Productivity of Florida Springs: first semi-annual report to Biology Division, Office of Naval Research, progress from June 1, 1952 to January 31, 1953

Work has begun on studying the factors responsible for productivity in the Florida springs, which are nearly constant temperature, constant chemical, steady state giant laboratories. Progress has been made on five aspects: qualitative description, quantitative description, completion of knowledge of chemical factors, measurement of productivity , development of productivity theory. Measurement of the primary productivity in Silver Springs and Green Cove Springs by two new methods: the raising of organisms in cages, and the measurement of night & day differences in oxygen downstream agree roughly. Production in these springs is greater than previous production figures reported for marine, fresh water, and land areas. Instantaneous measures of production show large variations with season, time of day, cloud cover. Production estimates range from 11,000 lbs per acre per year to 70,000 lbs. glucose per acre per year during daylight hours. Essential stability of the springs environment has been shown with respect to temperature, phosphorus, and plant cover. A correlation of species number with lack of stability has been shown with insects. Quantitative studies have shown very large plant base to pyramids of mass. Correlation of marine invasion with chlorinity has been shown. The essential aspects of pH regulated phosphorus geochemistry in Florida have been outlined. Some theoretical ideas on productivity have been evolved. Mapping of sessile organisms in springs and taxonomic identification of dominants are half completed. Plans for second six months include measurement of herbivore and carnivore production rates and completion of food chain efficiency determinations in Silver Springs as a preparation for subsequent comparisons between springs. (34pp.

The Nystrom plus Correction Method for Solving Bound State Equations in Momentum Space

A new method is presented for solving the momentum-space Schrodinger equation with a linear potential. The Lande-subtracted momentum space integral equation can be transformed into a matrix equation by the Nystrom method. The method produces only approximate eigenvalues in the cases of singular potentials such as the linear potential. The eigenvalues generated by the Nystrom method can be improved by calculating the numerical errors and adding the appropriate corrections. The end results are more accurate eigenvalues than those generated by the basis function method. The method is also shown to work for a relativistic equation such as the Thompson equation.Comment: Revtex, 21 pages, 4 tables, to be published in Physical Review

Ready for Fall? Near-Term Effects of Voluntary Summer Learning Programs on Low-Income Students' Learning Opportunities and Outcomes

This report is the second of five volumes from a five-year study, funded by The Wallace Foundation and conducted by the RAND Corporation, designed as a randomized controlled trial that assesses student outcomes in three waves: in the fall after the 2013 summer program (reported here), at the end of the school year following the program, and after a second summer program in 2014 (to show the cumulative effects of two summer programs). The goal of the study is to answer one key question: Do voluntary, district-run summer programs that include academics and enrichment activities improve student academic achievement and other outcomes, such as social and emotional competence

Latest Results from Heavy Quark Simulations

The status of b-bbar and c-cbar calculations, numerical and analytic, are reviewed. The extraction of alpha_s and quark masses from spectrum calculations is discussed. The NRQCD and Improved Heavy Wilson formulations of heavy quarks are compared, and recent calculations using a Heavy Staggered formulation are discussed.Comment: 15 pages, latex, 9 postscript figures, self-unpacking uuencoded compressed file, requires espcrc2.sty (included) and epsf.sty. Contribution to Lattice '9

Learning From Summer: Effects of Voluntary Summer Learning Programs on Low-Income Urban Youth

The largest-ever study of summer learning finds that students with high attendance in free, five to six-week, voluntary summer learning programs experienced educationally meaningful benefits in math and reading.The findings are important because children from low-income families lose ground in learning over the summer compared to their more affluent peers. Voluntary, district-run summer programs could help shrink this gap and have the potential to reach more students than traditional summer school or smaller-scale programs run by outside organizations. Yet until now little has been known about the impact of these programs and how they can succeed. Wallace's $50 million National Summer Learning Project seeks to help provide answers.Since 2011, five urban school districts and their partners, the RAND Corporation and Wallace have been working together to find out whether and how voluntary-attendance summer learning programs combining academics and enrichment can help students succeed in school.Starting in 2013, RAND conducted a randomized controlled trial (RCT) in five districts—Boston; Dallas; Duval County, Florida; Pittsburgh; and Rochester—to evaluate educational outcomes, focusing on children who were in 3rd grade in spring of that year. The 5,600 students who applied to summer programs were randomly assigned to one of two groups—those selected to take part in the programs for two summers (the treatment group) and those not selected (the control group). The study analyzed outcomes for 3,192 students offered access to the programs.Researchers found that those who attended a five-to-six-week summer program for 20 or more days in 2013 did better on state math tests than similar students in the control group. This advantage was statistically significant and lasted through the following school year. The results are even more striking for high attenders in 2014: They outperformed control group students in both math and English Language Arts (ELA), on fall tests and later, in the spring. The advantage after the second summer was equivalent to 20-25 percent of a year's learning in math and ELA.These findings are correlational but controlled for prior achievement and demographics, giving researchers confidence that the benefits are likely due to the programs and meeting the requirements for promising evidence under the Every Student Succeeds Act.High-attending students were also rated by teachers as having stronger social and emotional competencies than the control group students; however, researchers have less confidence that this was due to the programs, given the lack of prior data on these competencies.About 60 percent of students attending at least one day met the 20-day threshold that was defined as high attendance.Separately, the study also examined the impact of the programs on all students who were offered access, whether or not they actually attended. Because many students did not attend at a high level, and some didn't attend at all, the average benefits for all of these students were smaller and not statistically significant, with the exception of a modest but educationally meaningful boost in math scores in the fall after the first summer equivalent to 15 percent of a year's learning. These findings are causal, meaning that researchers are confident that they were due to the programs, and meet the standard of strong evidence under the Every Student Succeeds Act.For students to experience lasting benefits from attending summer programs, the report recommends that districts: run programs for at least five weeks; promote high attendance; include sufficient instructional time and protect it; invest in instructional quality; and factor in attendance and likely no-show rates when staffing the programs in order to lower per-student costs

Centrifugation and decontamination procedures selectively impair recovery of important populations in Mycobacterium smegmatis

This work was supported by PreDiCT-TB (SMDO XEU-07).Diagnosis and treatment monitoring of patients with tuberculosis (TB) requires detection of all viable mycobacteria in clinical samples. Quantitation of Mycobacterium tuberculosis (Mtb) in sputum is commonly performed by culture after sample decontamination to prevent overgrowth by contaminant organisms. Exponentially growing cultures have cells that predominately lack non-polar lipid bodies whereas stationary cultures have a predominance of cells with non-polar lipid bodies. This may reflect rapidly growing ‘active’ and non-replicating ‘persister’ sub-populations respectively in sputum from TB patients. We investigated the effect of decontamination on culture-based quantitation of exponential and stationary phase cultures of Mycobacterium smegmatis in an artificial sputum model. Exponentially growing populations were between 89 and 50 times more susceptible to decontamination than stationary phase cultures when quantified by most probable number and colony forming units. These findings suggest that decontamination selectively eliminates the ‘active’ population. This may impair diagnostic sensitivity, treatment monitoring, and compromise clinical trials designed to identify new antibiotic combinations with activity against all mycobacterial cell states.PostprintPeer reviewe

Association of Hepcidin-25 with survival after kidney transplantation

Background Hepcidin is considered the master regulator of iron homoeostasis. Novel hepcidin antagonists have recently been introduced as potential treatment for iron-restricted anaemia. Meanwhile, serum hepcidin has been shown to be positively associated with cardiovascular disease and inversely with acute kidney injury. These properties may lead to contrasting effects, especially in renal transplant recipients (RTR), which are prone to cardiovascular diseases and graft failure. To date, the role of serum hepcidin in RTR is unknown. We, therefore, prospectively determined the association of serum hepcidin with risk of graft failure, cardiovascular mortality and all-cause mortality in RTR. Materials and methods Serum hepcidin was assessed in an extensively phenotyped RTR cohort by dual-monoclonal sandwich ELISA specific immunoassay. Statistical analyses were performed using univariate linear regression followed by stepwise backward linear regression. Cox proportional hazard regression models were performed to determine prospective associations. Results We included 561 RTR (age 51 +/- 12 years). Mean haemoglobin (Hb) was 8.6 +/- 1.0 mM. Median [IQR] serum hepcidin was 7.2 [3.2-13.4] ng/mL. Mean estimated glomerular filtration rate was 47 +/- 16 mL/min/ 1.73 m(2). In univariate Cox regression analyses, serum hepcidin was not associated with risk of graft failure, cardiovascular mortality or all-cause mortality. Notably, after adjustment for high sensitivity C-reactive protein and ferritin, serum hepcidin became negatively associated with all-cause mortality (hazard ratio 0.89; 95% confidence interval 0.80-0.99, P = 0.3). Conclusions In this study, we did not find an association between serum hepcidin and outcomes, that is graft failure, cardiovascular mortality or all-cause mortality. Based on our results, it is questionable whether serum hepcidin may be used to predict a beneficial effect of hepcidin antagonists

Structural and functional analysis of APOA5 mutations identified in patients with severe hypertriglyceridemia

During the diagnosis of three unrelated patients with severe hypertriglyceridemia, three APOA5 mutations [p.(Ser232_Leu235)del, p.Leu253Pro, and p.Asp332ValfsX4] were found without evidence of concomitant LPL, APOC2, or GPIHBP1 mutations. The molecular mechanisms by which APOA5 mutations result in severe hypertriglyceridemia remain poorly understood, and the functional impairment/s induced by these specific mutations was not obvious. Therefore, we performed a thorough structural and functional analysis that included follow-up of patients and their closest relatives, measurement of apoA-V serum concentrations, and sequencing of the APOA5 gene in 200 nonhyperlipidemic controls. Further, we cloned, overexpressed, and purified both wild-type and mutant apoA-V variants and characterized their capacity to activate LPL. The interactions of recombinant wild-type and mutated apoA-V variants with liposomes of different composition, heparin, LRP1, sortilin, and SorLA/LR11 were also analyzed. Finally, to explore the possible structural consequences of these mutations, we developed a three-dimensional model of full-length, lipid-free human apoA-V. A complex, wide array of impairments was found in each of the three mutants, suggesting that the specific residues affected are critical structural determinants for apoA-V function in lipoprotein metabolism and, therefore, that these APOA5 mutations are a direct cause of hypertriglyceridemia.</p

Predominance of multidrug-resistant bacteria causing urinary tract infections among symptomatic patients in East Africa : a call for action

Background In low- and middle-income countries, antibiotics are often prescribed for patients with symptoms of urinary tract infections (UTIs) without microbiological confirmation. Inappropriate antibiotic use can contribute to antimicrobial resistance (AMR) and the selection of MDR bacteria. Data on antibiotic susceptibility of cultured bacteria are important in drafting empirical treatment guidelines and monitoring resistance trends, which can prevent the spread of AMR. In East Africa, antibiotic susceptibility data are sparse. To fill the gap, this study reports common microorganisms and their susceptibility patterns isolated from patients with UTI-like symptoms in Kenya, Tanzania and Uganda. Within each country, patients were recruited from three sites that were sociodemographically distinct and representative of different populations. Methods UTI was defined by the presence of >104 cfu/mL of one or two uropathogens in mid-stream urine samples. Identification of microorganisms was done using biochemical methods. Antimicrobial susceptibility testing was performed by the Kirby–Bauer disc diffusion assay. MDR bacteria were defined as isolates resistant to at least one agent in three or more classes of antimicrobial agents. Results Microbiologically confirmed UTI was observed in 2653 (35.0%) of the 7583 patients studied. The predominant bacteria were Escherichia coli (37.0%), Staphylococcus spp. (26.3%), Klebsiella spp. (5.8%) and Enterococcus spp. (5.5%). E. coli contributed 982 of the isolates, with an MDR proportion of 52.2%. Staphylococcus spp. contributed 697 of the isolates, with an MDR rate of 60.3%. The overall proportion of MDR bacteria (n = 1153) was 50.9%. Conclusions MDR bacteria are common causes of UTI in patients attending healthcare centres in East African countries, which emphasizes the need for investment in laboratory culture capacity and diagnostic algorithms to improve accuracy of diagnosis that will lead to appropriate antibiotic use to prevent and control AMR.Peer reviewe

Kant, race, and natural history

This article presents a new argument concerning the relation between Kant’s theory of race and aspects of the critical philosophy. It argues that Kant’s treatment of the problem of the systematic unity of nature and knowledge in the Critique of Pure Reason and the Critique of the Power of Judgment can be traced back a methodological problem in the natural history of the period – that of the possibility of a natural system of nature. Kant’s transformation of the methodological problem from natural history into a set of philosophical (and specifically epistemological) problems proceeds by way of the working out of his own problem in natural history – the problem of the natural history of the human races – and specifically the problem of the unity in diversity of the human species, in response to which he develops a theory of race. This theory of race is, further, the first developed model of the use of teleological judgment in Kant’s work. The article thus argues that Kant’s philosophical position on the systematic unity of nature and of knowledge in the first and third Critiques, and his account and defense of teleological judgment, are developed out of problems first articulated in his solution to the problem of the unity in diversity of the human species – that is, in his theory of race. The article does not seek to establish that these aspects of the critical philosophy are therefore racialised. But it does demonstrate, against those who deny its salience to his philosophy, how the problem of the unity in diversity of the human species and Kant’s theory of race is significant for the development of aspects of the critical philosophy and thus contributes to their philosophical problematics