Evaluation of the Karras Spermdensimeter in Relation to the Neubauer Counting Chamber for Sperm Concentration Measurement in Boar Semen

The correct measurement of spermatic concentration in boar semen is one of the basic tasks routinely performed at the Swine Artificial Insemination Center (CIAS). This article explains two experiments whose objectives were: Experiment 1: This trial had two objectives: (1) to evaluate the precision of the spermdensimeter (SPM) with relation to the Neubauer count chamber (CN) which is considered the standard technique in the field and (2) to correct the scale on the SPM table. Experiment 2: This trial also had two objectives: (1) to evaluate the time and repetitions required in the SPM and (2) to compare the SPM adjusted table produced in Expt 1 with the SPM standard table. The methods in Expt 1 were used to measure total spermatic concentration in 141 boar ejaculates. The average spermatic concentrations (10(6) spermatozoids/ml) and average dose number were 229.1 and 22.6 for CN, and 283.6 and 28.0 for SPM. These results indicate that the SPM has a tendency to overestimate spermatic concentration with relation to the CN. The SPM produced a smaller coefficient of variation and needed lesser examination time than the CN (p < 0.05). The SPM adjusted table created in Expt 1 produced similar results as the SPM and CN standard tables (2.96 billion live spermatozoids/dose vs 2.36 billion live spermatozoids/dose). Incorporation and evaluation of supplemental data from other CIAS regarding the use of the SPM adjusted table in the field entitled 'Adjusted Table for Karras Spermdensimeter LPS-FMVZ-USP' would be valuable to prove its efficiency.     

Excitation spectra of circular, few-electron quantum dots

Studies of the ground and excited states in semiconductor quantum dots containing 1 to 12 electrons showed that the quantum numbers of the states in the excitation spectra can be identified and compared with exact calculations. A magnetic field induces transitions between the ground and excited states. These transitions were analyzed in terms of crossings between single-particle states, singlet-triplet transitions, spin polarization, and Hund's rule. These impurity-free quantum dots allow "atomic physics" experiments to be performed in magnetic field regimes not accessible for atoms.     

Effects of hyperinsulinaemia under euglycaemic condition on liver fat metabolism in dairy cows in early and mid-lactation

The objective was to examine the effects of insulin under euglycaemic conditions on liver long chain fatty acids (LCFA) metabolism with special focus on the aetiology of hepatic lipidosis in early lactation. A 4-day hyperinsulinaemic-euglycaemic clamp (clamp) was conducted on four dairy cows starting in weeks 4 and 17 postpartum. Insulin was infused continuously (1 microg/kg BW per h) and a 50% glucose solution was infused to maintain euglycaemia. Liver biopsies were taken 6 days before, the last day of, and 5 days after the clamp, and blood samples were taken in the same period. In the liver tissue, the relative triglyceride content decreased (P < 0.01) and the glycogen content increased (P < 0.0001) in response to the clamp. Hepatic in vitro palmitate oxidation capacity was lowest during the clamp period and could be explained by a significant decrease in incomplete oxidation (ketogenesis) (P < 0.04) and a tendency to a decreased complete oxidation of palmitate (P < 0.10). Plasma non-esterified fatty acids concentration was decreased during the clamp in early lactation (P < 0.05) but there was no effect on the mid-lactation clamp. The present study shows that increased insulin under euglycaemic conditions seems to depress hepatic LCFA oxidation capacity. However, in terms of preventing hepatic lipidosis, the anti-lipolytic effect of insulin on adipose tissue, which results in decreased mobilization of and hence hepatic load with LCFA, appears more important.     

Magnetic Collapse in Transition Metal Oxides at High Pressure: Implications for the Earth

Magnetic collapse in transition metal ions is predicted from first-principles computations at pressures reached in the Earth's lower mantle and core. Magnetic collapse would lead to marked changes in geophysically important properties, such as elasticity and conductivity, and also to different geochemical behavior, such as element partitioning, than estimated by extrapolating low-pressure data, and thus change the understanding of Earth's structure and evolution. Magnetic collapse results from band widening rather than from changes in crystal field splitting under pressure. Seismic anomalies in the outer core and the lowermost mantle may be due to magnetic collapse of ferrous iron, dissolved in iron liquid in the outer core, and in solution in magnesiowustite in the lowermost mantle.     

Integration Between Different Hypothalamic Nuclei Involved in Stress and GnRH Secretion in the Ewe

This study investigated possible integrated links in the neuroanatomical pathways through which the activity of neurones in the paraventricular nucleus and arcuate nucleus may modulate suppression of gonadotrophin‐releasing hormone (GnRH) secretion during stressful situations. Double‐label immunofluorescence and laser scanning confocal microscopy were used to examine the hypothalamic sections from the follicular phase ewes. Noradrenergic terminals were in close contact with 65.7 ± 6.1% corticotrophin‐releasing hormone (CRH) and 84.6 ± 3.2% arginine vasopressin (AVP) cell bodies in the paraventricular nucleus but not with β‐endorphin cell bodies in the arcuate nucleus. Furthermore, γ‐amino butyric acid (GABA) terminals were close to 80.9 ± 3.5% CRH but no AVP cell bodies in the paraventricular nucleus, as well as 60.8 ± 4.1%β‐endorphin cell bodies in the arcuate nucleus. Although CRH, AVP and β‐endorphin cell terminals were identified in the medial pre‐optic area, no direct contacts with GnRH cell bodies were observed. Within the median eminence, abundant CRH but not AVP terminals were close to GnRH cell terminals in the external zone; whereas, β‐endorphin cells and terminals were in the internal zone. In conclusion, neuroanatomical evidence is provided for the ewe supporting the hypothesis that brainstem noradrenergic and hypothalamic GABA neurones are important in modulating the activity of CRH and AVP neurones in the paraventricular nucleus, as well as β‐endorphin neurones in the arcuate nucleus. These paraventricular and arcuate neurones may also involve interneurones to influence GnRH cell bodies in medial pre‐optic area, whereas the median eminence may provide a major site for direct modulation of GnRH release by CRH terminals.