165 research outputs found
Conductivity, weak ferromagnetism and charge instability in single crystal
The temperature dependence of resistivity, magnetization and electron-spin
resonance of the single crystal were measured in temperature
range of . Magnetization hysteresis in applied magnetic field
up to 0.7 T at , irreversible temperature behavior of
magnetization and resistivity were found . The obtained data were explained in
terms of degenerate tight binding model using random phase approximation. The
contribution of holes in and bands of manganese ions to the
conductivity, optical absorbtion spectra and charge instability in were studied. Charge susceptibility maxima resulted from the competition of
the on-site Coulomb interaction between the holes in different orbitals and
small hybridization of sub-bands were calculated at .Comment: 6 pages, 12 figure
Effects of processing parameters on the morphology, structure, and magnetic properties of Cu1−xFexCr2Se4 nanoparticles synthesized with chemical methods
Cu1−xFexCr2Se4 nanoparticles with x = 0, 0.2, and 0.4 were synthesized via thermal decomposition of metal nitrate or chloride salts and selenium powder using different precursor compositions and processing details. Single crystalline nano-belts or nano-rods coexist in the synthesized powder samples with hexagon-shaped plates in dependence on the precursor composition. The belts gathered into conglomerates forming “hierarchical” particles. Visible magnetic circular dichroism (MCD) of Cu1−xFexCr2Se4 nanoparticles embedded into a transparent matrix was investigated for the first time. The similarity of the MCD spectra of all samples showed the similarity of the nanoparticles electronic structure independent of their morphology. Basing on the MCD spectral maxima characteristics, electron transitions from the ground to the excited states were identified with the help of the conventional band theory and the multi-electron approach
The last frontier: Catch records of white sharks (carcharodon carcharias) in the northwest pacific ocean
White sharks are highly migratory apex predators, globally distributed in temperate, sub-tropical, and tropical waters. Knowledge of white shark biology and ecology has increased recently based on research at known aggregation sites in the Indian, Atlantic, and Northeast Pacific Oceans; however, few data are available for the Northwest Pacific Ocean. This study provides a meta-analysis of 240 observations of white sharks from the Northwest Pacific Ocean between 1951 and 2012. Records comprise reports of bycatch in commercial fisheries, media accounts, personal communications, and documentation of shark-human interactions from Russia (n = 8), Republic of Korea (22), Japan (129), China (32), Taiwan (45), Philippines (1) and Vietnam (3). Observations occurred in all months, excluding October-January in the north (Russia and Republic of Korea) and July-August in the south (China, Taiwan, Philippines, and Vietnam). Population trend analysis indicated that the relative abundance of white sharks in the region has remained relatively stable, but parameterization of a 75% increase in observer effort found evidence of a minor decline since 2002. Reliably measured sharks ranged from 126–602 cm total length (TL) and 16–2530 kg total weight. The largest shark in this study (602 cm TL) represents the largest measured shark on record worldwide. For all countries combined the sex ratio was non-significantly biased towards females (1∶1.1; n = 113). Of 60 females examined, 11 were confirmed pregnant ranging from the beginning stages of pregnancy (egg cases) to near term (140 cm TL embryos). On average, 6.0±2.2 embryos were found per litter (maximum of 10) and gestation period was estimated to be 20 months. These observations confirm that white sharks are present in the Northwest Pacific Ocean year-round. While acknowledging the difficulties of studying little known populations of a naturally low abundance species, these results highlight the need for dedicated research to inform regional conservation and management planning
Particle Size Distribution Controls the Threshold Between Net Sediment Erosion and Deposition in Suspended Load Dominated Flows
The central problem of describing most environmental and industrial flows is predicting when material is entrained into, or deposited from, suspension. The threshold between erosional and depositional flow has previously been modeled in terms of the volumetric amount of material transported in suspension. Here a new model of the threshold is proposed, which incorporates (i) volumetric and particle size limits on a flow's ability to transport material in suspension, (ii) particle size distribution effects, and (iii) a new particle entrainment function, where erosion is defined in terms of the power used to lift mass from the bed. While current suspended load transport models commonly use a single characteristic particle size, the model developed herein demonstrates that particle size distribution is a critical control on the threshold between erosional and depositional flow. The new model offers an order of magnitude, or better, improvement in predicting the erosional‐depositional threshold and significantly outperforms existing particle‐laden flow models
Sediment Resuspension Due to Near-Bed Turbulent Effects: A Deep Sea Case Study on the Northwest Continental Slope of Western Australia
Sediment transport equations often consider a mean velocity threshold for the initiation of sediment motion and resuspension, ignoring event‐based turbulent bursting processes. However, laboratory experiments have suggested that near‐bed sediment resuspension is influenced by intermittent turbulent coherent structures. In the field, accessibility constraints for deployment of easily operated equipment has largely prevented further identification and understanding of such processes, which may contribute to resuspension in the marine environment. Field experiments were conducted on the Northwest Slope, Australia, under conditions where the mean current velocities were below the estimated and measured time‐averaged critical velocity to investigate the relationship between near‐bed turbulent coherent structures and sediment resuspension. Results indicate that sediment resuspension occur even when velocities are below the estimated and measured mean critical values. The majority of turbulent sediment flux is due to ejection and sweep events, with lesser contributions from up‐acceleration and down‐deceleration (vertical flow) events. Spectral and quadrant analysis indicated the anisotropic and intermittent nature of Reynolds stresses, and wavelet transform revealed a group of turbulent bursting sequences associated with sediment resuspension. These observations, in flow conditions where resuspension was not expected to occur based on mean threshold concepts, reveal that intermittent turbulent events control sediment resuspension rather a single time‐averaged critical velocity. This highlights the need of considering turbulence as a significant factor in sediment resuspension and should be further investigated for inclusion into future sediment transport modeling
Novel GLIS3 mutation in patient with neonatal diabetes mellitus and congenital hypothyroidism (NDH-syndrome)
Mutations in the GLIS3 gene encoding the GLIS3 transcription factor are cause of a rare syndromic form of neonatal diabetes mellitus (NDM) with congenital hypothyroidism. Additional features include congenital glaucoma, hepatic fibrosis, polycystic kidneys, developmental delay and other anomalies. This disease in foreign literature is called NDH-syndrome (Neonatal diabetes and Hypothyroidism syndrome).We present the description of a patient with this syndrome with novel homozygous GLIS3 mutation.Our patient is a female, who was born with a weight of 1680 gr, length of 44 cm to consanguineous parents. She developed diabetes on 2 day after birth, requiring continuous intravenous insulin. On day 5 of life hypothyroidism was identified. Thyroid anatomy was normal on ultrasound scan. NDH syndrome was suspected.Genetic analysis revealed a novel homozygous mutation c.1836delT, p.Ser612ArgfsTer33 in exon 5 in GLIS3 gene.To date, the patient is followed up for 4 years in total. Currently, growth retardation, psychomotor and speech development persist. Carbohydrate metabolism and thyroid profile has been subcompensated against the background of replacement therapy. No other components of the syndrome have been identified.In this report, we have demonstrated the features of the neonatal diabetes mellitus in a patient with a defect in the GLIS3 gene. Early genetic verification of the diagnosis contributes to the timely starting of personalized therapy, can improve the quality of life of such patients, and, given the nature of inheritance, is necessary for medical genetic counseling of the family
ПСИХОЛОГИЧЕСКИЕ ХАРАКТЕРИСТИКИ БОЛЬНЫХ ХРОНИЧЕСКОЙ СЕРДЕЧНОЙ НЕДОСТАТОЧНОСТЬЮ В ПЕРИОД ОЖИДАНИЯ ТРАНСПЛАНТАЦИИ СЕРДЦА
Introduction. Numerous studies have established the role of psychological factors in the development, treatment, prognosis of the cardiovascular diseases, as well as in formation of compliance and the quality of patients’ lives. However, few of any psychological studies of patients with chronic heart failure (CHF) waiting for transplantation were carried out, despite the obvious need for reliable psychosocial assessments in the preoperative period and development of psychological support programs. In view of the foregoing, a pilot screening study aimed at assessing the state of the cognitive and affective spheres, personal characteristics of patients with CHFwaiting for the HTas wellanalyzing the relationship between psychological, medical and biological characteristics of patients.Material and methods. 30 patients withCHF took part in the study at theFederal State-Funded Institution «Federal Almazov North-West Medical Research Centre» (Saint-Petersburg). The authors’ structured interviews and psychodiagnostic methods were used in the study: «The index of well-being», (WHO, 1999), «The Brief Neuropsychological Cognitive Examination» (BNCE), «The Zung Self-Rating Depression Scale» (SDS), «The State-Trait Anxiety Inventory» (STAI), «Test the Big Five» (BIG V). Statistical data processing was performed using the Mann–Whitney U criterion and the Spearman correlation (SPSS v. 20.0).Results. Absence of violations of cognitive functions was revealed in 23 % of respondents, mild degree of cognitive deficiency – in 60 %, average degree – in 17 %. The lowest average scores were obtained in the BNCE subtests, reflecting the success of active attention, visual-spatial memory, psychomotorics, abstract thinking.The average group index of depression was 45.9±7.2 (normative level). A detailed analysis showed that absence of signs of depression occurred in 74 % of patients, subdepression – in 23 %, moderately expressed depression – in 3 %. In the entire sample, the average level of situational anxiety prevailed (42.4±6.8) with personal anxiety (39.7±8.1). According to the averaged scales of the BIG V questionnaire, moderately pronounced extroversion features predominated in the patient’s personality structure. The relationship between BNCE indices and duration of chronic HF (r = –0.676, p <0.001) was revealed. A statistically significant reduction in the overall level of cognitive function in patients with concomitant diabetes mellitus was found in comparison with patients without it (U = 61) at p = 0.033; According to the data of SDS depressive symptoms in patients with IHD are more pronounced in comparison with patients with dilated cardiomyopathy U = 47 (p = 0.019).Введение. В многочисленных исследованиях показана роль психологических факторов в развитии, течении, лечении, прогнозе заболеваний сердечно-сосудистой системы, в формировании комплаенса и качества жизни больных. Однако психологические исследования больных хронической сердечной недостаточностью (ХСН) в период ожидания трансплантации органа практически не проводились, несмотря на их очевидную необходимость для совершенствования психосоциальной оценки в предоперационном периоде и разработки программ психологического сопровождения. В связи с этим проведено пилотное скрининговое исследование, имеющее целью оценить состояние когнитивной и аффективной сферы, характеристики личности больных ХСН, находящихся в листе ожидания трансплантации сердца, а также взаимосвязь психологических и медико-биологических характеристик больных.Материал и методы. В СЗФМИЦ им. В. А. Алмазова (Санкт-Петербург) исследованы 30 пациентов с диагнозом ХСН 2б. Использовались авторское структурированное интервью и психодиагностические методы «Индекс общего самочувствия» (ВОЗ, 1999), тестовая батарея «Краткое нейропсихологическое обследование когнитивной сферы» (КНОКС), «Шкала самооценки депрессии» (SDS), «Шкала реактивной и личностной тревожности» (STAI), личностный опросник «Большая пятерка» (BIGV). Статистическая обработка данных произведена с помощью U-критерия Манна–Уитни и корреляции Спирмана («SPSS v. 20.0»).Результаты исследования. Отсутствие нарушений когнитивных функций выявлено у 23 % респондентов, легкая степень когнитивного дефицита – у 60 %, средняя степень – у 17 %. Наиболее низкие средние оценки получены в субтестах КНОКС, отражающих успешность активного внимания, зрительно-пространственной памяти, психомоторики, абстрактного мышления. Средний групповой показатель выраженности депрессии составил 45,9±7,2 (нормативный уровень). Детальный анализ показал отсутствие признаков депрессии у 74 % пациентов, субдепрессию – у 23 %, умеренно выраженную депрессию – у 3 %. Во всей выборке преобладал средний уровень ситуативной тревожности (42,4±6,8) и личностной тревожности (39,7±8,1). Согласно полученным данным, в структуре личности пациентов преобладали умеренно выраженные черты экстраверсии. Выявлена связь между показателями КНОКС и продолжительностью ХСН (r =–0,676, p<0,001). Обнаружено статистически значимое снижение общего показателя состояния когнитивных функций у пациентов с сопутствующим сахарным диабетом по сравнению с пациентами без него (U=61) (р=0,033); показатель депрессии, согласно данным методики SDS, у больных ИБС значимо выше в сравнении с больными с дилатационной кардиомиопатией (U=47) (р=0,019)
КЛИНИЧЕСКИЙ ОПЫТ ПРИМЕНЕНИЯ МЕДИКАМЕНТОЗНЫХ ПРЕПАРАТОВ ПРИ ПОДГОТОВКЕ К КОЛОНОСКОПИИ
Bowel preparation remains an important issue despite vast clinical experience in this field.Methods. 530 patients were included in retrospective analysis. 234 (44.2 %) patients in group 1 used sodium phosphate (SP) for bowel preparation, 176 (33.2 %) patients in group 2 used polyethylene glycol (PEG), 120 (22.6 %) patients used castor oil. Quality of bowel preparation was assessed according to following grading system: «good», «acceptable», «bad».Results. «Good», «acceptable», «bad» bowel preparation was observed in following number of patients: 160 (68.4 %), 46 (19.7 %) and 28 (12 %) patients who used SP, 38.6, 40.3 and 20.1 % who used PEG and 43.3, 20.8, 35.8 % who used castor oil. Results of «good» preparation were significantly better in patients who used SP comparing to other treatment groups.Conclusions. Better bowel preparation with SP was observed in our study, though results need to be validated in randomized trials.Выбор оптимальных методов подготовки пациентов к колоноскопии остается актуальной проблемой, несмотря на многолетний опыт в данной области.Методы. Ретроспективно проанализированы результаты подготовки к колоноскопии 530 пациентов, находящихся на стационарном лечении. Пациенты 1-й группы – 234 (44,2 %) больных – для подготовки к колоноскопии получали препарат фосфата натрия, во 2-й группе – 176 (33,2 %) человек использовали полиэтиленгликоль (ПЭГ), 3-я группа – 120 (22,6 %) пациентов – применяли касторовое масло. Качество подготовки оценивали согласно степени визуализации стенки толстого кишечника на всем протяжении при каждом эндоскопическом исследовании и описывали как «отличную», «удовлетворительную» или «плохую».Результаты. У большей доли пациентов – 160 (68,4 %) человек, которые получали фосфат натрия, во всех сегментах толстой кишки подготовка была признана «отличной», у 46 (19,7 %) оценена как «удовлетворительная», у 28 (12 %) – как «плохая». Аналогичные показатели для ПЭГ составили 38,6; 40,3 и 20,1 % соответственно, для касторового масла – 43,3; 20,8; 35,8 %. Различия были достоверны по показателю «отличной» подготовки в пользу препарата фосфата натрия по сравнению с двумя другими исследуемыми препаратами.Выводы. Отмечено преимущество подготовки кишечника препаратом фосфата натрия, которое требуется подтвердить в рандомизированных исследованиях
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