. This computation is relevant for the theoretical analysis of the
direct detection of dark matter in current experiments. We consider first the
supergravity scenario with universal soft terms and GUT scale. In this scenario
the charge and colour breaking constraints turn out to be quite important, and
\tan\beta\lsim 20 is forbidden. Larger values of can also be
forbidden, depending on the value of the trilinear parameter . Finally, we
study supergravity scenarios with an intermediate scale, and also with
non-universal scalar and gaugino masses where the cross section can be very
large.Comment: Final version to appear in JHE
Fermion Masses and Mixing in Intersecting Branes Scenarios
We study the structure of Yukawa couplings in intersecting D6-branes wrapping
a factorizable 6-torus compact space T^6. Models with MSSM-like spectrum are
analyzed and found to fail in predicting the quark mass spectrum because of the
way in which the family structure for the left-handed, right-handed quarks and,
eventually, the Higgses is `factorized' among the different tori. In order to
circumvent this, we present a model with three supersymmetric Higgs doublets
which satisfies the anomaly cancellation condition in a more natural way than
the previous models, where quarks were not treated universally regarding their
branes assignments, or some particular branes were singled out being invariant
under orientifold projection. In our model, the family structures for the left,
right quarks, left leptons and the Higgses arise from one of the tori and can
naturally lead to universal strength Yukawa couplings which accommodate the
quark mass hierarchy and the mixing angles.Comment: 21 pages, latex, matches the Phys. Rev. D versio
Spontaneous twin anemia polycythemia sequence: diagnosis, management, and outcome in an international cohort of 249 cases.
BACKGROUND: Twin anemia polycythemia sequence is a chronic form of unbalanced fetofetal transfusion through minuscule placental anastomoses in monochorionic twins, leading to anemia in the donor and polycythemia in the recipient. Owing to the low incidence of twin anemia polycythemia sequence, data on diagnosis, management, and outcome are limited. OBJECTIVE: This study aimed to investigate the diagnosis, management, and outcome in a large international cohort of spontaneous twin anemia polycythemia sequence. STUDY DESIGN: Data from the international twin anemia polycythemia sequence registry, retrospectively collected between 2014 and 2019, were used for this study. A total of 17 fetal therapy centers contributed to the data collection. The primary outcomes were perinatal mortality and severe neonatal morbidity. Secondary outcomes included a risk factor analysis for perinatal mortality and severe neonatal morbidity. RESULTS: A total of 249 cases of spontaneous twin anemia polycythemia sequence were included in this study, 219 (88%) of which were diagnosed antenatally and 30 (12%) postnatally. Twin anemia polycythemia sequence was diagnosed antenatally at a median gestational age of 23.7 weeks (interquartile range, 9.7-28.8; range, 15.1-35.3). Antenatal management included laser surgery in 39% (86 of 219), expectant management in 23% (51 of 219), delivery in 16% (34 of 219), intrauterine transfusion (with partial exchange transfusion) in 12% (26 of 219), selective feticide in 8% (18 of 219), and termination of pregnancy in 1% (3 of 219) of cases. Perinatal mortality rate was 15% (72 of 493) for the total group, 22% (54 of 243) for donors, and 7% (18 of 242) for recipients (P<.001). Severe neonatal morbidity occurred in 33% (141 of 432) of twins with twin anemia polycythemia sequence and was similar for donors (32%; 63 of 196) and recipients (33%; 75 of 228) (P=.628). Independent risk factors for spontaneous perinatal mortality were donor status (odds ratio, 3.8; 95% confidence interval, 1.9-7.5; P<.001), antenatal twin anemia polycythemia sequence stage (odds ratio, 6.3; 95% confidence interval, 1.4-27.8; P=.016 [stage 2]; odds ratio, 9.6; 95% confidence interval, 2.1-45.5; P=.005 [stage 3]; odds ratio, 20.9; 95% confidence interval, 3.0-146.4; P=.002 [stage 4]), and gestational age at birth (odds ratio, 0.8; 95% confidence interval, 0.7-0.9; P=.001). Independent risk factors for severe neonatal morbidity were antenatal twin anemia polycythemia sequence stage 4 (odds ratio, 7.9; 95% confidence interval, 1.4-43.3; P=.018) and gestational age at birth (odds ratio, 1.7; 95% confidence interval, 1.5-2.1, P<.001). CONCLUSION: Spontaneous twin anemia polycythemia sequence can develop at any time in pregnancy from the beginning of the second trimester to the end of the third trimester. Management for twin anemia polycythemia sequence varies considerably, with laser surgery being the most frequent intervention. Perinatal mortality and severe neonatal morbidity were high, the former especially so in the donor twins
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