An interacting scalar field and the recent cosmic acceleration

In this paper it is shown that the Brans - Dicke scalar field itself can serve the purpose of providing an early deceleration and a late time acceleration of the universe without any need of quintessence field if one considers an interaction, i.e, transfer of energy between the dark matter and the Brans - Dicke scalar field.Comment: 10 pages, 2 figure

Thermoelectric power of nondegenerate Kane semiconductors under the conditions of mutual electron-phonon drag in a high electric field

The thermoelectric power of nondegenerate Kane semiconductors with due regard for the electron and phonon heating, and their thermal and mutual drags is investigated. The electron spectrum is taken in the Kane two-band form. It is shown that the nonparabolicity of electron spectrum significantly influences the magnitude of the thermoelectric power and leads to a change of its sign and dependence on the heating electric field. The field dependence of the thermoelectric power is determined analytically under various drag conditions.Comment: 25 pages, RevTex formatted, 3 table

Thermal conductivity via magnetic excitations in spin-chain materials

We discuss the recent progress and the current status of experimental investigations of spin-mediated energy transport in spin-chain and spin-ladder materials with antiferromagnetic coupling. We briefly outline the central results of theoretical studies on the subject but focus mainly on recent experimental results that were obtained on materials which may be regarded as adequate physical realizations of the idealized theoretical model systems. Some open questions and unsettled issues are also addressed.Comment: 17 pages, 4 figure

Singularities in scalar-tensor gravity

The analysis of certain singularities in scalar-tensor gravity contained in a recent paper is completed, and situations are pointed out in which these singularities cannot occur.Comment: 6 pages, LaTe

Jamming at Zero Temperature and Zero Applied Stress: the Epitome of Disorder

We have studied how 2- and 3- dimensional systems made up of particles interacting with finite range, repulsive potentials jam (i.e., develop a yield stress in a disordered state) at zero temperature and applied stress. For each configuration, there is a unique jamming threshold, $\phi_c$, at which particles can no longer avoid each other and the bulk and shear moduli simultaneously become non-zero. The distribution of $\phi_c$ values becomes narrower as the system size increases, so that essentially all configurations jam at the same $\phi$ in the thermodynamic limit. This packing fraction corresponds to the previously measured value for random close-packing. In fact, our results provide a well-defined meaning for "random close-packing" in terms of the fraction of all phase space with inherent structures that jam. The jamming threshold, Point J, occurring at zero temperature and applied stress and at the random close-packing density, has properties reminiscent of an ordinary critical point. As Point J is approached from higher packing fractions, power-law scaling is found for many quantities. Moreover, near Point J, certain quantities no longer self-average, suggesting the existence of a length scale that diverges at J. However, Point J also differs from an ordinary critical point: the scaling exponents do not depend on dimension but do depend on the interparticle potential. Finally, as Point J is approached from high packing fractions, the density of vibrational states develops a large excess of low-frequency modes. All of these results suggest that Point J may control behavior in its vicinity-perhaps even at the glass transition.Comment: 21 pages, 20 figure

Observational Consequences of Evolution of Primordial Fluctuations in Scalar-Tensor Cosmology

Evolution of primordial fluctuations in a Brans-Dicke type scalar-tensor gravity theory is comprehensively investigated. The harmonic attractor model, in which the scalar field has its harmonic effective potential in the Einstein conformal frame and the theory relaxes toward Einstein gravity with time, is considered. The evolution of adiabatic initial perturbations in flat SCDM models is examined from the radiation-dominated epoch up to the present. We discuss how the scalar-tensor gravity affects the evolution of metric and matter perturbations, mainly focusing on the observational consequences, i.e., the matter power spectrum and the power spectrum of cosmic microwave background temperature. We find that the early time deviation is characterized only by the large static gravitational constant while the late time behavior is qualitatively different from that in Einstein gravity because the time variation of the gravitational constant and its fluctuation have non-negligible effects. The attracting scalar-tensor gravity affects only small scale modes due to its attracting nature, the degree of which is far beyond the post-Newtonian deviation at the present epoch.Comment: 18 page

Современные подходы к морфологической диагностике нейроэндокринных опухолей поджелудочной железы и прогнозированию их клинического течения на основе анализа собственной базы данных

Aim: Combined clinical and morphological analysis of the pancreatic neuroendocrine tumor (pNET) spectrum according to the new World Health Organization classification: patient distribution, hormonal status, morphological grading, somatostatin receptor 2 (SSR2) and 5 (SSR5) expression, the choice of tissue-specific markers for the differential diagnosis of primary NET in the pancreas based on metastases with unknown primary tumor.Materials and methods: The study was performed with 472 tissue samples from pNETs taken from patients. Morphological analysis consisted of histological and immunohistochemical examination with a panel of antibodies to chromogranin A, synaptophysin, CD56, insulin, glucagon, somatostatin, gastrin, calcitonin, adrenocorticotropic hormone (ACTH), serotonin, pancreatic polypeptide, cytokeratins (CK) of a wide spectrum, CK7 and CK19, p53, Ki-67, SSR 2 and SSR5, PDX-1, Isl-1, and NESP-55.Results: In women, the prevalence of pNETS was 2.3 higher than in men (2.3:1). We were able to identify 299 (63.3%) insulinomas, 134 (28.4%) non-functioning NETs, 28 (5.9%) gastrinomas and 1.8% rare tumors (somatostatinomas, “calcitoninomas” and ACTH-producing). Metastatic tumors were found in 16.5% of the cases. Multiple endocrine neoplasia syndrome type 1 was confirmed in 11.9% of the pNET patients, and in 30.8% of those aged below 30 years. Multiple tumors (2 to 10) were found in 32 patients by the time of the diagnosis or occurred at 7 to 18 years after initial surgery. 28.3% of the tumors were CK19-positive, with 54.4% of them being metastatic. Insulinomas were least prone to metastasizing (5.7% of the cases), with 41.2% of them being CK19-positive. Metastases were found in 70.4, 66.7, 100, and 100% of gastrinomas, “calcitoninomas”, ACTH-producing, and somatostatinomas, respectively, with CK19-positivity found in 85.2, 66.7, 66.7, and 100% of these tumors. SSR2 expression was observed in all gastrinomas and “calcitoninomas”, in 90.5% of “glucagonomas”, 85.7% of PPomas, and 66.7% of somatostatinomas. SSR5 expression was significantly less frequent. 86.3% of the studied tumors were PDX-1-positive: all somatostatinomas, 97.4% of insulinomas, 92.3% of gastrinomas, 83.3% of PPomas, 80% of the non-functioning NETs. PDX-1-negativity was identified in all “calcitoninomas” and in 57.1% of the non-functioning “glucagonomas”. 83.3% and 90.9% of the pNETs were Isl-1 and NESP-55-positive, respectively.Conclusion: Combined morphological and immunohistochemical examination of pNETs allows for the correct diagnosis, assessment of their prognosis and choice of the most effective treatment. The malignancy grade of pNETs depends on the cell immunophenotype and is higher in the cases with co-expression of the markers of neuroendocrine and ductal differentiation (CK19), as well as with ectopic hormonal production.Цель – комплексный клинико-морфологический анализ спектра нейроэндокринных опухолей (НЭО) поджелудочной железы (ПЖ) согласно новой классификации Всемирной организации здравоохранения (2017): состав пациентов, гормональный статус, морфологические критерии злокачественности, экспрессия рецепторов к соматостатину 2 (ССР 2) и 5-го типов (ССР 5), выбор тканеспецифических маркеров для дифференциальной диагностики первичной локализации НЭО в ПЖ по метастазам без известного первичного очага.Материал и методы. Материалом исследования послужили 472 образца ткани НЭО ПЖ от пациентов. Морфологический анализ включал гистологический и иммуногистохимический методы исследования со спектром антител к хромогранину А, синаптофизину, CD56, инсулину, глюкагону, соматостатину, гастрину, кальцитонину, адренокортикотропному гормону (АКТГ), серотонину, панкреатическому полипептиду, цитокератинам (ЦК) широкого спектра, ЦК 7 и 19, p53, Ki-67, ССР 2 и ССР 5, PDX-1, Isl-1, NESP55.Результаты. НЭО ПЖ встречались у женщин в 2,3 раза чаще, чем у мужчин (2,3:1). Были верифицированы 299 (63,3%) инсулином, 134 (28,4%) нефункционирующих НЭО, 28 (5,9%) гастрином и 1,8% редких опухолей (соматостатином, «кальцитонином» и АКТГ-продуцирующих). Метастазы были выявлены в 16,5% случаев. Синдром множественных эндокринных неоплазий 1-го типа был подтвержден у 11,9% пациентов с НЭО ПЖ, а у пациентов в возрасте до 30 лет – в 30,8% случаев. Множественные опухоли (от 2 до 10) у 32 пациентов были на момент установления диагноза или возникали через 7–18 лет после операции. ЦК19-позитивными были 28,3% опухолей, из них 54,4% с метастазами. Реже всего (в 5,7% случаев) метастазы были при инсулиномах, из них 41,2% были ЦК19-позитивными. Метастазы в гастриномах, «кальцитониномах», АКТГ-продуцирующих опухолях, соматостатиномах встречались в 70,4, 66,7, 100 и 100% случаев, ЦК19-позитивными были 85,2, 66,7, 66,7 и 100% опухолей соответственно. Экспрессия ССР 2 наблюдалась во всех гастриномах и «кальцитониномах», в 90,5% «глюкагоном», 85,7% «пипом», 66,7% соматостатином; экспрессия ССР 5 отмечена значительно реже. PDX-1-позитивными были 86,3% исследованных опухолей, все (100%) соматостатиномы, 97,4% инсулином, 92,3% гастрином, 83,3% «пипом», 80% нефункционирующих НЭО, PDX-1негативными – все (100%) «кальцитониномы» и 57,1% нефункционирующих «глюкагоном». Isl-1 и NESP-55-позитивными были 83,3 и 90,9% НЭО ПЖ.Заключение. Комплексное морфологическое и иммуногистохимическое исследование НЭО ПЖ позволяет правильно поставить диагноз, оценить прогноз и выбрать наиболее эффективное лечение. Злокачественный потенциал НЭО ПЖ зависит от иммунофенотипа клеток, он выше при ко-экспрессии маркеров нейроэндокринной и протоковой дифференцировки (ЦК19) и при продукции эктопических гормонов