Vacuum spacetimes of embedding class two

Doubt is cast on the much quoted results of Yakupov that the torsion vector in embedding class two vacuum space-times is necessarily a gradient vector and that class 2 vacua of Petrov type III do not exist. The rst result is equivalent to the fact that the two second fundamental forms associated with the embedding necessarily commute and has been assumed in most later investigations of class 2 vacuum space-times. Yakupov stated the result without proof, but hinted that it followed purely algebraically from his identity: Rijkl Ckl = 0 where Cij is the commutator of the two second fundamental forms of the embedding.From Yakupov's identity, it is shown that the only class two vacua with non-zero commutator Cij must necessarily be of Petrov type III or N. Several examples are presented of non-commuting second fundamental forms that satisfy Yakupovs identity and the vacuum condition following from the Gauss equation; both Petrov type N and type III examples occur. Thus it appears unlikely that his results could follow purely algebraically. The results obtained so far do not constitute denite counter-examples to Yakupov's results as the non-commuting examples could turn out to be incompatible with the Codazzi and Ricci embedding equations. This question is currently being investigated

System testing levels of Tatar language proficiency

In recent years, a special attention is paid to the change of methodological approaches in teaching the Tatar language as the state language of the Republic of Tatarstan, the achievement of the performance that each student can acquire the language as a means of active communication. This is the relevance of this article. It represents a system of diagnosing the quality of training of students on levels A1, A2, B1, B2. It allows to control the communicative advancements of students according to the main types of speech activity. When preparing the test tasks on the Tatar language for different levels, we relied on the materials of international exams in foreign languages, the experience of teaching of the Tatar language to foreign audience. The present material was approbated by controlling the level advancement of the Tatar language course participants as well as in the diagnosing the level of the Tatar language proficiency of the Russian-speaking pupils in comprehensive secondary school. Introduction of the developed level test is aimed at improving the systems of language certification for the Tatar language and allows to conduct entrance and exit testing in compliance with international standards

The efficacy of combination therapy with mexidol and cerebrolysin in chronic cerebral ischemia

© 2016, Media Sphera. All rights reserved.Objective. To study the impact of combination therapy with mexidol and cerebrolysin on the clinical status of patients with chronic cerebral ischemia (CCI), II stage, in ambulatory conditions. Material and methods. The study included 36 patients with CCI, II stage. In addition to basic therapy, patients received two courses of the mexidol/cerebrolysin combination during 6 weeks with 3 month-interval between the courses. The dynamics of subjective complaints of the patients and objective clinical signs was assessed after each course. The content of 13 chemical elements in the hair was determined by atomic-emission method after the treatment. Results and ?onclusion/ Based on the results of clinical and neurological study, the efficacy of combination therapy with mexidol and cerebrolysin as long-term neuroprotection drugs was shown which manifested a significant reduction in the severity of all major symptoms under the influence of the therapy

Implications of quantitative susceptibility mapping at 7 Tesla MRI for microbleeds detection in cerebral small vessel disease

BACKGROUND: Cerebral microbleeds (MBs) are a hallmark of cerebral small vessel disease (CSVD) and can be found on T2*-weighted sequences on MRI. Quantitative susceptibility mapping (QSM) is a postprocessing method that also enables MBs identification and furthermore allows to differentiate them from calcifications. AIMS: We explored the implications of using QSM at submillimeter resolution for MBs detection in CSVD. METHODS: Both 3 and 7 Tesla (T) MRI were performed in elderly participants without MBs and patients with CSVD. MBs were quantified on T2*-weighted imaging and QSM. Differences in the number of MBs were assessed, and subjects were classified in CSVD subgroups or controls both on 3T T2*-weighted imaging and 7T QSM. RESULTS: 48 participants [mean age (SD) 70.9 (8.8) years, 48% females] were included: 31 were healthy controls, 6 probable cerebral amyloid angiopathy (CAA), 9 mixed CSVD, and 2 were hypertensive arteriopathy [HA] patients. After accounting for the higher number of MBs detected at 7T QSM (Median = Mdn; Mdn7T−QSM = 2.5; Mdn3T−T2 = 0; z = 4.90; p < 0.001) and false positive MBs (6.1% calcifications), most healthy controls (80.6%) demonstrated at least one MB and more MBs were discovered in the CSVD group. CONCLUSIONS: Our observations suggest that QSM at submillimeter resolution improves the detection of MBs in the elderly human brain. A higher prevalence of MBs than so far known in healthy elderly was revealed

Peculiarities of modelling of the enterprise investment attractiveness in the conditions of multicollinearity of predictors

© Medwell Journals, 2017. The study presents an approach to assess the enterprise investment attractiveness based on the econometric modeling of return on assets. The researchers underline the key role of financial indicators in assessing investment attractiveness and propose a system of financial ratios of the enterprise-predictors of return on assets. In the conditions of collinearity of prognostic factors, the researchers offer to implement ridge regression which enables to obtain better prognostic characteristics to preserve reliability and informational value of the modelling. The researchers suggest tools to analyze how predictors of return on assets contribute to the assessment of investment attractiveness whose quality was tested using standard fisher and student tests and the standard error. The results of the empirical evaluations carried out using the Gretl Software confirmed their feasibility for potential investors, shareholders and owners in managing the use of capital effectively

Perceived and mentally rotated contents are differentially represented in cortical depth of V1

Primary visual cortex (V1) in humans is known to represent both veridically perceived external input and internally-generated contents underlying imagery and mental rotation. However, it is unknown how the brain keeps these contents separate thus avoiding a mixture of the perceived and the imagined which could lead to potentially detrimental consequences. Inspired by neuroanatomical studies showing that feedforward and feedback connections in V1 terminate in different cortical layers, we hypothesized that this anatomical compartmentalization underlies functional segregation of external and internally-generated visual contents, respectively. We used high-resolution layer-specific fMRI to test this hypothesis in a mental rotation task. We found that rotated contents were predominant at outer cortical depth bins (i.e. superficial and deep). At the same time perceived contents were represented stronger at the middle cortical bin. These results identify how through cortical depth compartmentalization V1 functionally segregates rather than confuses external from internally-generated visual contents. These results indicate that feedforward and feedback manifest in distinct subdivisions of the early visual cortex, thereby reflecting a general strategy for implementing multiple cognitive functions within a single brain region

Ion-Pair Chromatography for the Determination of Capreomycin Sulfate Components and Related Substances

Chromatographic methods for the analysis of antibiotic degradation products are widely used to evaluate the quality of medicines. Natural multicomponent antibiotics, such as capreomycin, are the most challenging compounds in terms of developing analytical procedures for related substances. Capreomycin sulfate monographs of the leading pharmacopoeias do not contain specifications for related substances. The key requirement concerns the sum of the main components of capreomycin calculated by normalising the peak areas in the test solution chromatogram. Therefore, it is important to develop an analytical procedure for determining not only the main components but also related substances of capreomycin.The aim of the study was to develop an analytical procedure for determining both the main components (IA, IB, IIA, and IIB) and related substances of capreomycin by ion-pair ultra-high-performance liquid chromatography (UHPLC).Materials and methods. This study examined capreomycin sulfate powder, an active pharmaceutical ingredient (API). Capreomycin sulfate solutions were analysed after artificial degradation (alkaline or acid hydrolysis) to demonstrate the resolution, selectivity, and efficiency of the experimental chromatographic system. The authors used an Agilent 1100 liquid chromatography instrument (Agilent Technologies) and chromatographic columns: Kinetex C18, YMC-Triart С18, ACQUITY UPLC BEH C18, ACQUITY UPLC BEH C8, ACQUITY UPLC BEH Phenyl, and ACQUITY UPLC CSH C18 (experimental procedure) or Acclaim C18, Zorbax SB-C18, and XBridge BEH130 C18 (The International Pharmacopoeia procedure).Results. In contrast to pharmacopoeial procedures, which evaluate only the component composition, the experimental procedure under the selected chromatography conditions can determine both the component composition and related substances of capreomycin. This advantage results from substituting a column packed with 1.7 µm particles for a 5 µm column required for pharmacopoeial procedures. The experimental procedure remains suitable for liquid chromatography instruments with a pressure limit of no more than 400 bar in the gradient elution mode with two mobile phases. According to the efficiency and selectivity evaluation, ACQUITY UPLC BEH C18 columns (150 × 2.1 mm, 1.7 μm) provide optimal peak resolution for capreomycin isoforms and related substances after artificial degradation of capreomycin.Conclusions. This experimental procedure based on ion-pair UHPLC may be used in the production and stability testing of capreomycin medicines to evaluate the API quality by the content of its main components and related substances

State of functional systems in patients with ischemic stroke

The purpose of this work is to study features of the ranking of functional systems in patients with ischemic stroke for better understanding of the integrative processes occurring in the body of the patient during dysfunction of cerebral circulation. The study involved 50 patients with acute MRI-verified hemispheric ischemic stroke, mean age 62,0 ± 6,5 years. NIHSS, Barthel and Rankin Scales were used to assess the dynamics of neurological deficit. Changes in vegetative homeostasis were investigated using short recordings of heart rate variability. Hamilton and Spielberger-Hanin questionnaires were used to identify anxiety and depressive disorders. The results were interpreted in the context of the theory of P.K. Anokhin of functional systems in accordance with the metabolic, homeostatic, behavioral, mental and social level of organization of functional systems. According to the study, it was found that 26% of patients on days 2-4 of development of ischemic stroke (IS) noted raising the temperature to 37 ± 0,46. In the study of vegetative homeostasis showed an increase in the proportion of very low frequency in the general spectrum of heart rate variability, which indicates a strengthening of humoral regulation (index VLF (Very Low Frequency) - 755 ±101,6 on the 3rd day and 657 +108,5 - on the 15th day). We have established the fact in the development of acute ischemic stroke that the activity of functional systems (FS) at the behavioral level of organization is effectively replaced by the medical staff and caregivers out of the violations of patients' self-help skills (Barthel Index: 42,0+6,74 on 3rd day and 67,5 ± 7,54 - on the 15th day; Rankin Scale: 3,6+0,51 on 3rd day and 3,0+0,81 - on the 15th day). When analyzing the activity of FS on the mental level of the organization, it was found that the level of anxiety and depressive disorders was directly dependent on the level of neurological deficit. All findings demonstrate the need for an integrative understanding of processes in the patient's body to design optimal treatment and rehabilitation programs.Цель настоящей работы - изучить особенности иерархии функциональных систем у больных с ишемическим инсультом, поскольку при развитии острого нарушения мозгового (ОНМК) необходимо интегративное осмысление процессов, происходящих в организме пациента. В исследовании приняли участие 50 пациентов в остром периоде МРТ-верифицированного полушарного ишемического инсульта (ИИ), средний возраст 62,0±6,5 года. Для оценки динамики неврологического дефицита использовались шкалы NIHSS, Бартел и Рэнкин. Изменения вегетативного гомеостаза исследовались по коротким записям вариабельности ритма сердца. Для выявления тревожно-депрессивных расстройств использовались опросники Гамильтона и Спилбергера-Ханина. Полученные данные были интерпретированы в контексте теории П.К. Анохина о функциональных системах в соответствии с метаболическим, гомеостатическим, поведенческим, психическим и социальным уровнем организации ФС. По результатам исследования было установлено, что у 26% пациентов на 2-4 сутки от развития ИИ отмечалось повышение температуры до 37±0,46. При исследовании вегетативного гомеостаза было выявлено увеличение удельного веса очень низких частот в общем спектре вариабельности ритма сердца, что указывает на усиление гуморальной регуляции (показатель VLF (Very Low Frequency) - 755+101,6 на третий и 657+108,5 - на 15й день). Нами был установлен тот факт, при развитии ОНМК деятельность ФС на поведенческом уровне организации фактически замещается медперсоналом и ухаживающими из-за нарушения у пациентов навыков самообслуживания (индекс Вартел: 42,0+6,74 на 3 день и 67,5+7,54 - на 15й; шкала Ранкина: 3,6+0,51 на 3 день и 3,0+0,81). При анализе деятельности ФС на психическом уровне организации было выяснено, что уровень тревожно-депрессивных расстройств имел прямую зависимость от уровня неврологического дефицита. Все полученные данные демонстрируют необходимость интегративного осмысления процессов в организме пациента для составления оптимальной программы лечения и реабилитации

Vessel distance mapping: A novel methodology for assessing vascular-induced cognitive resilience

The association between cerebral blood supply and cognition has been widely discussed in the recent literature. One focus of this discussion has been the anatomical variability of the circle of Willis, with morphological differences being present in more than half of the general population. While previous studies have attempted to classify these differences and explore their contribution to hippocampal blood supply and cognition, results have been controversial. To disentangle these previously inconsistent findings, we introduce Vessel Distance Mapping (VDM) as a novel methodology for evaluating blood supply, which allows for obtaining vessel pattern metrics with respect to the surrounding structures, extending the previously established binary classification into a continuous spectrum. To accomplish this, we manually segmented hippocampal vessels obtained from high-resolution 7T time-of-flight MR angiographic imaging in older adults with and without cerebral small vessel disease, generating vessel distance maps by computing the distances of each voxel to its nearest vessel. Greater values of VDM-metrics, which reflected higher vessel distances, were associated with poorer cognitive outcomes in subjects affected by vascular pathology, while this relation was not observed in healthy controls. Therefore, a mixed contribution of vessel pattern and vessel density is proposed to confer cognitive resilience, consistent with previous research findings. In conclusion, VDM provides a novel platform, based on a statistically robust and quantitative method of vascular mapping, for addressing a variety of clinical research questions