Repetition of estrus is the most frequent reproductive problem after breeding in dairy cattle from Rio de Janeiro, Brazil.

Reproductive efficiency is one of the key elements for any milk production system to be successful. In this regard, reproductive management must be planned properly and the identification of the main reproductive disorders that affect the herd is primordial for decisionmaking. The aim of the present study was to identify the main reproductive problems that affect dairy herds on Rio de Janeiro (RJ), Brazil. Data regarding breed, age, reproductive disorder occurrence, and breeding system were individually collected from dairy cows raised at 25 farms located at RJ. The occurrence of reproductive disorders was reported in 37% of the studied animals. Estrous repetition (76.2%) and abortion (15.6%) were the most frequent reproductive problems reported. Estrous repetition was more common in older animals (>6 years old). However, an association between abortion and age of animal was not observed, nor an association between breeding system and occurrence of abortion. The present results demonstrated that estrous repetition is the main obstacle to the reproductive efficiency in dairy herds at RJ, and that the replace of older cows by heifers is an important point within reproductive management of a dairy herd

Clustering and forecasting of dissolved oxygen concentration on a river basin

The aim of this contribution is to combine statistical methodologies to geographically classify homogeneous groups of water quality monitoring sites based on similarities in the temporal dynamics of the dissolved oxygen (DO) concentration, in order to obtain accurate forecasts of this quality variable. Our methodology intends to classify the water quality monitoring sites into spatial homogeneous groups, based on the DO concentration, which has been selected and considered relevant to characterize the water quality. We apply clustering techniques based on Kullback Information, measures that are obtained in the state space modelling process. For each homogeneous group of water quality monitoring sites we model the DO concentration using linear and state space models, which incorporate tendency and seasonality components in different ways. Both approaches are compared by the mean squared error (MSE) of forecasts

Diastolic time – frequency relation in the stress echo lab: filling timing and flow at different heart rates

A cutaneous force-frequency relation recording system based on first heart sound amplitude vibrations has been recently validated. Second heart sound can be simultaneously recorded in order to quantify both systole and diastole duration

11β-hydroxysteroid dehydrogenase type 1 has no effect on survival during experimental malaria but affects parasitemia in a parasite strain-specific manner

status: publishe

Molecular mechanics of mineralized collagen fibrils in bone

Bone is a natural composite of collagen protein and the mineral hydroxyapatite. The structure of bone is known to be important to its load-bearing characteristics, but relatively little is known about this structure or the mechanism that govern deformation at the molecular scale. Here we perform full-atomistic calculations of the three-dimensional molecular structure of a mineralized collagen protein matrix to try to better understand its mechanical characteristics under tensile loading at various mineral densities. We find that as the mineral density increases, the tensile modulus of the network increases monotonically and well beyond that of pure collagen fibrils. Our results suggest that the mineral crystals within this network bears up to four times the stress of the collagen fibrils, whereas the collagen is predominantly responsible for the material’s deformation response. These findings reveal the mechanism by which bone is able to achieve superior energy dissipation and fracture resistance characteristics beyond its individual constituents.United States. Office of Naval Research (N000141010562)United States. Army Research Office (W991NF-09-1-0541)United States. Army Research Office (W911NF-10-1-0127)National Science Foundation (U.S.) (CMMI-0642545