Elastic scattering of intermediate-energy electrons from C_(60) molecules

Experimental and calculated differential cross sections for elastic scattering of electrons by C_(60) molecules at collision energies of 100 to 500 eV are reported. The elastic differential cross sections were measured in a standard crossed-beam apparatus, while the calculations were performed employing the Schwinger multichannel technique at the static-exchange level. Diffraction effects, some due to the overall spherical-cage structure and some to scattering by individual C atoms, are observed in both the measured and calculated cross sections

Hot methane line lists for exoplanet and brown dwarf atmospheres

We present comprehensive experimental line lists of methane (CH4) at high temperatures obtained by recording Fourier transform infrared emission spectra. Calibrated line lists are presented for the temperatures 300 - 1400 degC at twelve 100 degC intervals spanning the 960 - 5000 cm-1 (2.0 - 10.4 microns) region of the infrared. This range encompasses the dyad, pentad and octad regions, i.e., all fundamental vibrational modes along with a number of combination, overtone and hot bands. Using our CH4 spectra, we have estimated empirical lower state energies (Elow in cm-1) and our values have been incorporated into the line lists along with line positions (cm-1) and calibrated line intensities (S' in cm molecule-1). We expect our hot CH4 line lists to find direct application in the modeling of planetary atmospheres and brown dwarfs.Comment: Supplementary material is provided via the Astrophysical Journal referenc

Exploring Halo Substructure with Giant Stars: The Dynamics and Metallicity of the Dwarf Spheroidal in Bootes

We report the results of a spectroscopic study of the Bootes (Boo) dwarf spheroidal (dSph) galaxy carried out with the WIYN telescope and the Hydra multifiber spectrograph. Radial velocities have been measured for 58 Boo candidate stars selected to have magnitudes and colors consistent with its red and asymptotic giant branches. Within the 13' half-light radius, seven members of Boo yield a systemic velocity of V_r=95.6+-3.4 km/s and a velocity dispersion of 6.6+-2.3 km/s. This implies a mass on the order of 1 x 10^7 M_sun, similar to the inferred masses of other Galactic dSphs. Adopting a total Boo luminosity of L=1.8 x 10^4 L_sun to 8.6 x 10^4 L_sun implies M/L ~ 610 to 130, making Boo, the most distorted known Milky Way dwarf galaxy, potentially also the darkest. From the spectra of Boo member stars we estimate its metallicity to be [Fe/H] ~ -2.5, which would make it the most metal poor dSph known to date.Comment: Accepted for publication in ApJ Letter

Teachers' classroom feedback: still trying to get it right

This article examines feedback traditionally given by teachers in schools. Such feedback tends to focus on children's acquisition and retrieval of externally prescribed knowledge which is then assessed against mandated tests. It suggests that, from a sociocultural learning perspective, feedback directed towards such objectives may limit children's social development. In this article, I draw on observation and interview data gathered from a group of 27 9- to 10-year olds in a UK primary school. These data illustrate the children's perceived need to conform to, rather than negotiate, the teacher's feedback comments. They highlight the children's sense that the teacher's feedback relates to school learning but not to their own interests. The article also includes alternative examples of feedback which draw on children's own inquiries and which relate to the social contexts within which, and for whom, they act. It concludes by suggesting that instead of looking for the right answer to the question of what makes teachers' feedback effective in our current classrooms, a more productive question might be how a negotiation can be opened up among teachers and learners themselves, about how teachers' feedback could support children's learning most appropriately

Low-energy electron scattering by tetrahydrofuran

Cross sections for elastic scattering of low-energy electrons by tetrahydrofuran, a prototype for the furanose ring found in the backbone of DNA, have been measured and calculated over a wide energy range, with an emphasis on energies below 6 eV, where previous data are scarce. The measurements employ a thin-aperture version of the relative-flow method, while the calculations employ the Schwinger multichannel method with an extensive treatment of polarization effects. Comparisons with earlier results, both experimental and theoretical, are presented and discussed. A proper accounting for the strong permanent electric dipole of tetrahydrofuran is found to be essential to obtaining reliable cross sections, especially at energies below 5 eV

Collisions of low-energy electrons with isopropanol

We report measured and calculated cross sections for elastic scattering of low-energy electrons by isopropanol (propan-2-ol). The experimental data were obtained using the relative flow technique with helium as the standard gas and a thin aperture as the collimating target gas source, which permits use of this method without the restrictions imposed by the relative flow pressure conditions on helium and the unknown gas. The differential cross sections were measured at energies of 1.5, 2, 3, 5, 6, 8, 10, 15, 20, and 30 eV and for scattering angles from 10∘ to 130∘. The cross sections were computed over the same energy range employing the Schwinger multichannel method in the static-exchange plus polarization approximation. Agreement between theory and experiment is very good. The present data are compared with previously calculated and measured results for n-propanol, the other isomer of C_3H_7OH. Although the integral and momentum transfer cross sections for the isomers are very similar, the differential cross sections show a strong isomeric effect: In contrast to the f-wave behavior seen in scattering by n-propanol, d-wave behavior is observed in the cross sections of isopropanol. These results corroborate our previous observations in electron collisions with isomers of C_4H_9OH

Reduced glycogen availability is associated with increased AMPKα2 activity, nuclear AMPKα2 protein abundance, and GLUT4 mRNA expression in contracting human skeletal muscle

Glycogen availability can influence glucose transporter 4 (GLUT4) expression in skeletal muscle through unknown mechanisms. The multisubstrate enzyme AMP-activated protein kinase (AMPK) has also been shown to play an important role in the regulation of GLUT4 expression in skeletal muscle. During contraction, AMPK [alpha]2 translocates to the nucleus and the activity of this AMPK isoform is enhanced when skeletal muscle glycogen is low. In this study, we investigated if decreased pre-exercise muscle glycogen levels and increased AMPK [alpha]2 activity reduced the association of AMPK with glycogen and increased AMPK [alpha]2 translocation to the nucleus and GLUT4 mRNA expression following exercise. Seven males performed 60 min of exercise at ~70% [VO.sub.2] peak on 2 occasions: either with normal (control) or low (LG) carbohydrate pre-exercise muscle glycogen content. Muscle samples were obtained by needle biopsy before and after exercise. Low muscle glycogen was associated with elevated AMPK [alpha]2 activity and acetyl-CoA carboxylase [beta] phosphorylation, increased translocation of AMPK [alpha]2 to the nucleus, and increased GLUT4 mRNA. Transfection of primary human myotubes with a constitutively active AMPK adenovirus also stimulated GLUT4 mRNA, providing direct evidence of a role of AMPK in regulating GLUT4 expression. We suggest that increased activation of AMPK [alpha]2 under conditions of low muscle glycogen enhances AMPK [alpha]2 nuclear translocation and increases GLUT4 mRNA expression in response to exercise in human skeletal muscle. <br /

Voluntary Counselling, HIV Testing and Adjunctive Cotrimoxazole Reduces Mortality in Tuberculosis Patients in Thyolo, Malawi.

OBJECTIVES: To assess the feasibility and effectiveness of voluntary counselling, HIV testing and adjunctive cotrimoxazole in reducing mortality in a cohort of tuberculosis (TB) patients registered under routine programme conditions in a rural district of Malawi. DESIGN: 'Before' and 'after' cohort study using historical controls. METHODS: Between 1 July 1999 and 30 June 2000 all TB patients were started on standardized anti-TB treatment, and offered voluntary counselling and HIV testing (VCT). Those found to be HIV-positive were offered cotrimoxazole at a dose of 480 mg twice daily, provided there were no contraindications. Side-effects were monitored clinically. End-of-treatment outcomes in this cohort (intervention group) were compared with a cohort registered between 1 July 1998 and 30 June 1999 in whom VCT and cotrimoxazole was not offered (control group). FINDINGS: A total of 1986 patients was registered in the study: 1061 in the intervention group and 925 in the control cohort. In the intervention group, 1019 (96%) patients were counselled pre-test, 964 (91%) underwent HIV testing and 938 (88%) were counselled post-test. The overall HIV-seroprevalence rate was 77%. A total of 693 patients were given cotrimoxazole of whom 14 (2%) manifested minor dermatological reactions. The adjusted relative risk of death in the intervention group compared with the control group was 0.81 (P < 0.001). The number needed to treat with VCT and adjunctive cotrimoxazole to prevent one death during anti-TB treatment was 12.5. INTERPRETATION: This study shows that VCT and adjunctive cotrimoxazole is feasible, safe and reduces mortality rates in TB patients under routine programme conditions

How important is randomisation in a stepped wedge trial?

In cluster randomised trials, randomisation increases internal study validity. If enough clusters are randomised, an unadjusted analysis should be unbiased. If a smaller number of clusters are included, stratified or matched randomisation can increase comparability between trial arms. In addition, an adjusted analysis may be required; nevertheless, randomisation removes the possibility for systematically biased allocation and increases transparency. In stepped wedge trials, clusters are randomised to receive an intervention at different start times ('steps'), and all clusters eventually receive it. In a recent study protocol for a 'modified stepped wedge trial', the investigators considered randomisation of the clusters (hospital wards), but decided against it for ethical and logistical reasons, and under the assumption that it would not add much to the rigour of the evaluation. We show that the benefits of randomisation for cluster randomised trials also apply to stepped wedge trials. The biggest additional issue for stepped wedge trials in relation to parallel cluster randomised trials is the need to control for secular trends in the outcome. Analysis of stepped wedge trials can in theory be based on 'horizontal' or 'vertical' comparisons. Horizontal comparisons are based on measurements taken before and after the intervention is introduced in each cluster, and are unbiased if there are no secular trends. Vertical comparisons are based on outcome measurements from clusters that have switched to the intervention condition and those from clusters that have yet to switch, and are unbiased under randomisation since at any time point, which clusters are in intervention and control conditions will have been determined at random. Secular outcome trends are a possibility in many settings. Many stepped wedge trials are analysed with a mixed model, including a random effect for cluster and fixed effects for time period to account for secular trends, thereby combining both vertical and horizontal comparisons of intervention and control clusters. The importance of randomisation in a stepped wedge trial is that the effects of time can be estimated from the data, and bias from secular trends that would otherwise arise can be controlled for, provided the trends are correctly specified in the model

Coenzyme Q10 in the treatment of mitochondrial disease

Currently, there is a paucity of available treatment strategies for oxidative phosphorylation disorders. Coenzyme Q10 (CoQ10) and related synthetic quinones are the only agents to date that have proven to be beneficial in the treatment of these heterogeneous disorders. The therapeutic efficacy of CoQ10 is not restricted to patients with an underlying CoQ10 deficiency and is thought to result from its ability to restore electron flow in the mitochondrial respiratory chain (MRC) as well as to increase the cellular antioxidant capacity. At present, however, there is no consensus on the appropriate dosage or therapeutic plasma level of CoQ10, and this information will be required before CoQ10 can be utilized effectively in the treatment of mitochondrial disease. The following review will outline our current knowledge on the use of CoQ10 in the treatment of MRC disorders and primary CoQ10 deficiencies. Keyword