Spacetime Transformations from a Uniformly Accelerated Frame

We use Generalized Fermi-Walker transport to construct a one-parameter family of inertial frames which are instantaneously comoving to a uniformly accelerated observer. We explain the connection between our approach and that of Mashhoon. We show that our solutions of uniformly accelerated motion have constant acceleration in the comoving frame. Assuming the Weak Hypothesis of Locality, we obtain local spacetime transformations from a uniformly accelerated frame $K'$ to an inertial frame $K$. The spacetime transformations between two uniformly accelerated frames with the same acceleration are Lorentz. We compute the metric at an arbitrary point of a uniformly accelerated frame.Comment: 19 pages, one figure. arXiv admin note: substantial text overlap with arXiv:1105.049

Exploring Climate Change Driven Shifts to Water Rights and Policy Along the Colorado River

The goal of this study is to evaluate the current discussion on how climate driven shifts in hydrology will affect water rights and policy on the upper Colorado River. Global and local temperatures have been increasing steadily. In certain areas of Colorado snowmelt has shifted earlier and is likely to continue to do so. Precipitation as snow is decreasing at certain elevations in the Rocky Mountains. Focusing on water users in the western slope of Colorado, these environmental changes suggest a number of shifts in river hydrology. There will likely be less overall storage as snowpack and possibly earlier more pronounced peak flows. It is expected that earlier flow timing could reduce the ability of senior agriculture users to apply water to crop irrigation. This in turn could increase the value of temporary transfer or fallowing strategies proposed to meet anticipated municipal and industrial water needs. Reduction of agricultural production in certain crops, or shifts to crops that use less water or can be irrigated earlier in the season could also be expected. Junior holders will be affected in potentially different ways. Initially as peak flows shift earlier junior rights holders such as fishing or kayaking industries may see a potential benefit in more water available earlier in the season. However, late season shortages as a result of flow shifts have the potential to exacerbate the value of senior rights. My approach is to combine a review of scientific literature, policy literature, and discussions with professionals and experts on these issues to produce an overview that identifies the most prominent issues and consequences concerning these shifts

Validating reference genes using minimally transformed qpcr data: findings in human cortex and outcomes in schizophrenia

BACKGROUND: It is common practice, when using quantitative real time polymerase chain reaction (qPCR), to normalise levels of mRNA to reference gene mRNA which, by definition, should not vary between tissue, with any disease aetiology or after drug treatments. The complexity of human CNS means it unlikely that any gene could fulfil these criteria. METHODS: To address this issue we measured levels of mRNA for six potential reference genes (GAPDH, PPIA, SNCA, NOL9, TFB1M and SKP1) in three cortical regions (Brodmann's areas (BA) 8, 9 and 44) from 30 subjects with schizophrenia and 30 age and sex matched controls. We used a structured statistical approach to examine the characteristics of these data to determine their suitability as reference genes. We also analysed our data using reference genes selected by rank as defined using the average of the standard deviation of pair-gene ΔCt and the BestKeeper, NormFinder and geNorm algorithms to determine if they suggested the same reference genes. RESULTS: Our minimally derived data showed that levels of mRNA for all of the six genes varied between cortical regions and therefore no gene fulfilled the absolute requirements for use as reference genes. As levels of some mRNA for some genes did not vary with diagnoses within a cortical region from subjects with schizophrenia compared to controls, we normalised levels of mRNA for all the other genes to mRNA for one, two or three reference genes in each cortical region. This showed that using the geometric mean of at least two reference genes gave more reproducible results. Finally, using the reference gene ranking protocols the average of the standard deviation of pair-gene ΔCt, BestKeeper, NormFinder and geNorm we showed that these approaches ranked potential reference genes differently. We then showed that outcomes of comparing data from subjects with schizophrenia and controls varied depending on the reference genes chosen. CONCLUSIONS: Our data shows that the selection of reference genes is a significant component of qPCR study design and therefore the process by which reference genes are selected must be clearly listed as a potential confound in studying gene expression in human CNS. This should include showing that, using minimally derived qPCR data, levels of mRNA for proposed reference genes does not vary with variables such as diagnoses and CNS region

Improvement of Pheromone Trapping in Low Density Populations of \u3ci\u3eChoristoneura Pinus Pinus\u3c/i\u3e (Lepidoptera: Tortricidae)

Pheromone baited bucket traps (e.g., Multipher) are popular as a monitoring tool for the jack pine budworm, Choristoneura pinus pinus Freeman (Lepidoptera: Tortricidae), in Canada. However, there is no evidence to support their use when budworm populations are low. We therefore evaluated the capture rate of bucket traps at two placement heights (2 vs 6 m) in two jack pine forests in 2011, having low (≤5 fifth instars per mfoliated branch length) budworm populations. Compared to wing traps (e.g., Pherocon 1C), the trap design used initially to evaluate efficacy of the C. pinus pheromone, bucket traps caught fewer C. pinus and capture rates of both trap designs did not differ significantly between the two heights tested. Loss of bucket traps at 2 m, due to black bears, suggested that higher placement of traps was warranted to maintain the integrity of the array. However, wing traps are recommended due to their ability to consistently catch more moths when C. pinus populations are low

Covariant Uniform Acceleration

We show that standard Relativistic Dynamics Equation F=dp/d\tau is only partially covariant. To achieve full Lorentz covariance, we replace the four-force F by a rank 2 antisymmetric tensor acting on the four-velocity. By taking this tensor to be constant, we obtain a covariant definition of uniformly accelerated motion. We compute explicit solutions for uniformly accelerated motion which are divided into four types: null, linear, rotational, and general. For null acceleration, the worldline is cubic in the time. Linear acceleration covariantly extends 1D hyperbolic motion, while rotational acceleration covariantly extends pure rotational motion. We use Generalized Fermi-Walker transport to construct a uniformly accelerated family of inertial frames which are instantaneously comoving to a uniformly accelerated observer. We explain the connection between our approach and that of Mashhoon. We show that our solutions of uniformly accelerated motion have constant acceleration in the comoving frame. Assuming the Weak Hypothesis of Locality, we obtain local spacetime transformations from a uniformly accelerated frame K' to an inertial frame K. The spacetime transformations between two uniformly accelerated frames with the same acceleration are Lorentz. We compute the metric at an arbitrary point of a uniformly accelerated frame. We obtain velocity and acceleration transformations from a uniformly accelerated system K' to an inertial frame K. We derive the general formula for the time dilation between accelerated clocks. We obtain a formula for the angular velocity of a uniformly accelerated object. Every rest point of K' is uniformly accelerated, and its acceleration is a function of the observer's acceleration and its position. We obtain an interpretation of the Lorentz-Abraham-Dirac equation as an acceleration transformation from K' to K.Comment: 36 page

Epistemic and social scripts in computer-supported collaborative learning

Collaborative learning in computer-supported learning environments typically means that learners work on tasks together, discussing their individual perspectives via text-based media or videoconferencing, and consequently acquire knowledge. Collaborative learning, however, is often sub-optimal with respect to how learners work on the concepts that are supposed to be learned and how learners interact with each other. One possibility to improve collaborative learning environments is to conceptualize epistemic scripts, which specify how learners work on a given task, and social scripts, which structure how learners interact with each other. In this contribution, two studies will be reported that investigated the effects of epistemic and social scripts in a text-based computer-supported learning environment and in a videoconferencing learning environment in order to foster the individual acquisition of knowledge. In each study the factors ‘epistemic script’ and ‘social script’ have been independently varied in a 2×2-factorial design. 182 university students of Educational Science participated in these two studies. Results of both studies show that social scripts can be substantially beneficial with respect to the individual acquisition of knowledge, whereas epistemic scripts apparently do not to lead to the expected effects

Stainless steel made to rust: a robust water-splitting catalyst with benchmark characteristics

The oxygen evolution reaction (OER) is known as the efficiency-limiting step for the electrochemical cleavage of water mainly due to the large overpotentials commonly used materials on the anode side cause. Since Ni–Fe oxides reduce overpotentials occurring in the OER dramatically they are regarded as anode materials of choice for the electrocatalytically driven water-splitting reaction. We herewith show that a straightforward surface modification carried out with AISI 304, a general purpose austenitic stainless steel, very likely, based upon a dissolution mechanism, to result in the formation of an ultra-thin layer consisting of Ni, Fe oxide with a purity >99%. The Ni enriched thin layer firmly attached to the steel substrate is responsible for the unusual highly efficient anodic conversion of water into oxygen as demonstrated by the low overpotential of 212 mV at 12 mA cm−2 current density in 1 M KOH, 269.2 mV at 10 mA cm−2 current density in 0.1 M KOH respectively. The Ni, Fe-oxide layer formed on the steel creates a stable outer sphere, and the surface oxidized steel samples proved to be inert against longer operating times (>150 ks) in alkaline medium. In addition Faradaic efficiency measurements performed through chronopotentiometry revealed a charge to oxygen conversion close to 100%, thus underpinning the conclusion that no “inner oxidation” based on further oxidation of the metal matrix below the oxide layer occurs. These key figures achieved with an almost unrivalled-inexpensive and unrivalled-accessible material, are among the best ever presented activity characteristics for the anodic water-splitting reaction at pH 13

Angry responses to infant challenges: parent, marital, and child genetic factors associated with harsh parenting

This study examined genetic and environmental influences on harsh parenting of 9-month-olds. We examined whether positive child-, parent-, and family-level characteristics were associated with harsh parenting in addition to negative characteristics. We were particularly interested in examining evocative gene-environment correlation (rGE) by testing the effect of birth parent temperament on adoptive parents’ harsh parenting. Additionally, we examined associations among adoptive parents’ own temperaments, their marital relationship quality, and harsh parenting. Adoptive fathers’ (but not adoptive mothers’) harsh parenting was inversely related to an index of birth mother positive temperament (reward dependence), indicating evocative rGE. Higher marital quality was associated with less harsh parenting, but only for adoptive fathers. Adoptive parents’ negative temperamental characteristics (harm avoidance) were related to hostile parenting. Findings suggest the importance of enhancing positive family characteristics in addition to mitigating negative characteristics, as well as engaging multiple levels of the family system to prevent harsh parenting. Children have the potential to evoke strong positive and negative affective responses from parents, which then influence and organize caregiving behavior (Dix, 1991). All young children demonstrate challenging behaviors, such as prolonged crying that may be difficult to soothe, uncooperativeness with bathing or dressing, or difficulty with eating or sleeping. The degree to which parental negative emotion is evoked by these challenges and expressed in interactions with children is often characterized as harsh or overreactive parenting. Harsh parenting is a function of a complex interplay of risk and protective factors that operate at multiple levels of the family system (i.e., characteristics of the parent, child, and family environment; Belsky, 1984; Boivin et al., 2005; DiLalla & Bishop, 1996; Neiderhiser et al., 2004, 2007; Towers, Spotts, & Neiderhiser, 2002). The long-term maladaptive developmental outcomes associated with harsh, negative parenting during infancy (Bayer, Ukoumunne, Mathers, Wake, Abdi, & Hiscock, 2012; Bradley & Corwyn, 2008; Lorber & Egeland, 2009) underscore the need for improved understanding of risk and protective factors associated with early harsh parenting. The current study aims to extend on the research on harsh parenting in infancy in two ways. First, although risk factors for early harsh parenting are well documented, we know little about factors that buffer parents from harsh parenting during infancy; this study examines independent and differential effects of positive and negative characteristics on harsh parenting. Second, although interest in child effects on parenting, including harsh parenting, has been present in the field for decades (Bell, 1979; Bell & Chapman, 1986; Rutter et al., 1997) we know very little about the degree to which the effects found in the literature truly reflect evocative effects of infants’ genetically influenced characteristics. The current study used an adoption design to test the hypothesis that genetically influenced temperamental characteristics of 9-month-olds would influence adoptive parents’ harsh parenting. Previous research has identified many correlates of harsh parenting, including negative characteristics of the parent (e.g., maternal depression; Lovejoy, Graczyk, O’Hare, & Neuman, 2000), family (e.g., marital hostility, Rhoades et al., 2011), and child (e.g., difficult temperament, Plomin, Loehlin & DeFries, 1985; poor regulation, Bridgett et al., 2009). Previous research has identified risk factors for harsh parenting, but very little is known about how positive parent, child, and family characteristics might mitigate it. For example, a positive marital relationship could buffer the impact of high levels of depressive symptoms on parenting, and thus have implications for prevention and intervention efforts. The current study examined positive and negative parent, child, and family factors in association with harsh parenting. A second emphasis centered on understanding the role of infants’ genetically influenced characteristics on harsh parenting. Much of the previous work on child effects on parenting has examined child temperament. In general, child positivity is related to positive parenting, while child negativity is related to negative parenting (Putnam, Sanson, & Rothbart, 2002; Wilson & Durbin, 2012). However, the general lack of genetically sensitive designs in this research makes it impossible to determine whether these associations exist because (1) harsh parenting leads to negative child characteristics, (2) specific child characteristics evoke harsh parenting (evocative gene-environment correlation, rGE; Plomin, Loehlin & DeFries, 1977; Scarr & McCartney, 1983) or (3) children and parents share genes that contribute to both parenting and temperament (passive gene-environment correlation). Therefore, genetically-sensitive research designs are needed to disentangle these influences to understand specific mechanisms underlying relations between child characteristics and parent behavior