37,736 research outputs found
Open String Creation by S-Branes
An sp-brane can be viewed as the creation and decay of an unstable
D(p+1)-brane. It is argued that the decaying half of an sp-brane can be
described by a variant of boundary Liouville theory. The pair creation of open
strings by a decaying s-brane is studied in the minisuperspace approximation to
the Liouville theory. In this approximation a Hagedorn-like divergence is found
in the pair creation rate, suggesting the s-brane energy is rapidly transferred
into closed string radiation.Comment: Talk presented at the Hangzhou String 2002 Conference, August 12-1
Rotational perturbations in Neveu-SchwarzâNeveu-Schwarz string cosmology
First order rotational perturbations of the flat Friedmann-Robertson-Walker metric are considered in the framework of four dimensional Neveu-SchwarzâNeveu-Schwarz string cosmological models coupled with dilaton and axion fields. For the H field we use the solitonic ansatz, assuming that it is a function of time only. The decay rate of rotation depends mainly upon the dilaton field potential U. The equation for rotation imposes strong limitations upon the functional form of U, restricting the allowed potentials to two: the trivial case U=0 and a generalized exponential type potential. In these two models the metric rotation function can be obtained in an exact analytic form in both Einstein and string frames. In the potential-free case the decay of rotational perturbations is governed by an arbitrary function of time while in the presence of a potential the rotation tends rapidly to zero in both Einstein and string frames.published_or_final_versio
Demonstration of astrocytes in cultured amniotic fluid cells of three cases with neural-tube defect
We have investigated the origin of rapidly adhering (RA) cells in three cases of neural tube defects (two anencephali, one encephalocele). We were able to demonstrate the presence of glial fibrillary acidic (GFA) protein in variable percentages (4â80%) of RA cells cultured for 4â6 days by use of indirect immunofluorescence with GFA antiserum. Cells cultured from amniotic fluids of normal pregnancies and fetal fibroblasts were completely GFA protein negative. GFA protein is well established as a highly specific marker for astrocytes. Demonstration of astrocytes may prove to be a criterion of high diagnostic value for neural tube defects. The percentage of astrocytes decreased with increasing culture time, while the percentage of fibronectin positive cells increased both in amniotic fluid cell cultures from neural tube defects and normal pregnancies
Design of a highly-birefringent microstructured photonic crystal fiber for pressure monitoring
We present the design of an air hole microstructured photonic crystal fiber for pressure sensing applications. The air-hole photonic crystal lattices were designed to produce a large intrinsic birefringence of 1.16x10-3. The impact of the surrounding air holes for pressure sensing to the propagation mode profiles and indices were studied and improved, which ensures single mode propagation in the fiber core defined by the photonic crystal lattice. An air hole matrix and a practical chemical etching process during the fiber perform preparation stage is proposed to produce an optical fiber with a birefringence-pressure coefficient of 43.89Ă10-6MPa-1 or a fiber Bragg grating pressure responsivity of 44.15 pm/MPa, which is a 17 times improvement over previous photonic crystal fiber designs. Š 2010 Optical Society of America
Cross-National Study of Young Female Consumer Behaviour, Innovativeness and Apparel Evaluation: China and India
In order to advance our knowledge about consumersâ shopping behaviour and preferences in two emerging markets (China and India), the current study was undertaken to investigate (1) apparel consumersâ shopping behaviour; (2) the effect of consumer innovativeness, and (3) the salient impact of apparel evaluative cues. An online self-administered survey consisted of shopping behavioural questions, the Domain Specific Innovativeness (DSI) scale, twelve apparel cues, and demographic questions were used for this study. In total, 266 and 236 usable data were collected from Chinese and Indian female participants respectively. The findings indicated that Chinese and Indian fashion innovators tended to spend more money on new clothes than non-innovators. Chinese fashion innovators spent significantly more time shopping online than did Indian innovators. In terms of the importance of evaluative cues, fashion innovators and non-innovators in both countries considered fit to be the most important cue; style, colour, and comfort played a relatively important role in clothing evaluation as well, but ease of care and durability were cited as relatively less important among many other cues. The two least important cues were brand name and country of origin
Iron-Catalyzed Nitrene Insertion Reaction for Facile Construction of Amide Compounds
A facile method for the construction of amide compounds from aldehydes by an iron-catalyzed nitrene insertion reaction has been developed. Both aryl and aliphatic aldehydes can directly afford the corresponding amides with an iron(II)-terpyridine (tpy) complex formed in situ as catalyst, and PhI=NTs as nitrogen source under mild reaction conditions. An ESI-MS study revealed the formation of [Fe(tpy)NTs)]+ as a reaction intermediate. Š Georg Thieme Verlag Stuttgart - New York.postprin
Optically and electrically tunable graphene quantum dotâpolyaniline composite films
Graphene quantum dot-polyaniline (PANI-GQD) composite films were synthesized by a chemical oxidation polymerization process. The optical properties of the PANI-GQD composite were studied by varying the mole concentration of PANI and the size of the GQDs. The Au/PANI-GQDs/ITO sandwich device was fabricated in order to investigate the transport properties of the composite. A stable hysteresis loop was observed in response to the applied voltage. By varying the PANI content and size of the GQDs, the area within the hysteresis loop and electrical conductance behavior of the device can be tuned in a controlled manner. Both the tunable luminescence and electrical hysteresis behavior are attributed to surface states of the GQDs. The PANI-GQD composite films are expected to find application in photonic devices.Department of Applied Physic
Lived experience of Indonesian nurses in Japan: A phenomenological study
Aim: The movement of Indonesian nurses via a bilateral agreement with Japan has led to a substantial number of migrants to work as nurses in that nationâs healthcare system. The purpose of this research was to develop a deeper understanding of the meaningful experiences of Indonesian nurses while working in Japanese hospitals. Methods: In this phenomenological study, sampling was purposive and was based on information shared by five Indonesian nurses. The data were collected in interviews; the analysis was thematic.
Results: Six key themes were identified: (i) seeking better than before; (ii) communication challenges; (iii) the
nursing examination as a culmination; (iv) differences in nursing practice; (v) cultural differences; and (vi)
the benefits of living in developed country. Among these challenges, communication as the basis of shared
meaning and understanding was viewed as a complex issue, by both patients and coworkers. Conclusion: The results of this study call for further intervention in supporting Indonesian nurses living in Japan in their struggle with the issue of communication. The emphasis on language acquisition for personal and professional objectives, and the bridging of cultural differences as well, should be considered in an
international context
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Unusual Formation of Point-Defect Complexes in the Ultrawide-Band-Gap Semiconductor β-Ga2 O3
Understanding the unique properties of ultra-wide band gap semiconductors requires detailed information about the exact nature of point defects and their role in determining the properties. Here, we report the first direct microscopic observation of an unusual formation of point defect complexes within the atomic-scale structure of β-Ga2O3 using high resolution scanning transmission electron microscopy (STEM). Each complex involves one cation interstitial atom paired with two cation vacancies. These divacancy-interstitial complexes correlate directly with structures obtained by density functional theory, which predicts them to be compensating acceptors in β-Ga2O3. This prediction is confirmed by a comparison between STEM data and deep level optical spectroscopy results, which reveals that these complexes correspond to a deep trap within the band gap, and that the development of the complexes is facilitated by Sn doping through increased vacancy concentration. These findings provide new insight on this emerging material's unique response to the incorporation of impurities that can critically influence their properties
CDK1-PDK1-PI3K/Akt signaling pathway regulates embryonic and induced pluripotency
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