Out-of-sample comparison of copula specifications in multivariate density forecasts

We introduce a statistical test for comparing the predictive accuracy of competing copula specifications in multivariate density forecasts, based on the Kullback-Leibler Information Criterion (KLIC). The test is valid under general conditions: in particular it allows for parameter estimation uncertainty and for the copulas to be nested or non-nested. Monte Carlo simulations demonstrate that the proposed test has satisfactory size and power properties in finite samples. Applying the test to daily exchange rate returns of several major currencies against the US dollar we find that the Student's t copula is favored over Gaussian, Gumbel and Clayton copulas. This suggests that these exchange rate returns are characterized by symmetric tail dependence.

Partial Likelihood-Based Scoring Rules for Evaluating Density Forecasts in Tails

We propose new scoring rules based on partial likelihood for assessing the relative out-of-sample predictive accuracy of competing density forecasts over a specific region of interest, such as the left tail in financial risk management. By construction, existing scoring rules based on weighted likelihood or censored normal likelihood favor density forecasts with more probability mass in the given region, rendering predictive accuracy tests biased towards such densities. Our novel partial likelihood-based scoring rules do not suffer from this problem, as illustrated by means of Monte Carlo simulations and an empirical application to daily S\&P 500 index returns.

Low-carbohydrate diets affect energy balance and fuel homeostasis differentially in lean and obese rats

In parallel with increased prevalence of overweight people in affluent societies are individuals trying to lose weight, often using low-carbohydrate diets. Nevertheless, long-term metabolic consequences of those diets, usually high in (saturated) fat, remain unclear. Therefore, we investigated long-term effects of high-fat diets with different carbohydrate/protein ratios on energy balance and fuel homeostasis in obese (fa/fa) Zucker and lean Wistar rats. Animals were fed high-carbohydrate (HC), high-fat (HsF), or low-carbohydrate, high-fat, high-protein (LC-HsF-HP) diets for 60 days. Both lines fed the LC-HsF-HP diet displayed reduced energy intake compared with those fed the HsF diet (Zucker, -3.7%) or the HC diet (Wistar rats, -12.4%). This was not associated with lower weight gain relative to HC fed rats, because of increased food efficiencies in each line fed HsF and particularly LC-HsF-HP food. Zucker rats were less glucose tolerant than Wistar rats. Lowest glucose tolerances were found in HsF and particularly in LC-HsF-HP-fed animals irrespective of line, but this paralleled reduced plasma adiponectin levels, elevated plasma resistin levels, higher retroperitoneal fat masses, and reduced insulin sensitivity (indexed by insulin-induced hypoglycemia) only in Wistar rats. In Zucker rats, however, improved insulin responses during glucose tolerance testing and tendency toward increased insulin sensitivities were observed with HsF or LC-HsF-HP feeding relative to HC feeding. Thus, despite adverse consequences of LC-HsF diets on blood glucose homeostasis, principal differences exist in the underlying hormonal regulatory mechanisms, which could have benefits for B-cell functioning and insulin action in the obese state but not in the lean state.

Where to go in the near future: diverging perspectives on online public service delivery

Although the electronic government is under heavy development, a clear vision doesn’t seem to exist. In this study 20 interviews among leaders in the field of e-government in the Netherlands resulted in different perspectives on the future of electronic public service delivery. The interviews revealed different objectives and interpretations of the presuppositions regarding citizens’ desires. Opinions about channel approaches and ‘trigger services’ appeared to vary. Furthermore, the respondents didn’t agree on the number of contact moments between citizen and government, had different opinions about digital skills, pled for various designs of the electronic government and placed the responsibility for electronic service delivery in different hands. Conclusion is that there is a lack of concepts on how to do things. Everybody talks about eGovernment, but all have different interpretations. \u

Consistent treatment of hydrophobicity in protein lattice models accounts for cold denaturation

The hydrophobic effect stabilizes the native structure of proteins by minimizing the unfavourable interactions between hydrophobic residues and water through the formation of a hydrophobic core. Here we include the entropic and enthalpic contributions of the hydrophobic effect explicitly in an implicit solvent model. This allows us to capture two important effects: a length-scale dependence and a temperature dependence for the solvation of a hydrophobic particle. This consistent treatment of the hydrophobic effect explains cold denaturation and heat capacity measurements of solvated proteins.Comment: Added and corrected references for design procedure in main text (p. 2) and in Supplemental Information (p. 8

Model file name: DNA-short-helix.x3d

Model file name: DNA-short-helix.x3d Authors: Michelle E Howell, Karin van Dijk, Rebecca L Roston This is a teaching model of a DNA helix in which the atoms are colored by heteroatom (PDB: 1lmb). This model is designed to go with a teaching module comparing DNA and RNA basic structures and functions, and with one that studies transcription factor-DNA binding. The printable model is already uploaded to Shapeways.com in the MacroMolecules shop under the name “DNA helix - polynucleotide molecule”. This model has been printed successfully using these parameters on Shapeways’ binder jetting printer in the Coated Full Color Sandstone material

Model file name: RNA-short-helix.x3d

Model file name: RNA-short-helix.x3d Authors: Michelle E Howell, Karin van Dijk, Rebecca L Roston This is a teaching model of a DNA helix in which the atoms are colored by heteroatom (PDB: 1lmb). This model is designed to go with a teaching module comparing DNA and RNA basic structures and functions. The printable model is already uploaded to Shapeways.com in the MacroMolecules shop under the name “RNA helix - polynucleotide molecule”. This model has been printed successfully using these parameters on Shapeways’ binder jetting printer in the Coated Full Color Sandstone material

Model file name: H1-protein.stl

Model file name: H1-protein.stl Authors: Michelle E Howell, Karin van Dijk, Rebecca L Roston This is a teaching model of a crude representation of an H1-protein intended to accompany the nucleosome and a long, thin double stranded DNA helix model in order to illustrate DNA packaging and supercoiling. This model is designed to go with a teaching module on DNA supercoiling. The printable model is already uploaded to Shapeways.com in the MacroMolecules shop under the name “Histone H1 protein”. This model has been printed successfully using these parameters on Shapeways’ laser sintering printer in the following materials: Strong & Flexible Plastic, and Stainless Steel

Model file name: Nucleosome.stl

Model file name: Nucleosome.stl Authors: Michelle E Howell, Karin van Dijk, Rebecca L Roston This is a teaching model of a crude representation of a nucleosome intended to accompany the H1 histone protein and a long, thin double stranded DNA helix model in order to illustrate DNA packaging and supercoiling. This model is designed to go with a teaching module on DNA supercoiling. The printable model is already uploaded to Shapeways.com in the MacroMolecules shop under the name “Nucleosome”. This model has been printed successfully using these parameters on Shapeways’ laser sintering printer in the Strong & Flexible Plastic material

Model file name: ssDNA.stl

Model file name: ssDNA.stl Authors: Michelle E Howell, Karin van Dijk, Rebecca L Roston This is a teaching model of a single stranded piece of DNA in stick representation (PDB: 1ehz). This model is designed to go with a teaching module comparing DNA and RNA basic structures and functions. The printable model is already uploaded to Shapeways.com in the MacroMolecules shop under the name “ssDNA”. This model has been printed successfully using these parameters on Shapeways’ laser sintering printer in the Elasto Plastic material