Livestock and Small Farmer Labor Supply

Egypt's rural population contains a high proportion of farmers with very small farms. Average farm size, now thought to be less than 2.5 feddan, continues to decline under the pressure of the growing rural population. More than two thirds of the farming units are less than three feddan in size. Often it is asserted that a two to three feddan farm is necessary for "subsistence" or to avoid the need to work for others. Surprisingly, however, this study indicates that smaller farmers are not very active participants in hired farm labor markets. How, then, can such farmers survive? We contend that livestock production provides a vital alternative source of employment, food, and income to the small farmer. Livestock production may represent an important survival strategy for Egypt's small farmers. The authors discussed the problems in drawing upon national statistics as a source of information about livestock. Survey data found that livestock production generates a higher proportion of income on small farms than on large farms, and showed that small farmers devote more labor to livestock than to crops. Livestock production provides attractive opportunities for Egypt's farmers, particularly small farmers, to augment farm incomes as well as to obtain vital human food nutrients. An estimated sixty-five percent of all equivalent animal units were found to be on farms with three feddan and less. More than three quarters of the edible milk and dairy products are home consumed on farms on this size. Given the fact that livestock production is so heavily concentrated on these small farms and that they consume such a high proportion of what they produce, it follows that these farms cannot be counted upon to supply a very significant amount of dairy and other livestock products to Egypt's growing off-farm population. But data presented here indicates the opposite. Because they are so much more productive than larger farms, the amount of livestock products w hich is marketed by small farms exceeds that marketed by larger farms, when measured on either a per feddan or per animal unit basis. Is the intensification in livestock production which Egypt has experienced during the past two decades a temporary or a long term phenomenon? Apparently, it seems that livestock intensification cannot normally succeed in developing countries, in the face of high human population densities and the resultant competition for crop land. Data presented in this study seems to indicate that just the opposite may be true in Egypt during the current epoch. Why? Will the current situation last? Egypt's farm population has continued to grow on a fixed base of land. The average farm size has become smaller it is currently estimated to be about 2.4 feddan and the farm family labor available per farm and per unit area of land has increased. Evidence presented here indicates that livestock production has a much greater capacity than crop production for utilizing additional family labor. This factor favors livestock production, aside from the favorable relative price situation which exists. Livestock production has normally been intensified when declines in grain price have been the stimulus for a shift from arable to relatively more !intensive livestock farming."[14] Clearly, government policies have held grain and other crop prices relative to livestock prices. Without doubt this has contributed to livestock intensification. Should the Egyptian government decide to permit crop prices to rise towards their international trading equivalent, then the current incentives to produce livestock would be greatly reduce

Photon number resolving detection using time-multiplexing

Detectors that can resolve photon number are needed in many quantum information technologies. In order to be useful in quantum information processing, such detectors should be simple, easy to use, and be scalable to resolve any number of photons, as the application may require great portability such as in quantum cryptography. Here we describe the construction of a time-multiplexed detector, which uses a pair of standard avalanche photodiodes operated in Geiger mode. The detection technique is analysed theoretically and tested experimentally using a pulsed source of weak coherent light.Comment: 20 pages, 14 figures, accepted to Journal of Modern Optic

Capacities of silos and weights of silage

Cover title.Includes bibliographical references

Photon number resolution using a time-multiplexed single-photon detector

Photon number resolving detectors are needed for a variety of applications including linear-optics quantum computing. Here we describe the use of time-multiplexing techniques that allows ordinary single photon detectors, such as silicon avalanche photodiodes, to be used as photon number-resolving detectors. The ability of such a detector to correctly measure the number of photons for an incident number state is analyzed. The predicted results for an incident coherent state are found to be in good agreement with the results of a proof-of-principle experimental demonstration.Comment: REVTeX4, 6 pages, 8 eps figures, v2: minor changes, v3: changes in response to referee report, appendix added, 1 reference adde

Electrostatic potential and valence modulation in La0.7Sr0.3MnO3 thin films

The Mn valence in thin film La0.7Sr0.3MnO3 was studied as a function of film thickness in the range of 1–16 unit cells with a combination of non-destructive bulk and surface sensitive X-ray absorption spectroscopy techniques. Using a layer-by-layer valence model, it was found that while the bulk averaged valence hovers around its expected value of 3.3, a significant deviation occurs within several unit cells of the surface and interface. These results were supported by first principles calculations. The surface valence increases to up to Mn3.7+, whereas the interface valence reduces down to Mn2.5+. The change in valence from the expected bulk value is consistent with charge redistribution due to the polar discontinuity at the film-substrate interface. The comparison with theory employed here illustrates how this layer-by-layer valence evolves with film thickness and allows for a deeper understanding of the microscopic mechanisms at play in this effect. These results offer insight on how the two-dimensional electron gas is created in thin film oxide alloys and how the magnetic ordering is reduced with dimensionality

Genome-wide signatures of convergent evolution in echolocating mammals

Evolution is typically thought to proceed through divergence of genes, proteins, and ultimately phenotypes(1-3). However, similar traits might also evolve convergently in unrelated taxa due to similar selection pressures(4,5). Adaptive phenotypic convergence is widespread in nature, and recent results from a handful of genes have suggested that this phenomenon is powerful enough to also drive recurrent evolution at the sequence level(6-9). Where homoplasious substitutions do occur these have long been considered the result of neutral processes. However, recent studies have demonstrated that adaptive convergent sequence evolution can be detected in vertebrates using statistical methods that model parallel evolution(9,10) although the extent to which sequence convergence between genera occurs across genomes is unknown. Here we analyse genomic sequence data in mammals that have independently evolved echolocation and show for the first time that convergence is not a rare process restricted to a handful of loci but is instead widespread, continuously distributed and commonly driven by natural selection acting on a small number of sites per locus. Systematic analyses of convergent sequence evolution in 805,053 amino acids within 2,326 orthologous coding gene sequences compared across 22 mammals (including four new bat genomes) revealed signatures consistent with convergence in nearly 200 loci. Strong and significant support for convergence among bats and the dolphin was seen in numerous genes linked to hearing or deafness, consistent with an involvement in echolocation. Surprisingly we also found convergence in many genes linked to vision: the convergent signal of many sensory genes was robustly correlated with the strength of natural selection. This first attempt to detect genome-wide convergent sequence evolution across divergent taxa reveals the phenomenon to be much more pervasive than previously recognised

Ultrafast Laser-Based Spectroscopy and Sensing: Applications in LIBS, CARS, and THz Spectroscopy

Ultrafast pulsed lasers find application in a range of spectroscopy and sensing techniques including laser induced breakdown spectroscopy (LIBS), coherent Raman spectroscopy, and terahertz (THz) spectroscopy. Whether based on absorption or emission processes, the characteristics of these techniques are heavily influenced by the use of ultrafast pulses in the signal generation process. Depending on the energy of the pulses used, the essential laser interaction process can primarily involve lattice vibrations, molecular rotations, or a combination of excited states produced by laser heating. While some of these techniques are currently confined to sensing at close ranges, others can be implemented for remote spectroscopic sensing owing principally to the laser pulse duration. We present a review of ultrafast laser-based spectroscopy techniques and discuss the use of these techniques to current and potential chemical and environmental sensing applications

Adaptations of Avian Flu Virus Are a Cause for Concern

We are in the midst of a revolutionary period in the life sciences. Technological capabilities have dramatically expanded, we have a much improved understanding of the complex biology of selected microorganisms, and we have a much improved ability to manipulate microbial genomes. With this has come unprecedented potential for better control of infectious diseases and significant societal benefit. However, there is also a growing risk that the same science will be deliberately misused and that the consequences could be catastrophic. Efforts to describe or define life-sciences research of particular concern have focused on the possibility that knowledge or products derived from such research, or new technologies, could be directly misapplied with a sufficiently broad scope to affect national or global security. Research that might greatly enhance the harm caused by microbial pathogens has been of special concern (1–3). Until now, these efforts have suffered from a lack of specificity and a paucity of concrete examples of “dual use research of concern” (3). Dual use is defined as research that could be used for good or bad purposes. We are now confronted by a potent, real-world example