Thermal Equilibration of 176-Lu via K-Mixing

In astrophysical environments, the long-lived (\T_1/2 = 37.6 Gy) ground state of 176-Lu can communicate with a short-lived (T_1/2 = 3.664 h) isomeric level through thermal excitations. Thus, the lifetime of 176-Lu in an astrophysical environment can be quite different than in the laboratory. We examine the possibility that the rate of equilibration can be enhanced via K-mixing of two levels near E_x = 725 keV and estimate the relevant gamma-decay rates. We use this result to illustrate the effect of K-mixing on the effective stellar half-life. We also present a network calculation that includes the equilibrating transitions allowed by K-mixing. Even a small amount of K-mixing will ensure that 176-Lu reaches at least a quasi-equilibrium during an s-process triggered by the 22-Ne neutron source.Comment: 9 pages, 6 figure

Stretching short biopolymers by fields and forces

We study the mechanical properties of semiflexible polymers when the contour length of the polymer is comparable to its persistence length. We compute the exact average end-to-end distance and shape of the polymer for different boundary conditions, and show that boundary effects can lead to significant deviations from the well-known long-polymer results. We also consider the case of stretching a uniformly charged biopolymer by an electric field, for which we compute the average extension and the average shape, which is shown to be trumpetlike. Our results also apply to long biopolymers when thermal fluctuations have been smoothed out by a large applied field or force.Comment: 10 pages, 7 figure

Monte-Carlo study of scaling exponents of rough surfaces and correlated percolation

We calculate the scaling exponents of the two-dimensional correlated percolation cluster's hull and unscreened perimeter. Correlations are introduced through an underlying correlated random potential, which is used to define the state of bonds of a two-dimensional bond percolation model. Monte-Carlo simulations are run and the values of the scaling exponents are determined as functions of the Hurst exponent H in the range -0.75 <= H <= 1. The results confirm the conjectures of earlier studies

Zero-Temperature Phase Transitions of Antiferromagnetic Ising Model of General Spin on a Triangular Lattice

We map the ground-state ensemble of antiferromagnetic Ising model of spin-S on a triangular lattice to an interface model whose entropic fluctuations are proposed to be described by an effective Gaussian free energy, which enables us to calculate the critical exponents of various operators in terms of the stiffness constant of the interface. Monte Carlo simulations for the ground-state ensemble utilizing this interfacial representation are performed to study both the dynamical and the static properties of the model. This method yields more accurate numerical results for the critical exponents. By varying the spin magnitude in the model, we find that the model exhibits three phases with a Kosterlitz-Thouless phase transition at 3/2<S_{KT}<2 and a locking phase transition at 5/2 < S_L \leq 3. The phase diagram at finite temperatures is also discussed.Comment: 15 pages, LaTeX; 10 figures in PostScript files; The revised version appears in PRB (see Journal-ref). New electronic address of first author, [email protected]

Historical origin and meaning of the term „glial tumor“

In everyday neurosurgical practice, the term „glial tumor“ is associated with astrocytomas, glioblastomas, and oligodendrogliomas, although historically this has not always been the case. The term „glial tumor“ was first given by Virchow in the 19th century as a term initially combining all primary brain tumors under this name. It derives from the name of the group of „supporting“ nerve cells - glia or neuroglia (from the Greek glia - glue), a group which for many years was wrongly ascribed only a cohesive or supporting function.In 1926, in their classification of glial tumors - A Classification of the Tumors of the Glioma Group on a Histogenetic Basis with a Correlated Study of Prognosis, one of the founding fathers of neuropathology Percival Bailey and the founding father of modern neurosurgery – Harvey Cushing ascribed several different tumors in this group: in addition to neuroepithelioma, spongioblastoma multiforme, astrocytoma and ependymoma, they also add medulloblastoma, astroblastoma, oligodendroglioma and unipolar spongioblastoma. Since then, the classification of glial tumors has undergone many changes to its current form. In the latest classification of brain tumors published in 2021, glial tumors are united in a common group together with glioneuronal and neuronal tumors. Their extensive group includes tumors with different prognosis, age presentation, molecular profile and therapeutic response. From a neurosurgical point of view, the term „glial tumor“ does not carry a prognostic value, but only determines the belonging of the tumor to the astrocyte, oligodendrocyte cell line or their precursor cells. In relation to that an interesting question arises- why the remaining tumors originating from glial cells other than astrocytic, such as ependymomas, lost their belonging to the group of glial tumors, or such as intracranial schwannomas, are not included in it at all

Methods of cognitive status research in patients with glioblastoma

Introduction: Glioblastoma is a high-grade, aggressive central nervous system tumor with predominantly astrocytic differentiation, characterized by fast invasive growth into the surrounding brain parenchyma and aggressive clinical course. The short life expectancy of patients diagnosed with glioblastoma necessitates the need to maximize their quality of remaining life. One of the most common reasons for quality of life impairment in these patients is the cognitive deficit accompanying the disease. There is a lack of a unified and standardized method for the assessment of cognitive functions in these patients, which meets all the necessary criteria to be convenient and usable in the wide clinical practice.Aim: The aim of the present study is to compare the Montreal cognitive assessment (MoCA) brief screening test with an extended neuropsychological examination to determine its applicability in patients diagnosed with glioblastoma. Material and methods: The study includes 27 patients undergoing neurosurgical intervention for histologically proven IDH-wildtype glioblastoma in the Department of Neurosurgery, “St. Marina” University Hospital – a tertiary healthcare center, for the period January 2019 to December 2022. Preoperatively, patients were examined with the short MoCA screening test and an extended neuropsychological examination including the following subtests: Issac set test, Trail making test A and B, Luria test, Raven‘s color matrices, Stroop test and Bender test.Results: Of all the patients studied, those with a MoCA score below 26 points present at least one negative test of the extended neuropsychological examination. MoCA patients with scores of 26 or more do not demonstrate cognitive impairment in the extended neuropsychological impairment.Conclusion: The obtained results support the claim that the MoCA short screening test is applicable for preoperative diagnosis of cognitive disorders in patients with glioblastoma. Due to the study‘s small sample size, further research is needed to definitively prove this claim

Age as a factor for cognitive decline in patients with glial tumors

Introduction: Cognitive impairment appears in almost all patients with glial tumors during the course of this neuro-oncological disease. There are various reasons for this in regards to the glial tumor: grade of malignancy, rate of growth, molecular nature, mass effect, and presence of perifocal edema. But these factors do not always correlate with the degree of patient’s cognitive impairment. The present study’s aim is to account for age as a factor in the occurrence of cognitive decline in patients with glial tumors.Materials and methods: The study includes thirty two patients diagnosed with a glial tumor, treated operatively in the Neurosurgery Clinic of University hospital „St. Marina“ in Varna between 2019 and 2022 year. Twenty nine of those patients are diagnosed with glioblastoma, two are diagnosed with diffuse astrocytoma and one with astrocytoma grade 3 according to WHO. The mean age of the patients is 58.4 ± 11.4 years. The youngest patient is 25 years old and the oldest is 78 years old. Preoperatively, all patients are subjected to a series of cognitive tests.Results: From the studied sample, patients diagnosed with glioblastoma showed lower cognitive scores compared to the patients diagnosed with other glial tumors. Patients diagnosed with glioblastoma are significantly older than the patients diagnosed with other glial tumors.Conclusion: The older age of patients affected by glioblastoma may be an additional reason beside tumor factors for lower cognitive test outcome compared to patients affected by lower-grade gliomas

Roughening Induced Deconstruction in (100) Facets of CsCl Type Crystals

The staggered 6-vertex model describes the competition between surface roughening and reconstruction in (100) facets of CsCl type crystals. Its phase diagram does not have the expected generic structure, due to the presence of a fully-packed loop-gas line. We prove that the reconstruction and roughening transitions cannot cross nor merge with this loop-gas line if these degrees of freedom interact weakly. However, our numerical finite size scaling analysis shows that the two critical lines merge along the loop-gas line, with strong coupling scaling properties. The central charge is much larger than 1.5 and roughening takes place at a surface roughness much larger than the conventional universal value. It seems that additional fluctuations become critical simultaneously.Comment: 31 pages, 9 figure