Twin Engines of Growth

We develop an endogenous growth model in which new technology and new skills are bounded complements -- they complement each other to a point, but beyond this the impact of each factor is constrained by the level of the other. As a result, both technological progress and human capital accumulation are necessary for sustained productivity growth, but neither alone is sufficient. Rapid technological progress generates increased returns to education and encourages each generation to spend more time at school. Rapid human capital accumulation increases the feasability and profitability of innovation and encourages the private business sector to allocate more resources towards R&D. Our model has important implications for the effectiveness of alternative growth-promoting policies, for the interpretation of the empirical relationship between growth and schooling, and for the relationship between growth and intergenerational wage dispersion. Nous développons un modèle de croissance endogène dans lequel la nouvelle technologie et les nouvelles compétences sont des compléments limités -- elles se complémentent jusqu'à un certain point, au delà duquel l'impact de chaque facteur est contraint par le niveau de l'autre. Alors, le progrès technologique et l'accumulation de capital humain sont nécessaires les deux pour une croissance soutenue de la productivité, mais aucun n'est suffisant seul. Un progrès technologique rapide génère des rendements croissants de l'éducation et encourage chaque génération à consacrer plus de temps à l'école. Une accumulation rapide de capital humain accroît la faisabilité et la profitabilité de l'innovation et encourage le secteur privé à allouer plus de ressources en recherche et développement. Notre modèle a des implications importantes pour la relation empirique entre croissance et éducation, et pour la relation entre croissance et dispersion intergénérationnelle des salaires.Endogenous technological change, endogenous human capital accumulation, minimum skill requirements, bounded complementarity

Twin Engines of Growth

We develop an endogenous growth model in which new technology and new skills are bounded complements they complement each other up to a point, but beyond this the impact of each factor is constrained by the level of the other. As a result, both technological progress and human capital accumulation are necessary for sustained productivity growth, but neither alone is sufficient. Rapid technological progress generates increased returns to education and encourages each generation to spend more time in school. Rapid human capital accumulation increases the feasibility and profitability of innovation and encourages the private business sector to allocate more resources towards R&D. Our model has important implications for the effectiveness of alternative growth promoting policies, for the interpretation of the empirical relationship between growth and schooling, and for the relationship between growth and intergenerational wage dispersion. Keywords: Endogenous technological change, endogenous human capital accumulation, minimum skill requirements, bounded complementarity.Endogenous technological change, endogenous human capital accumulation, minimum skill requirements, bounded complementarity.

Perturbative Part of the Non-Singlet Structure Function F_2 in the Large-N_F Limit

We have calculated $\bar{MS}$ Wilson coefficients and anomalous dimensions for the non-singlet part of the structure function F_2 in the large-N_F limit. Our result agrees with exact two and three loop calculations and gives the leading N_F dependence of the perturbative non-singlet Wilson coefficients to all orders in $\alpha_S$.Comment: 11 pages, including one figur

Electric Dipole Moment Constraints on Phases in the Constrained MSSM

We consider constraints on \cp-violating phases in the Constrained Minimal Supersymmetric Standard Model. We find that by combining cosmological limits on gaugino masses with experimental bounds on the neutron and electron electric dipole moments, we can constrain the phase of the Higgs mixing mass $\mu$ to be $|\theta_\mu| < \pi/10$, independent of choices of the other mass parameters in the model. The other \cp-violating phase $\theta_A$ is essentially unconstrained.Comment: 10 pages in LaTeX + 3 postscript figures, uses epsf.st

Update on the pathogenic potential and treatment options for Blastocystis sp

Although Blastocystis is one of the most common enteric parasites, there is still much controversy surrounding the pathogenicity and potential treatment options for this parasite. In this review we look at the evidence supporting Blastocystis as an intestinal pathogen as shown by numerous case studies and several in vivo studies and the evidence against. We describe the chronic nature of some infections and show the role of Blastocystis in immunocompromised patients and the relationship between irritable bowel syndrome and Blastocystis infection. There have been several studies that have suggested that pathogenicity may be subtype related. Metronidazole is the most widely accepted treatment for Blastocystis but several cases of treatment failure and resistance have been described. Other treatment options which have been suggested include paromomycin and trimethroprim- sulfamethoxazole. © 2014 Roberts et al.; licensee BioMed Central Ltd

Lyman-alpha Emission from a Luminous z=8.68 Galaxy: Implications for Galaxies as Tracers of Cosmic Reionization

We report the discovery of Lyman-alpha emission (Ly$\alpha$) in the bright galaxy EGSY-2008532660 (hereafter EGSY8p7) using the MOSFIRE spectrograph at the Keck Observatory. First reported by Roberts-Borsani et al. (2015), it was selected for spectroscopic observations because of its photometric redshift ($z_{phot}=8.57^{+0.22}_{-0.43}$), apparent brightness (H$_{160}=25.26\pm0.09$) and red Spitzer/IRAC [3.6]-[4.5] color indicative of contamination by strong oxygen emission in the [4.5] band. With a total integration of $\sim$4.3 hours, our data reveal an emission line at $\simeq$11776 {\AA} which we argue is likely Ly$\alpha$ at a redshift $z_{spec}=8.683^{+0.001}_{-0.004}$, in good agreement with the photometric estimate. The line was detected independently on two nights using different slit orientations and its detection significance is $\sim7.5\sigma$. An overlapping skyline contributes significantly to the uncertainty on the total line flux although the significance of the detected line is robust to a variety of skyline-masking procedures. By direct addition and a Gaussian fit, we estimate a 95\% confidence range of 1.0--2.5$\times10^{-17}$ erg s$^{-1}$ cm$^{-2}$, corresponding to a rest-frame equivalent width of 17--42 {\AA}. EGSY8p7 is the most distant galaxy confirmed spectroscopically to date, and the third luminous source in the EGS field beyond $z_{phot}\gtrsim7.5$ with detectable Ly$\alpha$ emission viewed at a time when the intergalactic medium is believed to be fairly neutral. Although the reionization process was probably patchy, we discuss whether luminous sources with prominent IRAC color excesses may harbor harder ionizing spectra than the dominant fainter population thereby creating earlier ionized bubbles. Further spectroscopic follow-up of such bright sources promises important insight into the early formation of galaxies.Comment: V3: ApJL accepted; 7 pages, 4 figures, 1 tabl

Phases in the MSSM, Electric Dipole Moments and Cosmological Dark Matter

We consider the effect of CP violating phases in the MSSM on the relic density of the lightest supersymmetric particle (LSP). In particular, we find that the upper limits on the LSP mass are relaxed when phases in the MSSM are allowed to take non-zero values when the LSP is predominantly a gaugino (bino). Previous limits of \mb \la 250 GeV for $\Omega h^2 < 0.25$ can be relaxed to \mb \la 650 GeV. We also consider the additional constraints imposed by the neutron and electron electric dipole moments induced by these phases. Though there is some restriction on the phases, the bino mass may still be as large as $\sim$ 350 GeV and certain phases can be arbitrarily large.Comment: 10 pages in LaTeX, with 4 Postscript figures (included

A spectroscopic search for AGN activity in the reionization era

The ubiquity of Lyman alpha (Ly$\alpha$) emission in a sample of four bright [O III]-strong star-forming galaxies with redshifts above 7 has led to the suggestion that such luminous sources represent a distinct population compared to their fainter, more numerous, counterparts. The presence of Ly$\alpha$ emission within the reionization era could indicate that these sources created early ionized bubbles due to their unusually strong radiation, possibly due to the presence of active galactic nuclei. To test this hypothesis we have secured long integration spectra with XSHOOTER on the VLT for three $z\simeq$7 sources selected to have similar luminosities and prominent excess fluxes in the IRAC 3.6 or 4.5$\mu$m band, usually attributed to strong [O III] emission. We secured additional spectroscopy for one of these galaxies at $z$=7.15 using MOSFIRE at the Keck telescope. For this, the most well-studied source in our sample with the strongest IRAC excess, we detect prominent nebular emission from He II and NV indicative of a non-thermal source. For the other two sources at $z$=6.81 and $z$=6.85, for which no previous optical/near infrared spectroscopy was initially available, Ly$\alpha$ is seen in one and CIII] emission in the other. Although a modest sample, our results further support the hypothesis that the phenomenon of intense [O III] emission is associated preferentially with sources lying in early ionized bubbles. However, even though one of our sources at $z$=7.15 clearly indicates the presence of non-thermal radiation, such ionized bubbles may not uniquely arise in this manner. We discuss the unique advantages of extending such challenging diagnostic studies with JWST.Comment: 11 pages, 7 figures, submitted to Ap

Water intoxication presenting as maternal and neonatal seizures: a case report.

Introduction We present an unusual case of fitting in the mother and newborn child, and the challenges faced in the management of their hyponatraemia due to water intoxication. Case presentation A previously well 37-year-old, primigravid Caucasian woman presented with features mimicking eclampsia during labour. These included confusion, reduced consciousness and seizures but without a significant history of hypertension, proteinuria or other features of pre-eclampsia. Her serum sodium was noted to be low at 111 mmol/litre as was that of her newborn baby. She needed anti-convulsants with subsequent intubation to stop the fitting and was commenced on a hypertonic saline infusion with frequent monitoring of serum sodium. There is a risk of long-term neurological damage from central pontine myelinolysis if the hyponatraemia is corrected too rapidly. Mother and baby went on to make a full recovery without any long-term neurological complications. Conclusion There is little consensus on the treatment of life-threatening hyponatraemia. Previous articles have outlined several possible management strategies as well as their risks. After literature review, an increase in serum sodium concentration of no more than 8–10 mmol/litre in 24 hours is felt to be safe but can be exceeded with extreme caution if life-threatening symptoms do not resolve. Formulae exist to calculate the amount of sodium needed and how much hypertonic intravenous fluid will be required to allow safer correction. We hypothesise the possible causes of hyponatraemia in this patient and underline its similarity in symptom presentation to eclampsia