Dynamics of Vortex Core Switching in Ferromagnetic Nanodisks

Dynamics of magnetic vortex core switching in nanometer-scale permalloy disk, having a single vortex ground state, was investigated by micromagnetic modeling. When an in-plane magnetic field pulse with an appropriate strength and duration is applied to the vortex structure, additional two vortices, i.e., a circular- and an anti-vortex, are created near the original vortex core. Sequentially, the vortex-antivortex pair annihilates. A spin wave is created at the annihilation point and propagated through the entire element; the relaxed state for the system is the single vortex state with a switched vortex core.Comment: to appear in Appl. Phys. Let

Changing teaching techniques and adapting new technologies to improve student learning in an introductory meteorology and climate course

Responding to the call for reform in science education, changes were made in an introductory meteorology and climate course offered at a large public university. These changes were a part of a larger project aimed at deepening and extending a program of science content courses that model effective teaching strategies for prospective middle school science teachers. Therefore, revisions were made to address misconceptions about meteorological phenomena, foster deeper understanding of key concepts, encourage engagement with the text, and promote inquiry-based learning. Techniques introduced include: use of a flash cards, student reflection questionnaires, writing assignments, and interactive discussions on weather and forecast data using computer technology such as Integrated Data Viewer (IDV). The revision process is described in a case study format. Preliminary results (self-reflection by the instructor, surveys of student opinion, and measurements of student achievement), suggest student learning has been positively influenced. This study is supported by three grants: NSF grant No. 0202923, the Unidata Equipment Award, and the Lucia Harrison Endowment Fund

Мовні реалії іншого часу і простору (про особливості слововживання у творах Івана Багряного)

The structure of Earthʼs deep inner core has important implications for core evolution, since it is thought to be related to the early stages of core formation. Previous studies have suggested that there exists an innermost inner core with distinct anisotropy relative to the rest of the inner core. Using an extensive new data set of handpicked absolute travel time observations of the inner core phase PKIKP, we find that the data are best explained by variations in anisotropy between two hemispheres and do not require an innermost inner core. We demonstrate that observations of an innermost inner core are an artifact from averaging over lateral anisotropy variations. More significantly we show that hemispherical variations in anisotropy, previously only imaged in the upper inner core, continue to its centre. The eastern region has 0.5–1.5% anisotropy, whereas the western region has 3.5–8.8% anisotropy increasing with depth, with a slow direction at 57–61° to the Earthʼs rotation axis at all depths. Such anisotropy is consistent with models of aligned hcp or bcc iron aggregates

Histopathological placental lesions in mild gestational hyperglycemic and diabetic women

Objective: To investigate and compare the incidence of histopathological placental lesions in mild gestational hyperglycemia, gestational diabetes and overt diabetes at term and preterm gestation.Research design and methods: One-hundred-and-thirty-one placental samples were collected from Diabetes mellitus (DM) positive screened patients. Two diagnostic tests, glycemic profile and 100 g oral glucose tolerance test (OGTT) in parallel identified 4 groups normoglycemic, mild gestational hyperglycemia (MGH), gestational DM (GDM) or overt DM (DM). Placental tissue specimens and sections from 4 groups were obtained by uniform random sampling and stained with hematoxylin-eosin.Results: Placentas from MGH group presented 17 types of histopathological change and higher rates of syncytial nodes and endarteritis. GDM placentas presented only nine types of histopathological change, high rates of dysmaturity, low rates of calcification and no syncytial nodes. Overt DM placentas showed 22 types of histopathological change, 21 of which were present in the preterm period. There were histopathological similarities between MGH and DM placentas, but the former exhibited a higher incidence of endarteritis, which has been described as a post-mortem phenomenon.Conclusion: Our results confirmed that the distinct placental changes associated with DM and MGH depend on gestational period during which the diabetic insult occurs. It may reasonably be inferred that subclinical maternal hyperglycemia during pregnancy, as showed in MGH group, is responsible for increased placental endarteritis, a postmortem lesion in the live fetus

Who acquires infection from whom and how? Disentangling multi-host and multi-mode transmission dynamics in the 'elimination' era

Multi-host infectious agents challenge our abilities to understand, predict and manage disease dynamics. Within this, many infectious agents are also able to use, simultaneously or sequentially, multiple modes of transmission. Furthermore, the relative importance of different host species and modes can itself be dynamic, with potential for switches and shifts in host range and/ or transmission mode in response to changing selective pressures, such as those imposed by disease control interventions. The epidemiology of such multi-host, multi-mode infectious agents thereby can involve a multi-faceted community of definitive and intermediate/secondary hosts or vectors, often together with infectious stages in the environment, all of which may represent potential targets, as well as specific challenges, particularly where disease elimination is proposed. Here, we explore, focusing on examples fromboth human and animal pathogen systems, why and how we should aim to disentangle and quantify the relative importance of multi-host multi-mode infectious agent transmission dynamics under contrasting conditions, and ultimately, how this can be used to help achieve efficient and effective disease control. This article is part of the themed issue 'Opening the black box: re-examining the ecology and evolution of parasite transmission'

Evaluation of neonatally-induced mild diabetes in rats: Maternal and fetal repercussions

Many experimental studies have been performed to evaluate mild diabetes effects. However, results are divergent regarding glycemia and insulin measurement, fetal macrossomia, and placental weights. The aim was to investigate repercussions of neonatally-induced mild diabetes on the maternal organism and presence of congenital defects in their offspring in other mild diabetes model. On the day of birth, female offspring were distributed into two groups: Group streptozotocin (STZ): received 100 mg STZ/kg body weight, and Control Group: received vehicle in a similar time period. Maternal weights and glycemias were determined at days 0, 7, 14 and 21 of pregnancy. At day 21 of pregnancy, the rats were anesthetized and a laparotomy was performed to weigh and analyze living fetuses and placentas. The fetuses were classified as small (SPA), appropriate (APA) and large (LPA) for pregnancy age. Fetuses were also analyzed for the presence of external anomalies and processed for skeletal anomaly and ossification sites analysis. Statistical significance was considered as p < 0.05. In STZ group, there was increased glycemia at 0 and 14 days of pregnancy, lower weights throughout pregnancy, higher placental weight and index, an increased proportion of fetuses classified as SPA and LPA, and their fetuses presented with an increased frequency of abnormal sternebra, and absent cervical nuclei, which were not enough to cause the emergence of skeletal anomalies. Thus, this study shows that mild diabetes altered fetal development, characterized by intrauterine growth restriction. Further, the reached glycemia does not lead to any major congenital defects in the fetuses of streptozotocin-induced mild diabetic rats

Batek playing Batek for tourists at Peninsular Malaysia’s national park

The Batek are a foraging-trading people living in and around Peninsular malaysia’s largest national park, taman Negara. In recent years some of their semi-permanent camps near the park headquarters at Kuala tahan have become tourist attractions. Batek residents allow groups of malaysian and foreign tourists to visit, and they demonstrate some of their specialised skills, including shooting blowpipes and making fire with rattan vines and dry wood, as well as selling handicrafts. In this article we examine the reasons why some Batek participate in the tourist business, how they integrate it into their overall economy, and how they preserve their distinctive cultural values and practices while offering a simplified picture of their culture to curious outsiders

S-, P- and D-wave resonances in positronium-sodium and positronium-potassium scattering

Scattering of positronium (Ps) by sodium and potassium atoms has been investigated employing a three-Ps-state coupled-channel model with Ps(1s,2s,2p) states using a time-reversal-symmetric regularized electron-exchange model potential fitted to reproduce accurate theoretical results for PsNa and PsK binding energies. We find a narrow S-wave singlet resonance at 4.58 eV of width 0.002 eV in the Ps-Na system and at 4.77 eV of width 0.003 eV in the Ps-K system. Singlet P-wave resonances in both systems are found at 5.07 eV of width 0.3 eV. Singlet D-wave structures are found at 5.3 eV in both systems. We also report results for elastic and Ps-excitation cross sections for Ps scattering by Na and K.Comment: 9 pages, 5 figures, Accepted in Journal of Physics

Repercussions of mild diabetes on pregnancy in Wistar rats and on the fetal development

<p>Abstract</p> <p>Background</p> <p>Experimental models are necessary to elucidate diabetes pathophysiological mechanisms not yet understood in humans. Objective: To evaluate the repercussions of the mild diabetes, considering two methodologies, on the pregnancy of Wistar rats and on the development of their offspring.</p> <p>Methods</p> <p>In the 1st induction, female offspring were distributed into two experimental groups: Group streptozotocin (STZ, n = 67): received the β-cytotoxic agent (100 mg STZ/kg body weight - sc) on the 1st day of the life; and Non-diabetic Group (ND, n = 14): received the vehicle in a similar time period. In the adult life, the animals were mated. After a positive diagnosis of pregnancy (0), female rats from group STZ presenting with lower glycemia than 120 mg/dL received more 20 mg STZ/kg (ip) at day 7 of pregnancy (2nd induction). The female rats with glycemia higher than 120 mg/dL were discarded because they reproduced results already found in the literature. In the mornings of days 0, 7, 14 and 21 of the pregnancy glycemia was determined. At day 21 of pregnancy (at term), the female rats were anesthetized and killed for maternal reproductive performance and fetal development analysis. The data were analyzed using Student-Newman-Keuls, Chi-square and Zero-inflated Poisson (ZIP) Tests (p < 0.05).</p> <p>Results</p> <p>STZ rats presented increased rates of pre (STZ = 22.0%; ND = 5.1%) and post-implantation losses (STZ = 26.1%; ND = 5.7%), reduced rates of fetuses with appropriate weight for gestational age (STZ = 66%; ND = 93%) and reduced degree of development (ossification sites).</p> <p>Conclusion</p> <p>Mild diabetes led a negative impact on maternal reproductive performance and caused intrauterine growth restriction and impaired fetal development.</p

Animal models for clinical and gestational diabetes: maternal and fetal outcomes

<p>Abstract</p> <p>Background</p> <p>Diabetes in pregnant women is associated with an increased risk of maternal and neonatal morbidity and remains a significant medical challenge. Diabetes during pregnancy may be divided into clinical diabetes and gestational diabetes. Experimental models are developed with the purpose of enhancing understanding of the pathophysiological mechanisms of diseases that affect humans. With regard to diabetes in pregnancy, experimental findings from models will lead to the development of treatment strategies to maintain a normal metabolic intrauterine milieu, improving perinatal development by preventing fetal growth restriction or macrosomia. Based on animal models of diabetes during pregnancy previously reported in the medical literature, the present study aimed to compare the impact of streptozotocin-induced severe (glycemia >300 mg/dl) and mild diabetes (glycemia between 120 and 300 mg/dl) on glycemia and maternal reproductive and fetal outcomes of <it>Wistar </it>rats to evaluate whether the animal model reproduces the maternal and perinatal results of clinical and gestational diabetes in humans.</p> <p>Methods</p> <p>On day 5 of life, 96 female <it>Wistar </it>rats were assigned to three experimental groups: control (n = 16), severe (n = 50) and mild diabetes (n = 30). At day 90 of life, rats were mated. On day 21 of pregnancy, rats were killed and their uterine horns were exposed to count implantation and fetus numbers to determine pre- and post-implantation loss rates. The fetuses were classified according to their birth weight.</p> <p>Results</p> <p>Severe and mild diabetic dams showed different glycemic responses during pregnancy, impairing fetal glycemia and weight, confirming that maternal glycemia is directly associated with fetal development. Newborns from severe diabetic mothers presented growth restriction, but mild diabetic mothers were not associated with an increased rate of macrosomic fetuses.</p> <p>Conclusion</p> <p>Experimental models of severe diabetes during pregnancy reproduced maternal and fetal outcomes of pregnant women presenting uncontrolled clinical diabetes. On the other hand, the mild diabetes model caused mild hyperglycemia during pregnancy, although it was not enough to reproduce the increased rate of macrosomic fetuses seen in women with gestational diabetes.</p