408 research outputs found
Interdistrict and Charter School Mobility in Arizona: Understanding the Dynamics of Public School Choice
We investigate the mobility patterns of elementary students enrolled in Arizona’s traditional public school districts and charter schools. We address interdistrict and charter school mobility simultaneously. Most student movement is interdistrict or between school districts. In Arizona, interdistrict mobility has played a greater role in creating and sustaining the “educational market” than charter schools. There is also a substantial amount of student movement from charter schools to school districts. Regression analyses suggested that the relationship between demographic and achievement variables and the different types of student mobility differed across the two sectors. We also document regional differences in mobility patterns, which indicate that education markets vary considerably across and even within local contexts
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NEPC Review: From Surviving to Thriving: K-12 Choice and Opportunity for Rural Texas Students and Teachers (The Heritage Foundation, August 2023)
A Heritage Foundation report claims increased competition has improved academic achievement in Arizona’s rural public schools and that similar policies will be good for rural Texas. However, this report overstates the similarities between Arizona and Texas, ignores relevant research literature, and presents simplistic and inaccurate analyses to support its claims. By addressing a narrow set of possible benefits of school choice, it also overlooks issues related to fiscal impacts for district schools, segregation, and exclusionary practices for students who require specialized services in schools. The report is an exercise in advocacy for expanding school choice policies, and its usefulness as a guide for policy and practice is minimal.</p
Hit-to-lead and lead optimization binding free energy calculations for G protein-coupled receptors
We apply the hit-to-lead ESMACS (enhanced sampling of molecular dynamics with approximation of continuum solvent) and lead-optimization TIES (thermodynamic integration with enhanced sampling) methods to compute the binding free energies of a series of ligands at the A1 and A2A adenosine receptors, members of a subclass of the GPCR (G protein-coupled receptor) superfamily. Our predicted binding free energies, calculated using ESMACS, show a good correlation with previously reported experimental values of the ligands studied. Relative binding free energies, calculated using TIES, accurately predict experimentally determined values within a mean absolute error of approximately 1 kcal mol−1. Our methodology may be applied widely within the GPCR superfamily and to other small molecule–receptor protein systems
A Dental Student Perspective on the Impacts of an Inter-professional Engagement Module
Community engagement, defined as the process of getting communities involved in decisions that affect them (NICE, 2008), is paramount to the development and governance of services and activities that promote health and target inequalities (Buck, Baylis, Dougall, & Robertson, 2018; NICE, 2008). The inter-professional engagement module is an integral part of the curriculum of Peninsula Dental School, University of Plymouth, United Kingdom. It enables second-year undergraduate dental and dental therapy and hygiene students to develop and deliver an oral health intervention targeted at disadvantaged groups in the community. These groups commonly experience higher levels of dental disease (Public Health England, 2018; Office of the Director of Public Health, Plymouth City Council, 2018). As part of this module, we, a second-year group of undergraduate dental students, worked alongside the Family Intensive Intervention Project (FIIP) and its beneficiaries to improve vulnerable families’ awareness of oral and general health, and to break down barriers toward accessing dental care. FIIP provides holistic support to families with complex needs who may have difficulties with issues such as substance misuse, mental health and evidence of neglectful parenting (W. Kirby, personal communication, 2018).</jats:p
Positive parenting for positive parents: HIV/AIDS, poverty, caregiver depression, child behavior, and parenting in South Africa
Families affected by HIV/AIDS in the developing world experience higher risks of psychosocial problems than nonaffected families. Positive parenting behavior may buffer against the negative impact of child AIDS-orphanhood and caregiver AIDS-sickness on child well-being. Although there is substantial literature regarding the predictors of parenting behavior in Western populations, there is insufficient evidence on HIV/AIDS as a risk factor for poor parenting in low- and middle-income countries. This paper examines the relationship between HIV/AIDS and positive parenting by comparing HIV/AIDS-affected and nonaffected caregiver-child dyads (n=2477) from a cross-sectional survey in KwaZulu-Natal, South Africa (27.7% AIDS-ill caregivers; 7.4% child AIDS-orphanhood). Multiple mediation analyses tested an ecological model with poverty, caregiver depression, perceived social support, and child behavior problems as potential mediators of the association of HIV/AIDS with positive parenting. Results indicate that familial HIV/AIDS's association to reduced positive parenting was consistent with mediation by poverty, caregiver depression, and child behavior problems. Parenting interventions that situate positive parenting within a wider ecological framework by improving child behavior problems and caregiver depression may buffer against risks for poor child mental and physical health outcomes in families affected by HIV/AIDS and poverty
Papillomavirus E1 helicase assembly maintains an asymmetric state in the absence of DNA and nucleotide cofactors
Concerted, stochastic and sequential mechanisms of action have been proposed for different hexameric AAA+ molecular motors. Here we report the crystal structure of the E1 helicase from bovine papillomavirus, where asymmetric assembly is for the first time observed in the absence of nucleotide cofactors and DNA. Surprisingly, the ATP-binding sites adopt specific conformations linked to positional changes in the DNA-binding hairpins, which follow a wave-like trajectory, as observed previously in the E1/DNA/ADP complex. The protein's assembly thus maintains such an asymmetric state in the absence of DNA and nucleotide cofactors, allowing consideration of the E1 helicase action as the propagation of a conformational wave around the protein ring. The data imply that the wave's propagation within the AAA+ domains is not necessarily coupled with a strictly sequential hydrolysis of ATP. Since a single ATP hydrolysis event would affect the whole hexamer, such events may simply serve to rectify the direction of the wave's motion
Variation in enteric methane emissions among cows on commercial dairy farms
Methane (CH4) emissions by dairy cows vary with feed intake and diet composition. Even when fed on the same diet at the same intake, however, variation between cows in CH4 emissions can be substantial. The extent of variation in CH4 emissions among dairy cows on commercial farms is unknown, but developments in methodology now permit quantification of CH4 emissions by individual cows under commercial conditions. The aim of this research was to assess variation among cows in emissions of eructed CH4 during milking on commercial dairy farms. Enteric CH4 emissions from 1,964 individual cows across 21 farms were measured for at least 7 days per cow using CH4 analysers at robotic milking stations. Cows were predominantly of Holstein Friesian breed and remained on the same feeding systems during sampling. Effects of explanatory variables on average CH4 emissions per individual cow were assessed by fitting a linear mixed model. Significant effects were found for week of lactation, daily milk yield and farm. The effect of milk yield on CH4 emissions varied among farms. Considerable variation in CH4 emissions was observed among cows after adjusting for fixed and random effects, with the coefficient of variation ranging from 22 to 67% within farms. This study confirms that enteric CH4 emissions vary among cows on commercial farms, suggesting that there is considerable scope for selecting individual cows and management systems with reduced emissions
A two-domain elevator mechanism for sodium/proton antiport
Sodium/proton (Na+/H+) antiporters, located at the plasma membrane in every cell, are vital for cell homeostasis1. In humans, their dysfunction has been linked to diseases, such as hypertension, heart failure and epilepsy, and they are well-established drug targets2. The best understood model system for Na+/H+ antiport is NhaA from Escherichia coli1, 3, for which both electron microscopy and crystal structures are available4, 5, 6. NhaA is made up of two distinct domains: a core domain and a dimerization domain. In the NhaA crystal structure a cavity is located between the two domains, providing access to the ion-binding site from the inward-facing surface of the protein1, 4. Like many Na+/H+ antiporters, the activity of NhaA is regulated by pH, only becoming active above pH 6.5, at which point a conformational change is thought to occur7. The only reported NhaA crystal structure so far is of the low pH inactivated form4. Here we describe the active-state structure of a Na+/H+ antiporter, NapA from Thermus thermophilus, at 3 Å resolution, solved from crystals grown at pH 7.8. In the NapA structure, the core and dimerization domains are in different positions to those seen in NhaA, and a negatively charged cavity has now opened to the outside. The extracellular cavity allows access to a strictly conserved aspartate residue thought to coordinate ion binding1, 8, 9 directly, a role supported here by molecular dynamics simulations. To alternate access to this ion-binding site, however, requires a surprisingly large rotation of the core domain, some 20° against the dimerization interface. We conclude that despite their fast transport rates of up to 1,500 ions per second3, Na+/H+ antiporters operate by a two-domain rocking bundle model, revealing themes relevant to secondary-active transporters in general
Randomised controlled trial to evaluate the effect of foot trimming before and after first calving on subsequent lameness episodes and productivity in dairy heifers
The objective of this study was to assess both independent and combined effects of routine foot trimming of heifers at 3 weeks pre-calving and 100 days post calving on the first lactation lameness and lactation productivity. A total of 419 pre-calving dairy heifers were recruited from one heifer rearing operation over a 10-month period. Heifers were randomly allocated into one of four foot trimming regimens; pre-calving foot trim and post-calving lameness score (Group TL), pre-calving lameness score and post-calving foot trim (Group LT), pre-calving foot trim and post-calving foot trim (Group TT), and pre-calving lameness score and post-calving lameness score (Group LL, control group). All heifers were scored for lameness at 24 biweekly time points for 1 year following calving, and first lactation milk production data were collected.
Following calving, 172/419 (41.1%) of heifers became lame during the study (period prevalence), with lameness prevalence at each time-point following calving ranging from 48/392 (12.2%) at 29–42 days post-calving to 4/379 (1.1%) between 295 and 383 days after calving. The effects of the four treatment groups were not significantly different from each other for overall lameness period prevalence, biweekly lameness point prevalence, time to first lameness event, type of foot lesion identified at dry off claw trimming, or the 4% fat corrected 305-day milk yield. However, increased odds lameness was significantly associated with a pre-calving trim alone (P = 0.044) compared to the reference group LL. The odds of heifer lameness were highest between 0 and 6 weeks post-partum, and heifer farm destination was significantly associated with lameness (OR 2.24), suggesting that even at high standard facilities, environment and management systems have more effect on heifer foot health than trimming
Structural and biochemical characterization of the exopolysaccharide deacetylase Agd3 required for Aspergillus fumigatus biofilm formation
The exopolysaccharide galactosaminogalactan (GAG) is an important virulence factor of the fungal pathogen Aspergillus fumigatus. Deletion of a gene encoding a putative deacetylase, Agd3, leads to defects in GAG deacetylation, biofilm formation, and virulence. Here, we show that Agd3 deacetylates GAG in a metal-dependent manner, and is the founding member of carbohydrate esterase family CE18. The active site is formed by four catalytic motifs that are essential for activity. The structure of Agd3 includes an elongated substrate-binding cleft formed by a carbohydrate binding module (CBM) that is the founding member of CBM family 87. Agd3 homologues are encoded in previously unidentified putative bacterial exopolysaccharide biosynthetic operons and in other fungal genomes. The exopolysaccharide galactosaminogalactan (GAG) is an important virulence factor of the fungal pathogen Aspergillus fumigatus. Here, the authors study an A. fumigatus enzyme that deacetylates GAG in a metal-dependent manner and constitutes a founding member of a new carbohydrate esterase family.Bio-organic Synthesi
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