A review of current concepts on sex determination in animals

A journal article on the sexual determinants of farm animals.Despite being a complex development process, sex determination is important in reproduction of farm animals. Chromosome sex, which is based on the presence of sex chromosomes, is the most common to scientists. Most common to the layman, is what can be termed phenotypic sex, which is based on what can be seen in an individual. It encompasses the urogenital, external features, such as the external genitalia and secondary sex characteristics. From a molecular genetics point of view, there is also what is termed genetic sex, which is based on the presence of a sex-determining gene. In other words, an XY individual without the sex-determining gene is not a genetic male. The sex-determining gene is located on the Y-chromosome. Since 1959, when the Y-chromosome was shown to be the male-determining factor, there has been controversy as to what really determines sex in animals. However, the identification of what has been termed the sex-determining gene on the Y-chromosome (SRY) in 1990 has narrowed the controversy to the actual mechanism of sex determination. This review focuses on the genetic sex-determination mechanism by which genes determine sex, the fate of the supporting cells and evidence on issues, which are still inconclusive

The potential of single-hitched donkeys (Equus asinus) in cultivation tasks in Zimbabwe

A journal study on the use and importance of single-hitched donkeys to the draught power of Zimbabwe's rural farmers.This study was conducted at Matopos Research Station (Zimbabwe) during the 1995/96 summer cropping season to investigate the effect of soil type, animal sex and live weight of single-hitched donkeys in cultivation tasks. Twenty-four donkeys comprising males and females, equally represented in heavy (>130kg) and light (0.05) on total work done. Sex had no significant effect (P>0.05) on work output. Live weight significantly (P0.05) effect of sex and live weight on heart rate and rectal temperature changes during the post-work recovery period. Only resting time significantly (P<0.001) affected changes in the studied physiological parameters during the recovery period. The results highlighted the importance of live weight in influencing work performance draof single-hitched donkeys in cultivation tasks. Heavy donkeys of either sex are more useful than light donkeys for cultivation purposes on heavy and light soils. Live weight is more useful than other linear body measurements as a predictor of work output in cultivation tasks by single-hitched donkeys. Work-related physiological changes limit the work capacity of single working donkeys in cultivation, hence adequate rest pauses are necessar

Momentum scalar triple product as a measure of chirality in electron ionization dynamics of strongly-driven atoms

We formulate a transparent measure that quantifies chirality in single electron ionization triggered in atoms, which are achiral systems. We do so in the context of Ar driven by a new type of optical fields that consists of two non-collinear laser beams giving rise to chirality that varies in space across the focus of the beams. Our computations account for realistic experimental conditions. To define this measure of chirality, we first find the sign of the electron final momentum scalar triple product $\mathrm{{\bf{p}}_{k}\cdot ({\bf{p}}_{i}\times {\bf p}_{j})}$ and multiply it with the probability for an electron to ionize with certain values for both $\mathrm{p_{k}}$ and $\mathrm{p_{i}p_{j}}$. Then, we integrate this product over all values of $\mathrm{p_{k}}$ and $\mathrm{p_{i}p_{j}}$. We show this to be a robust measure of chirality in electron ionization triggered by globally chiral electric fields

Spatiotemporal imaging of valence electron motion

Electron motion on the (sub-)femtosecond time scale constitutes the fastest response in many natural phenomena such as light-induced phase transitions and chemical reactions. Whereas static electron densities in single molecules can be imaged in real space using scanning tunnelling and atomic force microscopy, probing real-time electron motion inside molecules requires ultrafast laser pulses. Here, we demonstrate an all-optical approach to imaging an ultrafast valence electron wave packet in real time with a time-resolution of a few femtoseconds. We employ a pump-probe-deflect scheme that allows us to prepare an ultrafast wave packet via strong-field ionization and directly image the resulting charge oscillations in the residual ion. This approach extends and overcomes limitations in laser-induced orbital imaging and may enable the real-time imaging of electron dynamics following photoionization such as charge migration and charge transfer processes

AutoSyP: A Low-Cost, Low-Power Syringe Pump for Use in Low-Resource Settings

This article describes the design and evaluation of AutoSyP, a low-cost, low-power syringe pump intended to deliver intravenous (IV) infusions in low-resource hospitals. A constant-force spring within the device provides mechanical energy to depress the syringe plunger. As a result, the device can run on rechargeable battery power for 66 hours, a critical feature for low-resource settings where the power grid may be unreliable. The device is designed to be used with 5- to 60-mL syringes and can deliver fluids at flow rates ranging from 3 to 60 mL/hour. The cost of goods to build one AutoSyP device is approximately $500. AutoSyP was tested in a laboratory setting and in a pilot clinical study. Laboratory accuracy was within 4% of the programmed flow rate. The device was used to deliver fluid to 10 healthy adult volunteers and 30 infants requiring IV fluid therapy at Queen Elizabeth Central Hospital in Blantyre, Malawi. The device delivered fluid with an average mean flow rate error of −2.3% ± 1.9% for flow rates ranging from 3 to 60 mL/hour. AutoSyP has the potential to improve the accuracy and safety of IV fluid delivery in low-resource settings

Streaking strong-field double ionization

Double ionization in intense laser fields can comprise electron correlations which manifest in the nonindependent emission of two electrons from an atom or molecule. However, experimental methods that directly access the electron emission times have been scarce. Here we explore the application of an all-optical streaking technique to strong-field double ionization, both theoretically and experimentally. We show that both sequential and nonsequential double-ionization processes lead to streaking delays that are distinct from each other and single ionization. Moreover, coincidence detection of ions and electrons provides access to the emission time difference, which is encoded in the two-electron momentum distributions. The experimental data agree very well with simulations of sequential double ionization. We further test and discuss the application of this method to nonsequential double ionization, which is strongly affected by the presence of the streaking field

Signatures of Light-Induced Potential Energy Surfaces in H2+

Using theory and Cold Target Recoil Ion Momentum Spectroscopy we find signatures of light-induced molecular potential energy surfaces in the 3-dimensional proton momentum distributions of dissociating H+2. © 2020 Journal of Physics: Conference Series. All rights reserved