840 research outputs found

    Observation bias: The impact of demand censoring on newsvendor level and adjustment behavior

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    In an experimental newsvendor setting we investigate three phenomena: Level behavior ? the decision-maker's average ordering tendency; adjustment behavior ? the tendency to adjust period-to-period order quantities; and observation bias ? the tendency to let the degree of demand feedback influence order quantities. We find that the portion of mismatch cost due to adjustment behavior exceeds the portion of mismatch cost due to level behavior in three out of four conditions. Observation bias is studied through censored demand feedback, a situation which arguably represents the majority of newsvendor settings. When demands are uncensored, subjects tend to order below the normative quantity when facing high margin and above the normative quantity when facing low margin, but in neither case beyond mean demand (a.k.a. the pull-to-center effect). Censoring in general leads to lower quantities, magnifying the below-normative level behavior when facing high margin but partially counterbalancing the above-normative level behavior when facing low margin, violating the pull-to-center effect in both cases.

    Charge regulation: a generalized boundary condition?

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    The three most commonly-used boundary conditions for charged colloidal systems are constant charge (insulator), constant potential (conducting electrode) and charge regulation (ionizable groups at the surface). It is usually believed that the charge regulation is a generalized boundary condition that reduces in some specific limits to either constant charge or constant potential boundary conditions. By computing the disjoining pressure between two symmetric planes for these three boundary conditions, both numerically (for all inter-plate separations) and analytically (for small inter-plate separations), we show that this is not, in general, the case. In fact, the limit of charge regulation is a separate boundary condition, yielding a disjoining pressure with a different characteristic separation-scaling. Our findings are supported by several examples demonstrating that the disjoining pressure at small separations for the charge regulation boundary-condition depends on the details of the dissociation/association process.Comment: 6 pages, 3 figure

    Charged Membranes: Poisson-Boltzmann theory, DLVO paradigm and beyond

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    In this chapter we review the electrostatic properties of charged membranes in aqueous solutions, with or without added salt, employing simple physical models. The equilibrium ionic profiles close to the membrane are governed by the well-known Poisson-Boltzmann (PB) equation. We analyze the effect of different boundary conditions, imposed by the membrane, on the ionic profiles and the corresponding osmotic pressure. The discussion is separated into the single membrane case and that of two interacting membranes. For one membrane setup, we show the different solutions of the PB equation and discuss the interplay between constant-charge and constant-potential boundary conditions. A modification of the PB theory is presented to treat the extremely high counter-ion concentration in the vicinity of a charge membrane. For two equally-charged membranes, we analyze the different pressure regimes for the constant-charge boundary condition, and discuss the difference in the osmotic pressure for various boundary conditions. The non-equal charged membranes is reviewed as well, and the crossover from repulsion to attraction is calculated analytically. We then examine the charge-regulation boundary condition and discuss its effects on the ionic profiles and the osmotic pressure for two equally-charged membranes. In the last section, we briefly review the van der Waals (vdW) interactions and their effect on the free energy between two planar membranes. We explain the simple Hamaker pair-wise summation procedure, and introduce the more rigorous Lifshitz theory. The latter is a key ingredient in the DLVO theory, which combines repulsive electrostatic with attractive vdW interactions, and offers a simple explanation for colloidal or membrane stability. Finally, the chapter ends by a short account of the limitations of the approximations inherent in the PB theory.Comment: 57 pages, 19 figures, From the forthcoming Handbook of Lipid Membranes: Molecular, Functional, and Materials Aspects. Edited by Cyrus Safinya and Joachim Radler, Taylor & Francis/CRC Press, 201

    Surface Tension of Electrolyte Solutions: A Self-consistent Theory

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    We study the surface tension of electrolyte solutions at the air/water and oil/water interfaces. Employing field-theoretical methods and considering short-range interactions of anions with the surface, we expand the Helmholtz free energy to first-order in a loop expansion and calculate the excess surface tension. Our approach is self-consistent and yields an analytical prediction that reunites the Onsager-Samaras pioneering result (which does not agree with experimental data), with the ionic specificity of the Hofmeister series. We obtain analytically the surface-tension dependence on the ionic strength, ionic size and ion-surface interaction, and show consequently that the Onsager-Samaras result is consistent with the one-loop correction beyond the mean-field result. Our theory fits well a wide range of concentrations for different salts using one fit parameter, reproducing the reverse Hofmeister series for anions at the air/water and oil/water interfaces.10.1029Comment: 5 pages, 2 figure

    Complex Fluids with Mobile Charge-Regulated Macro-Ions

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    We generalize the concept of charge regulation of ionic solutions, and apply it to complex fluids with mobile macro-ions having internal non-electrostatic degrees of freedom. The suggested framework provides a convenient tool for investigating systems where mobile macro-ions can self-regulate their charge (e.g., proteins). We show that even within a simplified charge-regulation model, the charge dissociation equilibrium results in different and notable properties. Consequences of the charge regulation include a positional dependence of the effective charge of the macro-ions, a non-monotonic dependence of the effective Debye screening length on the concentration of the monovalent salt, a modification of the electric double-layer structure, and buffering by the macro-ions of the background electrolyte.Comment: 7 pages, 5 figure

    La casa Trinseria de Cassà de la Selva

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    Implementasi Kebijakan Fiskal: Pembiayaan Program Pembangunan Berbasis Rukun Tetangga (Pbrt) di Kabupaten Sumbawa Barat

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    Fiscal policy is one form of economic policies pursued in the context of macroeco-nomic stabilization, promote growth, equity, and sustainability menjega budget. WestSumbawa regency is one of regencies in NTB province has embarked on one of fiscalpolicy implementation is in the financing of Neighborhood-Based Development pro-gram (PBRT). PBRT program is a strategy of development by putting the region atthe lowest level of development of the neighborhood (RT). This policy is the empow-erment of RT with the understanding that the RT is not the lowest governmentalstructures and nongovernmental organizations that are able to understand all the com-plaints and needs of their citizens. RT becomes a very important institution in whichis located all the pecking order and also serves as a populist economic base which isthen defined as the Regulation (Regulation No. 27 Year 2008 regarding PBRT). Thispaper reviewed the implementation of the program PBRT is related to how big thebudget from the budget for financing. Furthermore, by using Regulatory Impact Analysiswill be analyzed whether the policy PBRT program will bring net benefits to societyand increase welfare in West Sumbawa regency

    Cardiovascular-Related Death Risk Factors in Hypertensive Patients: Indonesia Family Life Survey 2000-2014

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    Objective: To determine the characteristics of the risk factors of cardiovascular death in hypertensive patients in Indonesia based on the Indonesian Family Life Survey (IFLS) longitudinal data.                                  Methods: This was a retrospective descriptive study on secondary data from the IFLS population starting from2000 and was followed up in 2007 and 2014. The inclusion criteria for participation were15 years old or older, had hypertension, had cardiovascular events as thecause of death, and had complete data in both IFLS 3 (2000) and IFLS 4 (2007).Results: The IFLS 5 (2014) reported 918 deaths among eligible subjects  with complete data, both in IFLS 3 (2000) and IFLS 4 (2007). Of those, a total of 608 subjects experienced hypertension started from 2000 and/or 2007. Of these deaths, 112 were due to cardiovascular events. Cardiovascular death was more common in males (58.9%), age of >65 years old  when died (47.3%), had poor socioeconomic status (24.1%), and with normal body mass index (54.9%).Conclusion: Male, late adulthood, low level of education, normal BMI, and poor socioeconomic status represented the greater risks of cardiovascular death among hypertensive patients in Indonesia.
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