Optical conductivity of the Kondo insulator YbB_12: Gap formation and low-energy excitations

Optical reflectivity experiments have been conducted on single crystals of the Kondo insulator YbB_12 in order to obtain its optical conductivity, \sigma(\omega). Upon cooling below 70 K, a strong supression of \sigma(\omega) is seen in the far-infrared region, indicating the opening of an energy gap of ~ 25 meV. This gap development is coincident with a rapid decrease in the magnetic susceptibility, which shows that the gap opening has significant influence on magnetic properties. A narrow, asymmetric peak is observed at ~40 meV in \sigma(\omega), which is attributed to optical transitions between the Yb 4f-derived states across the gap. In addition, a broad peak is observed at ~0.25 eV. This peak is attributed to transitions between Yb 4f-derived states and p-d band, and is reminiscent of similar peaks previously observed for rare-earth hexaborides.Comment: 4 pages, 4 figure

Evidence for short-range antiferromagnetic fluctuations in Kondo-insulating YbB12

The spin dynamics of mixed-valence YbB12 has been studied by inelastic neutron scattering on a high-quality single crystal. In the Kondo-insulating regime realized at low temperature, the spectra exhibit a spin-gap structure with two sharp, dispersive, in-gap excitations at E = 14.5 and approximately 20 meV. The lower mode is shown to be associated with short-range correlations near the antiferromagnetic wave vector q0 = (1/2, 1/2, 1/2). Its properties are in overall agreement with those expected for a "spin exciton'' branch in an indirect hybridization gap semiconductor.Comment: 4 pages, 4 figures ; submitted to Physical Review Letter

Perancangan Media Komunikasi Visual Gangs Barbershop Di Bali

Perancangan Media Komunikasi Visual Gangs Barbershop di Bali ini dibuat agar Gangs Barbershop mendapatkan loyalitas dan kepercayaan konsumen. Pada perancangan kali ini digunakan gaya desain American New Wave atau American Postmodern karena sesuai dengan gaya kustom kulture dari Gangs Barbershop ini. Metode yang digunakan adalah metode analisis kualitatif SWOT. Metode ini bertujuan untuk mengetahui kelebihan dan kekurangan dari Gangs Barbershop serta kesempatan atau hambatan yang berasal dari luar/pesaing

Crossword Puzzle Increase Attention of Children with Adhd

Introduction: Attention deficit is one of three main problems of children with Attention Deficit Hyperactivity Disorder (ADHD). Children experience difficulty of paying attention and concentrating to one or more things or objects. As a results these children cannot perform the task well. Crossword puzzle is one of games that may increase attention and concentration. The aim of this study was to analyze the effect of crossword puzzle to increase attention of children with ADHD. Method: Pre-experimental design was employed in this study. The population was ADHD students in Cakra Autisme Therapy. Seven students were recruited by means of purposive sampling. The independent variable was crossword puzzle and the dependent variable was the increase of attention. Data were collected using observation sheet and analyzed using Wilcoxon Signed Rank Test with level of significance of α≤ 0.05. Result: Result showed that crossword puzzle could increase attention. Respondent\u27s attention improved from less to good attention, particularly in playing activities (p=0.014). Analysis: This finding suggests that there was differences of attention between pre and post-test. It can be concluded that crossword puzzle can increase attention of the students with ADHD. Discussion: It is recommended for teachers and parents of ADHD children to give them crossword puzzle game everyday at school or at home. Further studies should involve larger sample size and employs another game not only to increase attention, but also reduce hyperactivity and impulsivity of ADHD child

Stres oksydacyjny indukowany hiperglikemią w cukrzycy ciążowej (GDM)

An imbalance between production of reactive oxygen species (ROS) and their clearance by antioxidant defence mechanisms results in the development of oxidative stress. Biological consequences of this state involve oxidative damage of key cellular components such as nucleic acids, lipids, or proteins and, in turn, impairment of cell and tissue function. Evidence from clinical and experimental studies supports the notion that oxidative stress is one of pathologic factors associated with gestational diabetes mellitus (GDM), metabolic disorder defined as any degree of glucose intolerance with onset or first recognition during pregnancy. It has been established that high blood glucose concentrations in diabetic pregnancy induce oxidative stress by several mechanisms, including an enhanced ROS production in mitochondria, the polyol pathway and the hexosamine pathway, as well as protein kinase C (PKC) activation and an advanced glycation end-products (AGEs) formation, and changes in biomarkers of free radical-induced damage and antioxidant defences have been detected in maternal diabetes. Moreover, hyperglycaemia-induced oxidative stress is related with some congenital anomalies in diabetic pregnancy. The current article provides an overview how oxidative stress is related to GDM, with special emphasis on the involvement of the hyperglycaemia-induced mechanisms in ROS overproduction, followed by discussion of indicators of oxidative stress. In addition, the relationship between oxidative stress and congenital malformations in diabetic pregnancy is described.Brak równowagi między produkcją reaktywnych form tlenu (ROS) a ich usunięciem przez antyoksydacyjne mechanizmy obronne prowadzi do rozwoju stresu ok­sydacyjnego. Biologicznymi konsekwencjami tego stanu są oksydacyjne uszkodzenia kluczowych składników komórkowych, takich jak kwasy nukleinowe, białka lub lipidy, które prowadzą do upośledzenia funkcji komórek i tkanek. Dowody pochodzące z badań klinicznych i eksperymentalnych popierają koncepcję, że stres oksydacyjny jest jednym z patologicznych czynników związanych z cukrzycą ciążową (GDM), definiowaną jako różny stopień zaburzeń tolerancji węglowodanów po raz pierwszy rozpoznany lub rozwijający się podczas ciąży. Ustalono, że wysokie stężenia glukozy we krwi kobiet z GDM indukują stres oksydacyjny poprzez kilka mechanizmów, w tym zwiększoną produkcję ROS w mitochondriach, szlak poliolowy, szlak heksozoaminy, aktywację kinazy białkowej C (PKC) oraz tworzenie końcowych produktów zaawansowanej glikacji (AGEs). Zmiany zarówno w biomarkerach uszkodzeń oksydacyjnych, jak i antyoksydacyjnym systemie obronnym były wykryte u pacjentek z GDM. Ponadto stres oksydacyjny indukowany hiperglikemią w GDM jest związany z roz­wojem wad wrodzonych płodu. Niniejszy artykuł stanowi podsumowanie wiedzy o związku stresu oksydacyjnego z cukrzycą ciążową, ze szczególnym podkreśleniem udziału mechanizmów indukowanych hiperglikemią, które prowadzą do nadprodukcji ROS, oraz omówieniem wskaźników stresu oksydacyjnego. Opisano także związek między stresem oksydacyjnym a występowaniem wad wrodzonych płodu podczas cukrzycy w ciąży

Analisis Peluang Curah Hujan Untuk Penetapan Pola Dan Waktu Tanam Serta Pemilihan Jenis Komoditi Yang Sesuai Di Desa Masbagik Kecamatan Masbagik Kabupaten Lombok Timur

Climatic factor, such as rainfall, greatly contributes to the availability of water for crops. Farmers set a schedule and cropping patterns based on habits, such as the period of rainy month. This method is lack precision on determining crops pattern and often increasing the risk of crop failure. This study aims to determine rainfall probability in Masbagik village on growing season of 2015-2016. Research method was descriptive analytical method. Results of this research revealed that the general rainfall pattern of the study area was still following general pattern of the previous year. Rain probability that approached natural precipitation at the field of study was 50%, with the highest limits at December by 304.5 mm and the lowest at October by 37 mm, while general rainfall probability was normal. Rainy season was predicted to start at mid-November and end at early June, while dry season occurs from early May and end in early November. Recommended scenario of the first growing season for the crop is starting at mid-November until the end of February and the second growing season start at mid-March until June 2015. Moreover, planting time for growing rice can be carried out at mid-October, while from early March growing crops is more suitable. Keywords: rainfall, type of commodity, cropping pattern &nbsp

Ocena leukocytarnej ekspresji SIRT1 u kobiet ze zdiagnozowaną cukrzycą ciążową (GDM) w trzecim trymestrze ciąży

Background. Sirtuin 1 (SIRT1), a NAD+-dependent deacetylase, has been implicated as a key regulator of glucose/lipid metabolism, insulin secretion as well as adiponectin production and inflammation in metabolic disorders, including type 2 diabetes mellitus (T2DM). However, its role in gestational diabetes mellitus (GDM) remains widely unknown. Since GDM is associated with inflammation, the aim of this study was to determine whether leukocyte SIRT1 mRNA expression is alteredin GDM women in the third trimester of pregnancy, and whether this change is correlated with clinical characteristics of patients. Methods. Leukocytes were isolated from the blood of GDM (n = 135) and normal glucose tolerant (NGT;n = 52) pregnant women. After extracting RNA from leukocytes, a quantitative real-time polymerase chain reaction (qRT-PCR) approach was performed to assess SIRT1 gene expression in these cells. Univariate regression analyses were applied to investigate correlations between SIRT1 expression and clinic parameters of patients. Results. Leukocyte SIRT1 mRNA was increased 1.7-foldin the GDM vs. NGT subjects (p = 0.001) and it positively correlated with 2 h glucose concentration during oral glucose tolerance test (OGTT) in the whole studygroup and negatively correlated with pregnancy agein the GDM and NGT groups. The positive association was also observed between SIRT1 mRNA and plasma high density lipoprotein (HDL) cholesterol level in the NGT subjects. Conclusions. GDM is accompanied by leukocyte SIRT1 mRNA over expression associated with hyperglycemia. Additionally, there is a close and beneficial relationship between enhanced leukocyte SIRT1 expression and increased plasma HDL-cholesterol level during normal pregnancy.Wstęp. Sirtuina 1 (SIRT1) jest NAD+-zależną deacetylazą, która odgrywa istotną rolę w regulacji metabolizmu węglowodanów i lipidów, sekrecji insuliny, produkcji adiponektyny oraz stanu zapalnego w chorobach metabolicznych, w tym cukrzycy typu 2 (T2DM). Do tej pory brak jest informacji o związku leukocytarnej SIRT1 z cukrzycą ciążową (GDM). Zważywszy związek SIRT1 ze stanem zapalnym, celem badania było określenie zmian w poziomie ekspresji SIRT1 mRNA w leukocytach kobiet z GDM w trzecim trymestrze ciąży i skorelowanie ich z klinicznymi parametrami pacjentek. Materiały i metody. Leukocyty wyizolowano z krwi pobranej od kobiet ciężarnych z GDM (n = 135) oraz kobiet ciężarnych z prawidłową gospodarką węglowodanową (NGT; n = 52). Po ekstrakcji RNA z leukocytów poziom ekspresji SIRT1 mRNA w tych komórkach określono metodą ilościowego qRT-PCR. Korelacje między ekspresją SIRT1 a klinicznymi parametrami pacjentek analizowano z wykorzystaniem regresji jednokrotnych. Wyniki. Ekspresja SIRT1 była 1,7-krotnie wyższa w leukocytach kobiet z GDM niż w grupie kobiet z NGT (p = 0,001) i dodatnio korelowała ze stężeniem glukozy w 2. godzinie testu doustnego obciążenia glukozą (OGTT) w całej badanej populacji pacjentek oraz ujemnie korelowała z wiekiem ciąży kobiet zarówno w grupie GDM, jak i NGT (p < 0,05). Stwierdzono również istotną statystycznie dodatnią korelację międzyekspresją SIRT1 a stężeniem cholesterolu frakcji HDL w grupie NGT (p < 0,05). Wnioski. GDM towarzyszy podwyższona ekspresja SIRT1 w leukocytach, która jest związana z hiperglikemią. Ponadto zaobserwowano istnienie bliskiego i korzystnego związku między podwyższonymi poziomami ekspresji SIRT1 a cholesterolem frakcji HDLu kobiet z prawidłowym przebiegiem ciąży

Indirect and direct energy gaps in the Kondo semiconductor YbB12

Optical conductivity [$\sigma(\omega)$] of the Kondo semiconductor YbB$_{12}$ has been measured over wide ranges of temperature ($T$=8$-$690 K) and photon energy ($\hbar \omega \geq$ 1.3 meV). The $\sigma(\omega)$ data reveal the entire crossover of YbB$_{12}$ from a metallic electronic structure at high $T$ into a semiconducting one at low $T$. Associated with the gap development in $\sigma(\omega)$, a clear onset is newly found at $\hbar\omega$=15 meV for $T \leq$ 20 K. The onset energy is identified as the gap width of YbB$_{12}$ appearing in $\sigma(\omega)$. This gap in \sigma(\omega)$is interpreted as the indirect gap, which has been predicted in the band model of Kondo semiconductor. On the other hand, the strong mid-infrared (mIR) peak observed in$\sigma(\omega)$ is interpreted as arising from the direct gap. The absorption coefficient around the onset and the mIR peak indeed show characteristic energy dependences expected for indirect and direct optical transitions in conventional semiconductors.Comment: 4 pages, 3 figures, submitted to J. Phys. Soc. Jp