Why are They Moving Away? Comparing Attachment to Place in the Great Plains to the Rest of the Nation

We combine a telephone survey of working-aged adults in the continental US with Census 2000 county and zip code tabulation area data to explore attachment to place. Using results of the 2000 US Census, we define cultural and economic regions. Our modified “Great Plains” area is that portion of the region that is experiencing population decline. We explore how attachment to place is different between the Great Plains and other regions of the US. Our measure of attachment to place is a question on the amount of additional income respondents would require to move to a similar community 500 miles away. We identify three respondent groups: unconditional migrants, conditional migrants, and unconditionally rooted. Basic tabulations and regression analysis reveal differences between the Great Plains and other regions. Natural amenities present in the community appear to play a role in shaping respondent attitudes towards relocation

Unraveling the role of protein dynamics in dihydrofolate reductase catalysis

Protein dynamics have controversially been proposed to be at the heart of enzyme catalysis, but identification and analysis of dynamical effects in enzyme-catalyzed reactions have proved very challenging. Here, we tackle this question by comparing an enzyme with its heavy (15N, 13C, 2H substituted) counterpart, providing a subtle probe of dynamics. The crucial hydride transfer step of the reaction (the chemical step) occurs more slowly in the heavy enzyme. A combination of experimental results, quantum mechanics/molecular mechanics simulations, and theoretical analyses identify the origins of the observed differences in reactivity. The generally slightly slower reaction in the heavy enzyme reflects differences in environmental coupling to the hydride transfer step. Importantly, the barrier and contribution of quantum tunneling are not affected, indicating no significant role for “promoting motions” in driving tunneling or modulating the barrier. The chemical step is slower in the heavy enzyme because protein motions coupled to the reaction coordinate are slower. The fact that the heavy enzyme is only slightly less active than its light counterpart shows that protein dynamics have a small, but measurable, effect on the chemical reaction rate

Development of a model pile for heat transfer experiments in the centrifuge

Conventional energy piles use embedded plastic pipes to circulate a fluid through solid concrete which enables transfer of heat into, or out of, the ground as required. Such piles are relatively low efficiency owing to the poor conductivity of the concrete in which the pipes are embedded. They are also known to be susceptible to damage during construction and their adoption as a sustainable energy source has, as a result, been limited. A novel method of heat transfer, which is much less susceptible to damage during construction, and has been found in field trials to be more energy efficient, exploits the significantly higher conductivity of water in a rotary augured hollow, cast in-situ, or precast pile. In such a pile the plastic pipes are placed in the water filled central void of the pile. Such an arrangement will lead to the ground around the pile experiencing a lower range of temperature variation compared with standard energy piles and the influence of this effect on pile capacity will be explored. In order to model multiple cycles of temperature variation to which the ground around a prototype pile may be subjected it is necessary design experimental apparatus that is capable of rapid heating and cooling and with high thermal conductivity materials. The paper will describe the design of a model pile which incorporates an immersed heating element capable of bringing the pile temperature to a specific maximum value and a means of quickly purging the heated water to return the pile temperature to the desired minimum value whilst the pile carries a constant axial load in the centrifuge

DART Mass spectrometry as a potential tool for the differentiation of captive-bred and wild lion bones.

In recent years lion bones have been legally traded internationally to Asian markets from captive bred sources in South Africa. There are also indications of increasing instances of illegal international trade in wild lion bones. The existence of parallel captive and wild supplies of lion bone are a cause of law enforcement concern regarding the potential for the laundering of illegally sourced bones through legal trade, and present a problem for the assessment of the conservation impact of wild lion bone trade due to the difficulty of determining what market-share wild and captive-bred lion bones account for. Captive-bred and wild lion bone are visually indistinguishable and no reliable method currently exists for distinguishing them. We present a preliminary study that explores the use of DART mass spectrometry as a method to differentiate between captive-bred and wild lion bones. We find that DART is able to differentiate between a batch of captive-bred South African lion bone and a batch of wild lion bone and suggest that DART mass spectrometry shows strong potential as a tool for the regulation and investigation of lion bone trade. Further testing is needed to prove the suitability of this technique. Therefore, we suggest that further research focuses on testing the capability of DART to differentiate between contemporary wild and captive-bred lion bone originating from South Africa, and attempts to identify chemical markers in bone that can be used as indicators of captive-bred origin

Comparison of two different models for pile thermal response test interpretation

Thermal response tests (TRTs) are regularly used to characterise the thermal resistance of borehole heat exchangers and to assess the thermal conductivity of the surrounding ground. It is becoming common to apply the same in situ testing technique to pile heat exchangers, despite international guidance suggesting that TRTs should be limited to hole diameters of 152 mm (6 in.). This size restriction arises from the increased thermal inertia of larger diameter heat exchangers, which invalidates the assumption of a steady state within the concrete needed to interpret the test data by traditional line source analysis techniques. However, new methods of analysis for pile heat exchangers have recently been developed that take account of the transient behaviour of the pile concrete. This paper applies these new methods to data from a multi-stage TRT conducted on a small diameter test pile. The thermal conductivity and thermal resistance determined using this method are then compared with those from traditional analytical approaches based on a line source analysis. Differences between the approaches are discussed, along with the observation that the thermal resistance may not be constant over the different test stages

Transient x-ray diffraction used to diagnose shock compressed Si crystals on the Nova laser

Transient x-ray diffraction is used to record time-resolved information about the shock compression of materials. This technique has been applied on Nova shock experiments driven using a hohlraum x-ray drive. Data were recorded from the shock release at the free surface of a Si crystal, as well as from Si at an embedded ablator/Si interface. Modeling has been done to simulate the diffraction data incorporating the strained crystal rocking curves and Bragg diffraction efficiencies. Examples of the data and post-processed simulations are presented

Pulsar kicks from neutrino oscillations

Neutrino oscillations in a core-collapse supernova may be responsible for the observed rapid motions of pulsars. Given the present bounds on the neutrino masses, the pulsar kicks require a sterile neutrino with mass 2-20 keV and a small mixing with active neutrinos. The same particle can be the cosmological dark matter. Its existence can be confirmed the by the X-ray telescopes if they detect a 1-10 keV photon line from the decays of the relic sterile neutrinos. In addition, one may be able to detect gravity waves from a pulsar being accelerated by neutrinos in the event of a nearby supernova.Comment: invited review article to appear in Int. J. Mod. Phys. (21 pages, 6 figures

Classic and spatial shift-share analysis of state-level employment change in Brazil

This paper combines classic and spatial shift-share decompositions of 1981 to 2006 employment change across the 27 states of Brazil. The classic shift-share method shows higher employment growth rates for underdeveloped regions that are due to an advantageous industry-mix and also due to additional job creation, commonly referred to as the competitive effect. Alternative decompositions proposed in the literature do not change this broad conclusion. Further examination employing exploratory spatial data analysis (ESDA) shows spatial correlation of both the industry-mix and the competitive effects. Considering that until the 1960s economic activities were more concentrated in southern regions of Brazil than they are nowadays, these results support beta convergence theories but also find evidence of agglomeration effects. Additionally, a very simple spatial decomposition is proposed that accounts for the spatially-weighted growth of surrounding states. Favourable growth in northern and centre-western states is basically associated with those states’ strengths in potential spatial spillover effect and in spatial competitive effect

Thermal performance of thermoactive continuous flight auger piles

Foundation piles are being increasingly equipped with heat exchangers to efficiently harvest shallow geothermal energy. For buildings in urban areas, continuous flight auger (CFA) piles are common owing to their speed, cost-efficiency and low noise levels. To construct a thermoactive CFA pile usually requires separate central installation of the heat exchanger. However, the energy performance of this type of pile has not been investigated systematically, with most studies focused on rotary piles where the heat exchanger is attached to the reinforcing cage. In this work, insights are provided about the main influences on the energy efficiency of thermoactive CFA piles, with a focus on the implications of using CFA construction techniques rather than rotary boring. An innovative three-dimensional numerical model, able to capture the different aspects of transient heat transfer, is employed together with analytical methods to evaluate the transient and steady-state behaviour of energy piles in a number of design situations. Attention is given to understanding the role of possible pipe-to-pipe interaction, which cannot be systematically investigated with standard methods. Finally, practical guidelines on the optimal choice of design parameters to maximise the energy efficiency of CFA piles, without altering the geotechnical arrangements, are provided

Thermal Adaptation of Dihydrofolate Reductase from the Moderate ThermophileGeobacillus stearothermophilus

The thermal melting temperature of dihydrofolate reductase from Geobacillus stearothermophilus (BsDHFR) is 30 °C higher than that of its homologue from the psychrophile Moritella profunda. Additional proline residues in the loop regions of BsDHFR have been proposed to enhance the thermostability of BsDHFR, but site-directed mutagenesis studies reveal that these proline residues contribute only minimally. Instead, the high thermal stability of BsDHFR is partly due to removal of water-accessible thermolabile residues such as glutamine and methionine, which are prone to hydrolysis or oxidation at high temperatures. The extra thermostability of BsDHFR can be obtained by ligand binding, or in the presence of salts or cosolvents such as glycerol and sucrose. The sum of all these incremental factors allows BsDHFR to function efficiently in the natural habitat of G. stearothermophilus, which is characterized by temperatures that can reach 75 °C