6,290 research outputs found

    Correlation of the Hippocampal theta rhythm to changes in hypothalamic temperature

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    Warming and cooling the preoptic anterior hypothalamic area in awake, loosely restrained rabbits was found to evoke theta rhythm. This is consistent with previous studies indicating that theta rhythm is a nonspecific response evoked by stimulation of several sensory modalities. Several studies have correlated theta rhythm with alertness. A neural pathway involving the hypothalamus, the hippocampus, the septal area, and the reticular formation is proposed. Thus, a role of this pathway may be to alert the animal to changes in its body temperature

    To make a nanomechanical Schr\"{o}dinger-cat mew

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    By an explicite calculation of Michelson interferometric output intensities in the optomechanical scheme proposed by Marshall et al. (2003), an oscillatory factor is obtained that may go down to zero just at the time a visibility revival ought to be observed. Including a properly tuned phase shifter offers a simple amendment to the situation. By using a Pockels phase shifter with fast time-dependent modulation in one arm, one may obtain further possibilities to enrich the quantum state preparation and reconstruction abilities of the original scheme, thereby improving the chances to reliably detect genuine quantum behaviour of a nanomechanical oscillator.Comment: For Proc. DICE-2010 (Castiglioncello), to be published in J. Phys. Conf. Ser., 201

    Impact-ionization and noise characteristics of thin III-V avalanche photodiodes

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    It is, by now, well known that McIntyre\u27s localized carrier-multiplication theory cannot explain the suppression of excess noise factor observed in avalanche photodiodes (APDs) that make use of thin multiplication regions. We demonstrate that a carrier multiplication model that incorporates the effects of dead space, as developed earlier by Hayat et al. provides excellent agreement with the impact-ionization and noise characteristics of thin InP, In/sub 0.52/Al/sub 0.48/As, GaAs, and Al/sub 0.2/Ga/sub 0.8/As APDs, with multiplication regions of different widths. We outline a general technique that facilitates the calculation of ionization coefficients for carriers that have traveled a distance exceeding the dead space (enabled carriers), directly from experimental excess-noise-factor data. These coefficients depend on the electric field in exponential fashion and are independent of multiplication width, as expected on physical grounds. The procedure for obtaining the ionization coefficients is used in conjunction with the dead-space-multiplication theory (DSMT) to predict excess noise factor versus mean-gain curves that are in excellent accord with experimental data for thin III-V APDs, for all multiplication-region widths

    Electronic transport in a Cantor stub waveguide network

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    We investigate theoretically, the character of electronic eigenstates and transmission properties of a one dimensional array of stubs with Cantor geometry. Within the framework of real space re-normalization group (RSRG) and transfer matrix methods we analyze the resonant transmission and extended wave-functions in a Cantor array of stubs, which lack translational order. Apart from resonant states with high transmittance we unravel a whole family of wave-functions supported by such an array clamped between two-infinite ordered leads, which have an extended character in the RSRG scheme, but, for such states the transmission coefficient across the lead-sample-lead structure decays following a power-law as the system grows in size. This feature is explained from renormalization group ideas and may lead to the possibility of trapping of electronic, optical or acoustic waves in such hierarchical geometries

    Word embeddings for practical information retrieval

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    We assess the suitability of word embeddings for practical information retrieval scenarios. Thus, we assume that users issue ad-hoc short queries where we return the first twenty retrieved documents after applying a boolean matching operation between the query and the documents. We compare the performance of several techniques that leverage word embeddings in the retrieval models to compute the similarity between the query and the documents, namely word centroid similarity, paragraph vectors, Word Mover’s distance, as well as our novel inverse document frequency (IDF) re-weighted word centroid similarity. We evaluate the performance using the ranking metrics mean average precision, mean reciprocal rank, and normalized discounted cumulative gain. Additionally, we inspect the retrieval models’ sensitivity to document length by using either only the title or the full-text of the documents for the retrieval task. We conclude that word centroid similarity is the best competitor to state-of-the-art retrieval models. It can be further improved by re-weighting the word frequencies with IDF before aggregating the respective word vectors of the embedding. The proposed cosine similarity of IDF re-weighted word vectors is competitive to the TF-IDF baseline and even outperforms it in case of the news domain with a relative percentage of 15%

    Awareness and prevalence of industrialized building system (IBS) in Iran

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    The introduction of modern technologies and development of building systems has influenced a fundamental transformation in many aspects of construction industry. However, still in major parts of building projects, conventional methods are being used in Iran. Traditional methods cause many problems such as project prolongation, low economic efficiency, too much stuff, and low quality of products. These shortcomings are more tangible in large-scale housing projects that require a vast domain of constructions; therefore, transformation from the current conventional building systems to the industrialized building systems (IBS) is needed more than ever. In order to this transformation it is vital that first the perceptions of the industry on these issues are adequately studied in this research. According to the lack of strategic plans and effective measures to promote IBS at country level, in addition to introducing the level of awareness and familiarity to IBS technical knowledge, the prevalence of both IBS components implementation and using IBS in different type of projects in Iran conducted. A Likert based questionnaire was designed according to the level of awareness and the prevalence of IBS was evaluated applying the mean index and average ranking method. Consistent with this study, only 2% of respondents are fully familiar with IBS and approximately 95% of respondents does not have acceptable awareness of this construction method. The average index of prefabricated components prevalence in Iran is 2.72 and sandwich panel is the most prevalent IBS components by mean index of 3.42. In other side, the estimation of the mean index of IBS method prevalence in different types of projects in Iran is 2.69 and marine structures are the most prevalent project type that is performed using IBS with the mean index of 3.89. Accordingly, the results indicate that the prevalence of IBS in terms of components and types of projects is not at significant level. This research examines the key suggestions to encourage IBS usage in Iran and the mandatory use of prefabricated systems by government is the best solution for IBS promotion by mean index of 3.96. This paper provides an overview of IBS current state in Iran. Clearly, this awareness will prompt construction industry practitioners to a deeper exchange of ideas and promoting IBS in the future

    Signal-to-noise ratio of Gaussian-state ghost imaging

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    The signal-to-noise ratios (SNRs) of three Gaussian-state ghost imaging configurations--distinguished by the nature of their light sources--are derived. Two use classical-state light, specifically a joint signal-reference field state that has either the maximum phase-insensitive or the maximum phase-sensitive cross correlation consistent with having a proper PP representation. The third uses nonclassical light, in particular an entangled signal-reference field state with the maximum phase-sensitive cross correlation permitted by quantum mechanics. Analytic SNR expressions are developed for the near-field and far-field regimes, within which simple asymptotic approximations are presented for low-brightness and high-brightness sources. A high-brightness thermal-state (classical phase-insensitive state) source will typically achieve a higher SNR than a biphoton-state (low-brightness, low-flux limit of the entangled-state) source, when all other system parameters are equal for the two systems. With high efficiency photon-number resolving detectors, a low-brightness, high-flux entangled-state source may achieve a higher SNR than that obtained with a high-brightness thermal-state source.Comment: 12 pages, 4 figures. This version incorporates additional references and a new analysis of the nonclassical case that, for the first time, includes the complete transition to the classical signal-to-noise ratio asymptote at high source brightnes

    Dietary alterations modulate the microRNA 29/30 and IGF-1/AKT signaling axis in breast Cancer liver metastasis.

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    Background: Metastatic cancer is incurable and understanding the molecular underpinnings is crucial to improving survival for our patients. The IGF-1/Akt signaling pathway is often impaired in cancer leading to its progression and metastases. Diet modification is known to alter the IGF-1/Akt pathway and affect the expression of microRNA involved in tumor initiation, growth and metastases. Liver metastases are one of the most common type of metastases in breast and colon cancer. In the present study, we looked at the effect of diet modification on the expression of microRNA in normal liver and liver with breast cancer metastases using in vivo model. Methodology: 6-month-old C57BL/6 J mice were put on either an ad libitum (AL) diet, or 40% calorie restricted (CR) diet or were fasted for 24 h (FA) before sacrifice. MicroRNA array analysis, western blot and qRT-PCR were performed using liver tissue to compare the treatment groups. A breast cancer model was also used to study the changes in microRNA expression in liver of a group of BALB/c mice orthotopically injected with 4 T1 cells in the mammary fat pad, put on either an AL or 30% CR diet. Liver and primary tumor tissues were used to perform qRT-PCR to compare the treatment groups. Results: MicroRNA array analysis showed significant changes in miRNA expression in both CR and FA conditions in normal liver. Expression of miR-29 and miR-30 family members was increased in both CR and FA. Western blot analysis of the normal liver tissue showed that CR and FA downregulated the IGF-1/Akt pathway and qRT-PCR showed that the expression of miR-29b, miR-29c, miR-30a and miR-30b were increased with CR and FA. Liver tissue collected from mice in the breast cancer model showed an increase in expression of miR-29b, miR-29c and miR-30b while tumor tissue showed increased expression of miR-29c, miR-30a and miR-30b. Discussion: Members of the miR-29 family are known to target and suppress IGF-1, while members of the miR-30 family are known to target and suppress both IGF-1 and IGF-1R. In the present study, we observe that calorie restriction increased the expression of miR-29 and miR-30 in both the normal liver as well as the liver with breast cancer metastases. These findings suggest that dietary alterations may play a role in the treatment of liver metastasis, which should be evaluated further

    Perbandingan Efektivitas Media Cetak (Folder dan Poster-Kalender) dan Penyajian Tanaman Zodia terhadap Peningkatan Pengetahuan Masyarakat

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    Objectives of research were to determine the combination treatment of printed material (folder media and calendarposter)combined with Zodia plant toward increasing community knowledge in North Bogor sub-district. Design ofresearch was a quasi-experimental design. Sample was chosen in the endemic area of dengue disease (DBD).Sampling design was a separate sample pretest-posttest control group design. Experimental design was a 2x3factorial design. Respondents were totally 90 housewives, divided into six groups. Research result was: (1)effectiveness of printed media can be increased toward phisical media USAge; (2) increasing knowledge was veryeffective toward media combination; (3) folder combined with Zodia plant was more effective to increase communityknowledge; Community knowledge was emphasis on utilizing Zodia plant to prevent mosquito as an agent of denguedisease; (4) several characteristic factors were increase community knowledge effectively, (5) innovation factorswere also effectively increase community knowledge. It was concluded that folder media combined with Zodia wasthe most effective media to deliver a message of Zodia plant to increase community knowledge
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