On the minimization of the prime power consumption of a coupling-modulated gas laser transmitter

The prime power requirements of a coupling-modulated gas laser transmitter are presented. The latter consists of a gas discharge tube and electro-optic modulator inside a laser resonator. In performing the calculations, the laser discharge length and the modulator voltage are simultaneously varied so that the transmitted power remains constant. In this way, tradeoffs can be made between the prime power supplied individually to the discharge tube and to the modulator driver to obtain a transmitter configuration which minimizes the total prime power consumption. An analytical expression is derived which describes the effects of information bandwidth and transmitter output power on the prime power requirements. Specific numerical results are obtained for a CO2 laser transmitter based on presently available experimental data

A polynomial time algorithm for calculating the probability of a ranked gene tree given a species tree

In this paper, we provide a polynomial time algorithm to calculate the probability of a {\it ranked} gene tree topology for a given species tree, where a ranked tree topology is a tree topology with the internal vertices being ordered. The probability of a gene tree topology can thus be calculated in polynomial time if the number of orderings of the internal vertices is a polynomial number. However, the complexity of calculating the probability of a gene tree topology with an exponential number of rankings for a given species tree remains unknown

Squamscott Project Newfields Open Space Committee

Through the Newfields Open Space Committee (NOSC) the objectives under the Squamscott Project were to educate the citizens of Newfields on conservation options and estate planning, the goals and objectives of the NOSC, and to finalize a natural resource prioritization for critical areas in town in need of protection efforts. The NOSC contracted with the Rockingha m County Conservation District to assist with these efforts, and to provide assistance with the coordination of conservation projects and the preparation of funding applications to leverage the existing open space bond fund

Thiamine Acquisition Strategies Impact Metabolism and Competition in the Gut Microbe Bacteroides thetaiotaomicron.

Thiamine (vitamin B1) is an essential cofactor for all organisms. Humans primarily acquire thiamine through their diet, and thiamine deficiencies have adverse neurological effects. However, the role gut microbes play in modulating thiamine availability is poorly understood, and little is known about how thiamine impacts the stability of microbial gut communities. To investigate thiamine's role in the gut, we utilized the model gut microbe Bacteroides thetaiotaomicron. Transcriptome sequencing (RNA-seq) revealed a global downregulation of thiamine and amino acid biosynthesis, glycolysis, and purine metabolism when thiamine was present. Using genetic mutants with thiamine biosynthesis and transport locus mutations, we determined both systems were critical for growth in thiamine-deficient medium. The defect in the double transport mutant suggests an uncharacterized feedback mechanism between thiamine transport and biosynthesis in B. thetaiotaomicron. Mutant phenotypes were recapitulated during pairwise competitions, reinforcing the importance of encoding versatile thiamine acquisition mechanisms when thiamine concentrations are variable. In addition, liquid chromatography-mass spectrometry (LC-MS) analyses corroborate that exogenous thiamine levels affect the internal thiamine pool of B. thetaiotaomicron. Furthermore, we computationally examined the ability of other gut microbes to acquire thiamine and identified lineage-specific differences in thiamine acquisition strategies. Among the Bacteroidetes, the capacities for both thiamine transport and biosynthesis are common. Together, these data show that thiamine acquisition mechanisms used by B. thetaiotaomicron not only are critical for its physiology and fitness but also provide the opportunity to model how other gut microbes may respond to the shifting availability of thiamine in the gut. IMPORTANCE Variation in the ability of gut microbes to transport, synthesize, and compete for vitamin B1 (thiamine) is expected to impact the structure and stability of the microbiota, and ultimately this variation may have both direct and indirect effects on human health. Our study identifies the diverse strategies employed by gut Bacteroidetes to acquire thiamine. We demonstrate how the presence or absence of thiamine biosynthesis or transport dramatically affects the abundance of B. thetaiotaomicron in a competitive environment. This study adds further evidence that altering the presence or concentrations of water-soluble vitamins such as thiamine may be an effective method for manipulating gut community composition. In turn, targeted thiamine delivery could be used therapeutically to alter dysbiotic communities linked to disease. Author Video: An author video summary of this article is available

Micro-feedback skills workshop impacts perceptions and practices of doctoral faculty

Background: Doctoral supervision is a distinct form of supervision with clearly defined responsibilities. One of these is the delivery of effective face-to-face feedback to allow supervisees to improve upon their performances. Unfortunately, doctoral supervisors, especially of health sciences, are often not trained in supervisory skills and therefore practice mostly on a trial and error basis. Lack of understanding of the feedback process leads to incongruence in how supervisors and supervisees perceive feedback. However, standardized training practices like microteaching can allow supervisors to acquire effective feedback practices. In this study we employed a schematic approach of microteaching, that is micro-feedback, in a workshop to develop feedback skills of doctoral supervisors, and assessed the overall effectiveness of this training using the Kirkpatrick evaluation framework.Methodology: This was a Quasi-experimental study with a repeated measures and a two-group separate sample pre-post test design. A micro-feedback skills workshop was organized to enhance feedback skills of doctoral supervisors using microteaching technique. The first two levels of the Kirkpatrick evaluation model were used to determine the workshop's effectiveness. An informal Objective Structured Teaching Exercise (OSTE) was used to assess feedback skills of the supervisors, both before and after the workshop. A questionnaire was developed to compare pre-and post-workshop perceptions of the supervisors (n = 17) and their corresponding supervisees (n = 34) regarding the ongoing feedback practice.Results: Despite the hectic schedule, most doctoral supervisors (17 of 24, 71%) were willing to undertake faculty development training. Participants indicated a high level of satisfaction with the workshop. A learning gain of 56% was observed on pre-post OSTE scores. Prior to the workshop, perceptions of how supervisees should be given the feedback differed significantly between supervisors and supervisees with an effect size difference of r = 0.30. After the workshop there was a negligible difference in perceptions between supervisors and supervisees (r = .001). Interestingly, supervisors shifted their perceptions more toward those that were originally held by the supervisees.Conclusions: These findings suggest that well-designed and properly assessed structured programs such as micro-feedback workshops can improve how doctoral supervisors provide feedback to their supervisees and align supervisors' perceptions of that feedback with those of their supervisees.</p

Characterization of the Q-switched MOBLAS Laser Transmitter and Its Ranging Performance Relative to a PTM Q-switched System

A prototype Q-switched Nd:YAG laser transmitter intended for use in the NASA mobile laser ranging system was subjected to various tests of temporal pulse shape and stability, output energy and stability, beam divergence, and range bias errors. Peak to peak variations in the mean range were as large as 30 cm and drift rates of system bias with time as large as 6 mm per minute of operation were observed. The incorporation of a fast electro-optic cavity dump into the oscillator gave significantly improved results. Reevaluation of the ranging performance after modification showed a reduction in the peak to peak variation in the mean range to the 2 or 3 cm level and a drift rate of system time biases of less than 1 mm per minute of operation. A qualitative physical explanation for the superior performance of cavity dumped lasers is given

Isolation of microsatellite loci in the Capricorn silvereye, Zosterops lateralis chlorocephalus (Aves : Zosteropidae)

The Capricorn silvereye (Zosterops lateralis chlorocephalus ) is ideally suited to investigating the genetic basis of body size evolution. We have isolated and characterized a set of microsatellite markers for this species. Seven out of 11 loci were polymorphic. The number of alleles detected ranged from two to five and observed heterozygosities between 0.12 and 0.67. One locus, ZL49, was found to be sex-linked. This moderate level of diversity is consistent with that expected in an isolated, island population