Hedonic Regressions and the Decomposition of a House Price index into Land and Structure Components

The paper uses hedonic regression techniques in order to decompose the price of a house into land and structure components using readily available real estate sales data for a Dutch city. In order to get sensible results, it was useful to use a nonlinear regression model using data that covered multiple time periods. It also proved to be necessary to impose some restrictions on the price of structures. The resulting builder’s hedonic regression model was compared with the results for traditional logarithmic hedonic regression models.House price indexes, land and structure components, time dummy hedonic regressions, Fisher ideal indexes.

The Decomposition of a House Price index into Land and Structures Components: A Hedonic Regression Approach

The paper uses hedonic regression techniques in order to decompose the price of a house into land and structure components using readily available real estate sales data for a Dutch city. In order to get sensible results, it proved necessary to use a nonlinear regression model using data that covered multiple time periods. It also proved to be necessary to impose some monotonicity restrictions on the price of land and structures. The results of the additive model were compared with the results of a traditional logarithmic hedonic regression model.Property price indexes, hedonic regressions, repeat sales method, rolling year indexes, Fisher ideal indexes.

Why network coherent data is smart

Voltage and current data time stamped within sufficient time-uncertainty allow smart opportunities in network operation. The usefulness of network coherent data is demonstrated by means of two case studies. It is shown that synchrophasors could further additional network performance information on renewable sources of energy integrated at distribution voltage levels. On-line modelling is an additional smart opportunity made possible by PQ instrumentation if designed according to the latest draft of the IEC 61000-4-30 Class requirements

A South African review of harmonic emission level assessment as per IEC61000-3-6

Large-scale renewable power producing plants are being integrated into South African networks. Network operators need to ensure that Renewable Power Plants (RPP) do not negatively affect the power quality levels of their networks, as harmonics amongst others could become a concern. IEC 61000-3-6 details a method for allocating voltage harmonic emission limits for distorting loads. This method works well for the allocation of emission limits; however it does not address the management of harmonic emissions once a plant is connected to the network. The management of harmonic emissions requires that network operators measure or quantify the emissions from loads and generators to determine compliance. Post-connection quantification of harmonic levels and compliance is a challenge for network operators. The question asked is “How should a network operator measure/quantify the harmonic emissions of a load/generator to establish compliance with the calculated limits as per IEC 61000-3-6”. This paper reviews within a South African context methods of assessing harmonic emission levels and then evaluates these methods by means of field data. Opportunities for improvement are identified and operational requirements discussed

Moving Beyond Traditional Null Hypothesis Testing: Evaluating Expectations Directly

This mini-review illustrates that testing the traditional null hypothesis is not always the appropriate strategy. Half in jest, we discuss Aristotle's scientific investigations into the shape of the earth in the context of evaluating the traditional null hypothesis. We conclude that Aristotle was actually interested in evaluating informative hypotheses. In contemporary science the situation is not much different. That is, many researchers have no particular interest in the traditional null hypothesis. More can be learned from data by evaluating specific expectations, or so-called informative hypotheses, than by testing the traditional null hypothesis. These informative hypotheses will be introduced while providing an overview of the literature on evaluating informative hypothesis

Neutrophil-endothelial interactions in respiratory syncytial virus bronchiolitis:An understudied aspect with a potential for prediction of severity of disease

Respiratory syncytial virus (RSV) lower respiratory tract infection (LRTI) causes significant morbidity and mortality among young infants worldwide. It is currently widely accepted that neutrophil influx into the airways is a hallmark of the pathophysiology. However, the exact mechanism of neutrophil migration from the vasculature into the alveolar space in RSV LRTI has received little attention. Data shows that endothelial cells become activated upon RSV infection, driving a 'pro-adhesive state' for circulating neutrophils with upregulation of endothelial intercellular adhesion molecule-1 (ICAM-1). During RSV LRTI different subsets of immature and mature neutrophils are present in the bloodstream, that upregulate integrins lymphocyte-function associated antigen (LFA)-1 and macrophage (Mac)-1, serving as ICAM-1 ligands. An alveolar gradient of interleukin-8 may serve as a potent chemoattractant for circulating neutrophils. Neutrophils from lung aspirates of RSV-infected infants show further signs of inflammatory and migratory activation, while soluble endothelial cell adhesion molecules (sCAMs), such as sICAM-1, have become measurable in the systemic circulation. Whether these mechanisms are solely responsible for neutrophil migration into the alveolar space remains under debate. However, data indicate that the currently postulated neutrophil influx into the lungs should rather be regarded as a neutrophil efflux from the vasculature, involving substantial neutrophil-endothelial interactions. Molecular patterns of these interactions may be clinically useful to predict outcomes of RSV LRTI and deserve further study

Viral causes of severe acute respiratory infection in hospitalized children and association with outcomes:A two-year prospective surveillance study in Suriname

BackgroundViruses are the most frequent cause of severe acute respiratory infection (SARI) in children. It is currently unknown whether presence of a virus, the number of viruses, or type of virus, are associated with clinical outcomes of pediatric SARI in developing countries.MethodsBetween 2012 and 2014 nasopharyngeal swabs and demographic and clinical variables were prospectively collected for surveillance of viral causes of SARI in Surinamese children within 48 hours after hospitalization. These swabs were tested for 18 respiratory viruses using a multiplex polymerase chain reaction (PCR) panel to identify the specific viral causes of SARI, unknown to the treating physicians. In post hoc analyses we evaluated if the PCR results, and demographic and clinical characteristics, were associated with course of disease, duration of respiratory support, and length of stay (LOS).ResultsOf a total of 316 analyzed children, 290 (92%) had one or more viruses. Rhinovirus/enterovirus (43%) and respiratory syncytial virus (34%) were most prevalent. Course of disease was mild in 234 (74%), moderate in 68 (22%), and severe in 14 (4%) children. Neither presence of a single virus, multiple viruses, or the type of virus, were different between groups. Prematurity and lower weight-for-age-z-score were independent predictors of a severe course of disease, longer duration of respiratory support, and longer LOS.ConclusionsViruses are common causes of pediatric SARI in Suriname, yet not necessarily associated with clinical outcomes. In developing countries, demographic and clinical variables can help to identify children at-risk for worse outcome, while PCR testing may be reserved to identify specific viruses, such as influenza, in specific patient groups or during outbreaks

Magnetic Characterization of Soft Magnetic Cores at Cryogenic Temperatures

It is important to investigate and understand the magnetic properties of soft magnetic materials at cryogenic temperatures for the optimal design of superconducting machines and superconducting transformers. The magnetic properties of soft magnetic materials at room temperatures have been studied extensively. However, there is almost no information available for the magnetic properties of these materials at cryogenic temperatures. This paper for the first time presents the experimental results for the magnetic characterization of four soft magnetic materials from room temperature down to 21 K. The experimental results demonstrate that the core losses at 21 K is higher than room temperature for all the materials. They also show that the permeability of all the materials reduce at 21 K compared to room temperature. The optimal temperature in terms of the best magnetic properties is identified for each material. The data presented in this paper will provide valuable guidance for practical design and optimization of superconducting machines and superconducting transformers with soft magnetic cores.</p