On integers nn for which Xn−1X^n-1 has a divisor of every degree

A positive integer $n$ is called $\varphi$-practical if the polynomial $X^n-1$ has a divisor in $\mathbb{Z}[X]$ of every degree up to $n$. In this paper, we show that the count of $\varphi$-practical numbers in $[1, x]$ is asymptotic to $C x/\log x$ for some positive constant $C$ as $x \rightarrow \infty$

Processing, Structure, Properties, and Reliability of Metals for Microsystems

Research on the processing, structure, properties and reliability of metal films and metallic microdevice elements is reviewed. Recent research has demonstrated that inelastic deformation mechanisms of metallic films and microelements are a function of temperature, encapsulation, and dimension. Reduced dimension can lead to strengthening or softening, depending on the temperature and strain rate. These results will help in the analysis and prediction of the stress state of films and microelements as a function of their thermal history. Experimental characterization and modeling of stress evolution during film formation has also been undertaken. New microelectromechanical devices have been developed for in situ measurements of stress during processing, and experiments relating stress and structure evolution are underway for electrodeposition and reactive film formation as well as vapor deposition. Experiments relating current-induced stress evolution (electromigration) to the reliability of Cu based interconnects are also being carried out.Singapore-MIT Alliance (SMA

Research on Polycrystalline Films for Micro- and Nano-Systems

Polycrystalline films are used in a wide array of micro- and nano-scale devices, for electronic, mechanical, magnetic, photonic and chemical functions. Increasingly, the properties, performance, and reliability of films in these systems depend on nano-scale structure. In collaborative research with a number of SMA Fellows, Associates, and students, our group is carrying out research focused on probing, modeling and controlling nano-scale structural evolution during both vapor-phase and solid-phase polycrystalline film formation. In particular, high-sensitivity in-situ and real-time stress measurements are being used to study atomic scale forces and to characterize structure formation and evolution at the nano-scale. In other collaborative research, the affects of controlled structure and multi-film architectures on properties, such as piezoelectric characteristics and electromigration-limited reliability, are being explored. Through these interrelated activities, basic principles of the science and engineering of nano-scale materials are emerging.Singapore-MIT Alliance (SMA

KINETIC, SPECTROSCOPIC AND CHEMICAL MODIFICATION STUDY OF IRON RELEASE FROM TRANSFERRIN; IRON(III) COMPLEXATION TO ADENOSINE TRIPHOSPHATE (ETHOXYFORMIC ANHYDRIDE, LYSINE)

Amino acids other than those that serve as ligands have been found to influence the chemical properties of transferrin iron. The catalytic ability of pyrophosphate to mediate transferrin iron release to a terminal acceptor is largely quenched by modification non-liganded histidine groups on the protein. The first order rate constants of iron release for several partially histidine modified protein samples were measured. A statistical method was employed to establish that one non-liganded histidine per metal binding domain was responsible for the reduction in rate constant. These results imply that the iron mediating chelator, pyrophosphate, binds directly to a histidine residue on the protein during the iron release process. EPR spectroscopic results are consistent with this interpretation. Kinetic and amino acid sequence studies of ovotransferrin and lactoferrin, in addition to human serum transferrin, have allowed the tentative assignment of His-207 in the N-terminal domain and His-535 in the C-terminal domain as the groups responsible for the reduction in rate of iron release. The above concepts have been extended to lysine modified transferrin. Perchlorate induces changes in the EPR spectra and kinetics of iron release in human serum transferrin; similar effects are also induced by lysine modification and found to occur primarily in the C-terminal domain. Furthermore, the labilizing effect of 0.5 M sodium perchlorate on iron in the C-terminal site is largely quenched by lysine modification. The above experiments suggest that the well studied perchlorate effects in transferrin are caused by anion binding at a small number (\u3c15) of lysines, probably located close to the metal. Complexation of iron(III) to adenosine triphosphate (ATP) was also studied to gain insight into the nature of iron-ATP species present at physiological pH. At pH 7.0, mononuclear (metal:ligand \u3c 1:3) and polynuclear (metal:ligand = 2:1 and 4:1) readily form in solution. The mononuclear complexes exhibit a g\u27 = 4.3 EPR signal. (\u2731)P NMR spectra are observed when ATP is present in large excess. The polynuclear (4:1 metal:ligand) complex, although polydisperse in size, has a molecular weight greater than 50,000, indicating cluster formation (\u3c250 iron atoms per cluster). These complexes are EPR silent and give no (\u2731)P NMR spectra consistent with findings for other reported polynuclear iron(III) complexes

Effect of Maternal Melatonin Levels during Late Gestation on the Programming and Metabolic Disposition of Adipose Tissue and Skeletal Muscle in Bovine Offspring

The objectives of this study were to determine: the effects of maternal melatonin (MEL) supplementation during late gestation on the histological and molecular regulation in the Longissimus dorsi (LM) muscle of fetal bovine offspring, composition and gene expression of fetal perirenal (PR) adipose tissue, and LM gene expression in postnatal offspring at birth and d 195 of age. Maternal supplementation of MEL during late gestation resulted in no difference in calf fetal body weight or birth weight. However, at d 195 of age, calves from MEL treated dams had an average body weight increase of 20 kg. Fetal LM weight and length tended to be increased in calves from MEL treated dams. Fetal gene expression of calves from MEL treated dams resulted in: increased LM adenosine monophosphate-activated protein kinase-α (AMPK) and decreased PR adiponectin (ADIPOQ), CCAAT enhancer binding protein alpha (CEBPA), proliferator activated receptor gamma (PPARg), and stearoyl-CoA desaturase (SCD). The improved metabolic status of LM coupled with the decrease in adipogenic gene expression, could result in calves from MEL treated dams having improved lean muscle accretion and reduced overall adiposity during postnatal development

Distribution of anthropogenic mercury in a forested wetland.

Undergraduate Research Exper.As global usage of mercury and methylmercury increases, climate change will impact its distribution and movement in unexpected ways. In wetlands, elemental mercury (Hg) is methylated into its more environmentally toxic form, methylmercury ([CH3Hg+]). The two main sources for anthropogenic mercury are atmospheric deposition and legacy soil mercury. Methylmercury bio-accumulates and causes neurological damage to terrestrial and aquatic organisms. Our research demonstrated that there was mercury within the forested wetland watershed. Also, the analysis suggested that although organic carbon was an indicator for the presence of Hg. However, the best predictor was when horizon mid-point, % C, and δ13C parameters were all considered together. Studying the dynamics and distribution of mercury within wetlands can inform environmental and resource managers on best practices to mitigate these ecological health issues.http://deepblue.lib.umich.edu/bitstream/2027.42/116615/1/Thompson_Carl_REU_2015.pd

Ethnicity, disadvantage and other variables in the analysis of Birmingham longitudinal school attainment datasets

Explaining and responding to inequalities in attainment are significant educational policy challenges in England as elsewhere. Data on four cohorts of Birmingham Local Education Authority (LEA) pupils, each approximately 13,000, were analysed by ethnicity, deprivation, gender and other relevant individual pupil variables. For the four successive cohorts of children, aged five in 1997–2001, analysis shows the attainment trajectory of each ethnic group from Baseline/Foundation Stage Profile (age 5) to GCSE (age 16). The relative constancy over time, the changes from one key stage to the next and the differences within broad ethnic categories argue against simplistic explanations. The ethnicity variable accounts for a relatively small amount of variance in pupil achievement, with the same ethnic subgroups recurrently low attainers. Considering explanatory perspectives on educational inequalities and ethnicity in the light of these data, we conclude that a structuralist perspective offers the best explanation recognising economic exploitation, dominance and oppression at the national and local levels. Notions of institutional racism and Critical Race Theory (CRT) are considered to be inadequate and counter-productive, in part shown by their inability to accommodate the range of attainment levels and educational experience of different ethnic groups. More tellingly, they lack causal explanations relevant to the United Kingdom and deflect attention from the need for sustained effort to reduce poverty and disadvantage as it affects children

Prioritising Health Service Innovation Investments Using Public Preferences: A Discrete Choice Experiment

Background: Prioritising scarce resources for investment in innovation by publically funded health systems is unavoidable. Many healthcare systems wish to foster transparency and accountability in the decisions they make by incorporating the public in decision-making processes. This paper presents a unique conceptual approach exploring the public's preferences for health service innovations by viewing healthcare innovations as 'bundles' of characteristics. This decompositional approach allows policy-makers to compare numerous competing health service innovations without repeatedly administering surveys for specific innovation choices. Methods: A Discrete Choice Experiment (DCE) was used to elicit preferences. Individuals chose from presented innovation options that they believe the UK National Health Service (NHS) should invest the most in. Innovations differed according to: (i) target population; (ii) target age; (iii) implementation time; (iv) uncertainty associated with their likely effects; (v) potential health benefits; and, (vi) cost to a taxpayer. This approach fosters multidimensional decision-making, rather than imposing a single decision criterion (e.g., cost, target age) in prioritisation. Choice data was then analysed using scale-adjusted Latent Class models to investigate variability in preferences and scale and valuations amongst respondents. Results: Three latent classes with considerable heterogeneity in the preferences were present. Each latent class is composed of two consumer subgroups varying in the level of certainty in their choices. All groups preferred scientifically proven innovations, those with potential health benefits that cost less. There were, however, some important differences in their preferences for innovation investment choices: Class-1 (54%) prefers innovations benefitting adults and young people and does not prefer innovations targeting people with 'drug addiction' and 'obesity'. Class- 2 (34%) prefers innovations targeting 'cancer' patients only and has negative preferences for innovations targeting elderly, and Class-3 (12%) prefers spending on elderly and cancer patients the most. Conclusions: DCE can help policy-makers incorporate public preferences for health service innovation investment choices into decision making. The findings provide useful information on the public's valuation and acceptability of potential health service innovations. Such information can be used to guide innovation prioritisation decisions by comparing competing innovation options. The approach in this paper makes, these often implicit and opaque decisions, more transparent and explicit