4,931 research outputs found
Phonon Softening and Direct to Indirect Bandgap Crossover in Strained Single Layer MoSe2
Motivated by recent experimental observations of Tongay et al. [Tongay et
al., Nano Letters, 12(11), 5576 (2012)] we show how the electronic properties
and Raman characteristics of single layer MoSe2 are affected by elastic biaxial
strain. We found that with increasing strain: (1) the E' and E" Raman peaks
(E1g and E2g in bulk) exhibit significant red shifts (up to 30 cm-1), (2) the
position of the A1' peak remains at 180 cm-1 (A1g in bulk) and does not change
considerably with further strain, (3) the dispersion of low energy flexural
phonons crosses over from quadratic to linear and (4) the electronic band
structure undergoes a direct to indirect bandgap crossover under 3% biaxial
tensile strain. Thus the application of strain appears to be a promising
approach for a rapid and reversible tuning of the electronic, vibrational and
optical properties of single layer MoSe2 and similar MX2 dichalcogenides.Comment: http://link.aps.org/doi/10.1103/PhysRevB.87.12541
Visual Control of Altitude in Flying Drosophila
Unlike creatures that walk, flying animals need to control their horizontal motion as well as their height above the ground. Research on insects, the first animals to evolve flight, has revealed several visual reflexes that are used to govern horizontal course. For example, insects orient toward prominent vertical features in their environment [1], [2], [3], [4] and [5] and generate compensatory reactions to both rotations [6] and [7] and translations [1], [8], [9], [10] and [11] of the visual world. Insects also avoid impending collisions by veering away from visual expansion [9], [12], [13] and [14]. In contrast to this extensive understanding of the visual reflexes that regulate horizontal course, the sensory-motor mechanisms that animals use to control altitude are poorly understood. Using a 3D virtual reality environment, we found that Drosophila utilize three reflexesâedge tracking, wide-field stabilization, and expansion avoidanceâto control altitude. By implementing a dynamic visual clamp, we found that flies do not regulate altitude by maintaining a fixed value of optic flow beneath them, as suggested by a recent model [15]. The results identify a means by which insects determine their absolute height above the ground and uncover a remarkable correspondence between the sensory-motor algorithms used to regulate motion in the horizontal and vertical domains
Experimental application of sum rules for electron energy loss magnetic chiral dichroism
We present a derivation of the orbital and spin sum rules for magnetic
circular dichroic spectra measured by electron energy loss spectroscopy in a
transmission electron microscope. These sum rules are obtained from the
differential cross section calculated for symmetric positions in the
diffraction pattern. Orbital and spin magnetic moments are expressed explicitly
in terms of experimental spectra and dynamical diffraction coefficients. We
estimate the ratio of spin to orbital magnetic moments and discuss first
experimental results for the Fe L_{2,3} edge.Comment: 11 pages, 2 figure
A novel index in healthy infants and children â subarachnoid space: ventricle ratio
Background: The subarachnoid space (SAS) and ventricular width (VW) in normalinfants and children were studied with ultrasonography to provide the objectivemeasurement and define a normal range for these measurements. The additional aim was to determine the stable ratio as a SAS/VW.Materials and methods: A total of 100 healthy subjects, including 48 males and52 females, were studied. The cases were divided into 3 age groups: 0â6 months(n = 65), 7â12 months (n = 24) and > 13 months (n = 11). Transfontanel ultrasonography was performed in all the cases. SAS, VW and the SAS/VW ratios were calculated. The study was approved by the ethical committee. All parents wereinformed about the sonographic examination and their approvals were taken.Results: SAS was calculated as 3.1 (0.5â6) mm and VW was calculated as 3.6(1.3â5) mm. SAS/VW ratio was 0.9 ± 0.3. There was no statistically significant difference among SAS, VW and SAS/VW ratios in 3â97 percentile group (p > 0.05).Conclusions: Ultrasonography can be used as a practicable and reproducible modalityin the measurement of SAS and VW in healthy children. It is a non-invasivemethod and allows for serial follow-up. SAS/VW ratio can be used as an index inhealthy children
KEBUTUHAN PRASARANA DAN SARANA DI PULAU MANTEHAGE
Pulau Mantehage merupakan salah satau pulau yang berada di Kecamatan Wori Kabupaten Minahasa Utara. Secara geografis Pulau Mantehage terletak disebelah utara dari ujung Pulau Sulawesi pada posisi 124 0 45â 20ââ BT 1Ë 42â 56ââ LU, dengan luas Pulau Mantehage 18,56 km2 dan dikelilingi hutan mangrove. Kondisi infrastruktur di Pulau Mantehage perlu untuk mendukung ketersediaan prasarana dan sarana serta pelayanannya terhadap masyarakat di Pulau Mantehage. Tujuan penelitian ini adalah mengindentifikasi persebaran dan kondisi eksisting prasarana dan sarana di Pulau Mantehage dan menganalisis kebutuhan prasarana dan sarana serta pelayanannya di Pulau Mantehage berdasarkan proyeksi 5 tahun yang akan datang. Metode yang digunakan dalam penelitian ini adalah metode penelitian deskriptif kualitatif dan analisa menggunakan pendekatan kuantitatif, karena dalam  pelaksanaannya meliputi data, analisis dan interpretasi. Berdasarkan hasil penelitian ini menunjukkan bahwa ketersediaan infrastruktur di Pulau Mantehage belum memadai dan ada juga yang memadai. Infrastruktur yang memadai yaitu infrastruktur hijau, fasilitas umum, fasilitas sosial dan infrastruktur transportasi dan mobilisasi, sedangkan infrastruktur yang belum memadai yaitu infrastruktur jalan karena perlu adanya peningkatan kualitas jalan di beberapa titik ruas jalan akibat kerusakan material perkerasan, infrastruktur drainase belum memadai karena ada beberapa titik ruas jalan yang tidak terdapat drainase sehingga perlu adanya pembuatan drainase baru agar dapat menampung debit air hujan. Infrastruktur air bersih belum memadai karena beberapa titik lokasi sumber mata air mengandung air payau, masyarakat Pulau Mantehage menggunakan air bersih bersumber dari air hujan sehingga perlu dilakukan prediksi berupa proyeksi 5 tahun kedepan (tahun 2020) namun untuk 5 tahun kedepan mungkin bisa telayani namun ketersediaan debit sumber mata air belum perlu dapat melayani masyarakat di tahun 2020. Infrstruktur persampahan di Pulau Mantehage secara umum masih di bakar tapi untuk kedepannya perlu disediakan mesin pembakar sampah. Infrsatruktur telekomunikasi perlu penyediaan tower BTS menara telekomunikasi sebagai solusi layanan komunikasi dan informasi di daerah terpencil seperti pedesaan dan pulau-pulau. Infrastruktur listrik di Pulau Matehage bersumber dari PLN sehingga perlu adanya penambahan pasokan listrik seperti Pembangkit Listrik Tenaga Surya (Solar Cell) di Pulau Mantehage. Kata Kunci : Infrastruktur, Pulau Mantehag
Determination of the branching ratios and
Improved branching ratios were measured for the decay in a
neutral beam at the CERN SPS with the NA31 detector: and .
From the first number an upper limit for and transitions in neutral kaon decay is derived. Using older results for the
Ke3/K3 fraction, the 3 branching ratio is found to be , about a factor three more
precise than from previous experiments
Metastatic Serous Carcinoma Initially Presented As An Incarcerated And Strangulated Umbilical Hernia: A Rare Case Report
Introduction: We report a rare case of a metastatic serous ovarian carcinoma presented as an incarcerated and strangulated umbilical hernia.Presentation of case: A 54 year-old female was admitted to the hospital with a painful mass around the umblical region. It was elucidated during clinical history that the mass had been present for 3 to 4 years without pain. An incarcerated and strangulated umbilical hernia including a solid mass and mesenteric fat was detected on physical examination. She underwent an urgent operation for strangulated umbilical hernia. The pathological diagnosis of the hernia material was reported as carcinoma compatible with serous ovarian carcinoma metastasis. Concurrently, total abdominal histerectomy and bilateral salphingo-oopherectomy, pelvic and paraaortic lymph node dissection, omentectomy and sigmoid colon resection were performed. Histopathological evaluation confirmed the serous carcinoma originated from the left ovary.Conclusion: In the literature, some metastatic tumors have been reported to be presented as umbilical metastasis rarely. However, the present case is the first metastatic ovarian cancer that initially presented as an incarcerated and strangulated umbilical hernia in the literature, to the best of our knowledge.Â
Ab initio study of bilateral doping within the MoS2-NbS2 system
We present a systematic study on the stability and the structural and
electronic properties of mixed molybdenum-niobium disulphides. Using density
functional theory we investigate bilateral doping with up to 25 % of MoS2
(NbS2) by Nb (Mo) atoms, focusing on the precise arrangement of dopants within
the host lattices. We find that over the whole range of considered
concentrations, Nb doping of MoS2 occurs through a substitutional mechanism.
For Mo in NbS2 both interstitial and substitutional doping can co-exist,
depending upon the particular synthesis conditions. The analysis of the
structural and electronic modifications of the perfect bulk systems due to the
doping is presented. We show that substitutional Nb atoms introduce electron
holes to the MoS2, leading to a semiconductor-metal transition. On the other
hand, the Mo doping of Nb2, does not alter the metallic behavior of the initial
system. The results of the present study are compared with available
experimental data on mixed MoS2-NbS2 (bulk and nanoparticles).Comment: 7 pages, 6 figure
Measurement of Neutrino-Electron Scattering Cross-Section with a CsI(Tl) Scintillating Crystal Array at the Kuo-Sheng Nuclear Power Reactor
The elastic scattering cross-section was measured with
a CsI(Tl) scintillating crystal array having a total mass of 187kg. The
detector was exposed to an average reactor flux of
at the Kuo-Sheng Nuclear Power
Station. The experimental design, conceptual merits, detector hardware, data
analysis and background understanding of the experiment are presented. Using
29882/7369 kg-days of Reactor ON/OFF data, the Standard Model(SM) electroweak
interaction was probed at the squared 4-momentum transfer range of . The ratio of experimental to SM cross-sections
of was measured. Constraints on
the electroweak parameters were placed, corresponding to a weak
mixing angle measurement of \s2tw = 0.251 \pm 0.031({\it stat}) \pm
0.024({\it sys}) . Destructive interference in the SM \nuebar -e process was
verified. Bounds on anomalous neutrino electromagnetic properties were placed:
neutrino magnetic moment at \mu_{\nuebar}< 2.2 \times 10^{-10} \mu_{\rm B}
and the neutrino charge radius at -2.1 \times 10^{-32} ~{\rm cm^{2}} <
\nuchrad < 3.3 \times 10^{-32} ~{\rm cm^{2}}, both at 90% confidence level.Comment: 18 Figures, 7 Tables; published version as V2 with minor revision
from V
Potential use of pepper waste and microalgae Spirulina sp. for bioelectricity generation
The research aimed to generate bioelectricity using pepper waste and the microalgae Spirulina sp by a double-chamber microbial fuel cell (dcMFC). A dcMFC was constructed with Cu and Zn electrodes, where organic waste and microalgae were placed in the anodic and cathodic chambers, respectively. Also, electrochemical parameters were measured for 35 days. Finally, possible electrogenic microorganisms were isolated and identified. It was possible to generate maximum values of current (6.04414 ± 0.2145 mA) and voltage (0.77328 ± 0.213 V). The maximum conductivity value was 134.1636 ± 7.121 mS/cm, while the internal resistance value was 83.784
. The values of power and current density reached were 584.45 ± 19.14 mW/cm 2 and 5.983 A/cm 2, respectively. The optimal operating pH was 4.59 ± 0.14. From the microbial growth on the anode, the yeast Yarrowia phangngaensis (1) and Pseudomonas stutzeri (2) were identified, which may be involved in the transfer of electrons to the electrode. In conclusion, it was possible to generate clean energy in a laboratory-scale dcMFC when pepper waste and Spirulina sp. were used. These results are promising because organic waste can generate sustainable and environmentally friendly energy
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