1,913 research outputs found

    A fundamental limit on the performance of geometrically-tuned planar resonators

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    Wigner-Crystal Formulation of Strong-Coupling Theory for Counter-ions Near Planar Charged Interfaces

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    We present a new analytical approach to the strong electrostatic coupling regime (SC), that can be achieved equivalently at low temperatures, high charges, low dielectric permittivity etc. Two geometries are analyzed in detail: one charged wall first, and then, two parallel walls at small distances, that can be likely or oppositely charged. In all cases, one type of mobile counter-ions only is present, and ensures electroneutrality (salt free case). The method is based on a systematic expansion around the ground state formed by the two-dimensional Wigner crystal(s) of counter-ions at the plate(s). The leading SC order stems from a single-particle theory, and coincides with the virial SC approach that has been much studied in the last 10 years. The first correction has the functional form of the virial SC prediction, but the prefactor is different. The present theory is free of divergences and the obtained results, both for symmetrically and asymmetrically charged plates, are in excellent agreement with available data of Monte-Carlo simulations under strong and intermediate Coulombic couplings. All results obtained represent relevant improvements over the virial SC estimates. The present SC theory starting from the Wigner crystal and therefore coined Wigner SC, sheds light on anomalous phenomena like the counter-ion mediated like-charge attraction, and the opposite-charge repulsion

    Effects of cryoprotectant concentration and cooling rate on vitrification of aqueous solutions

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    Vitrification of aqueous cryoprotectant mixtures is essential in cryopreservation of proteins and other biological samples. We report systematic measurements of critical cryoprotective agent (CPA) concentrations required for vitrification during plunge cooling from T=295 K to T=77 K in liquid nitrogen. Measurements on fourteen common CPAs including alcohols (glycerol, methanol, isopropanol), sugars (sucrose, xylitol, dextrose, trehalose), PEGs (ethylene glycol, PEG 200, PEG 2 000, PEG 20 000), glycols (DMSO, MPD), and salt (NaCl) were performed for volumes ranging over four orders of magnitude from ~nL to 20 mkL, and covering the range of interest in protein crystallography. X-ray diffraction measurements on aqueous glycerol mixtures confirm that the polycrystalline-to-vitreous transition occurs within a span of less than 2% w/v in CPA concentration, and that the form of polycrystalline ice (hexagonal or cubic) depends on CPA concentration and cooling rate. For most of the studied cryoprotectants, the critical concentration decreases strongly with volume in the range from ~5 mkL to ~0.1 mkL, typically by a factor of two. By combining measurements of the critical concentration versus volume with cooling time versus volume, we obtain the function of greatest intrinsic physical interest: the critical CPA concentration versus cooling rate during flash cooling. These results provide a basis for more rational design of cryoprotective protocols, and should yield insight into the physics of glass formation in aqueous mixtures.Comment: 8 pages, 6 jpg figure, 2 table

    ANALISIS PEMBANGUNAN BERKELANJUTAN PADA PERENCANAAN IBU KOTA NUSANTARA (IKN) (Studi Kasus di Kementerian Perencanaan Pembangunan Nasional/Badan Perencanaan Pembangunan Nasioanal)

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    This research aims to look at the development of the Nusantara Capital City (IKN) in realizing sustainable development in the aspect of environmental sustainability. The National Capital City "Nusantara" is considered an ideal city development that includes consideration of the principles of sustainable development including aspects of environmental sustainability, but from various previous studies, the policy of relocating the Indonesian Capital City only focuses on economic aspects, so this research examines the potential in more depth. moving the capital city of "Nusantara" to realize sustainable development using the development principles of the Bruntland Commission, namely environmental sustainability. The research method used is a qualitative method with a literature study approach. The data sources for this research come from primary data and secondary data. Meanwhile, data collection is carried out based on the documentation method through combining data or documents related to research. The results of the research show that the development of the Nusantara Capital City (IKN) in terms of environmental sustainability planning has included the concept of environmental sustainability, but in the early stages of IKN development it still does not have a significant impact on the environmental aspect. This can be seen from the four pillars of sustainable development in the environmental aspect which are detailed in more depth by Robinson et al (1990), which have not had a positive impact on the development of the capital city of the Indonesian, IKN. Therefore, it is hoped that IKN development will be more oriented or focused on development that guarantees environmental protection and all environmental elements to support the guarantee of current and future needs

    Statics and Dynamics of Strongly Charged Soft Matter

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    Soft matter materials, such as polymers, membranes, proteins, are often electrically charged. This makes them water soluble, which is of great importance in technological application and a prerequisite for biological function. We discuss a few static and dynamic systems that are dominated by charge effects. One class comprises complexation between oppositely charged objects, for example the adsorption of charged ions or charged polymers (such as DNA) on oppositely charged substrates of different geometry. The second class comprises effective interactions between similarly charged objects. Here the main theme is to understand the experimental finding that similarly and highly charged bodies attract each other in the presence of multi-valent counterions. This is demonstrated using field-theoretic arguments as well as Monte-Carlo simulations for the case of two homogeneously charged bodies. Realistic surfaces, on the other hand, are corrugated and also exhibit modulated charge distributions, which is important for static properties such as the counterion-density distribution, but has even more pronounced consequences for dynamic properties such as the counterion mobility. More pronounced dynamic effects are obtained with highly condensed charged systems in strong electric fields. Likewise, an electrostatically collapsed highly charged polymer is unfolded and oriented in strong electric fields. At the end of this review, we give a very brief account of the behavior of water at planar surfaces and demonstrate using ab-initio methods that specific interactions between oppositely charged groups cause ion-specific effects that have recently moved into the focus of interest.Comment: 61 pages, 31 figures, Physics Reports (2005)-in press (high quality figures available from authors

    Implementation of remote sensing for vegetation studying using vegetation indices and automatic feature space plot

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    Remote sensing techniques play an important role for monitoring vegetation growth and health, as well as others Landcover and Landuse. Image segmentation techniques are the most important tools, usually used to differentiate between the Earth’s surface features. One of the most common techniques to isolating the vegetated area from other land use regions is by utilizing the vegetation indices. In this research, different vegetation indices will be utilized for detecting and monitoring vegetation greenness, healthiness, and wetness. A new adaptive technique for image segmentation has been introduced in this research is automatic feature space plot, this based on partitioning the feature space plot between the visible Red and Near-Infrared remotely sensed bands. The multi temporal Enhanced-Thematic-Mapper plus (ETM+) available scenes have been used to cover the studied areas, in two successive years (2001 and 2002). This feature space plot segmentation method divided the reflectance diagram in two regions; these were vegetation and no-vegetation. A variety of indices formulas have also been used to globalize the vegetation patches, three of these vegetation indices have been adopted (i.e. RVI, NDVI and IPVI). The “NDVI” has higher recognized vegetated areas than other adopted indices of the amount of vegetation (ripe vegetation). Image binarization method being followed the implementation of the indices to isolating the vegetation areas from the image background. The isolated vegetated areas and their percentages are presented in tables to show the agriculture regions in two multi temporal scenes. The changes at these agriculture areas have also been computed and presented visually on the form of images, and numerically by listing them in tables (in km2). The counted areas resulted from the automatic feature space plot method and the isolated vegetated areas resulted from the implementation of the vegetation indices are also presented. Keyword Image segmentation, feature space plot segmentation, vegetation indices, image binarization, change detection technique

    Monte Carlo Simulation of Maxwell Molecule Interactions in Space Plasma

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    Electrostatic Disorder-Induced Interactions in Inhomogeneous Dielectrics

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    We investigate the effect of quenched surface charge disorder on electrostatic interactions between two charged surfaces in the presence of dielectric inhomogeneities and added salt. We show that in the linear weak-coupling regime (i.e., by including mean-field and Gaussian-fluctuations contributions), the image-charge effects lead to a non-zero disorder-induced interaction free energy between two surfaces of equal mean charge that can be repulsive or attractive depending on the dielectric mismatch across the bounding surfaces and the exact location of the disordered charge distribution.Comment: 7 pages, 2 figure

    Dates of birth and seasonal changes in well-being among 4904 subjects completing the seasonal pattern assessment questionnaire

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    Background: Abnormal distributions of birthdates, suggesting intrauterine aetiological factors, have been found in several psychiatric disorders, including one study of out-patients with Seasonal Affective Disorder (S.A.D.). We investigated birthdate distribution in relation to seasonal changes in well-being among a cohort who had completed the Seasonal Pattern Assessment Questionnaire (SPAQ). Method: A sample of 4904 subjects, aged 16 to 64, completed the SPAQ. 476 were cases of S.A.D. on the SPAQ and 580 were cases of sub-syndromal S.A.D. (S-S.A.D.). 92 were interview confirmed cases of S.A.D. Months and dates of birth were compared between S.A.D. cases and all others, between S.A.D. and S-S.A.D. cases combined and all others, and between interview confirmed cases and all others. Seasonality, as measured through seasonal fluctuations in well-being on the Global Seasonality Scores (GSS) of the SPAQ, was compared for all subjects by month and season of birth. Results: There was no evidence of an atypical pattern of birthdates for subjects fulfilling criteria for S.A.D., for the combined S.A.D. / S-S.A.D. group or for interview confirmed cases. There was also no relationship between seasonality on the GSS and month or season of birth. Limitations: Diagnoses of S.A.D. made by SPAQ criteria are likely to be overinclusive. Conclusion: Our findings differ from studies of patients with more severe mood disorders, including psychiatric out-patients with S.A.D. The lack of association between seasonality and birthdates in our study adds credence to the view that the aetiology of S.A.D. relates to separable factors predisposing to affective disorders and to seasonality
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