Convergence of the mass-transport steepest descent scheme for the sub-critical Patlak-Keller-Segel model

Variational steepest descent approximation schemes for the modified Patlak-Keller-Segel equation with a logarithmic interaction kernel in any dimension are considered. We prove the convergence of the suitably interpolated in time implicit Euler scheme, defined in terms of the Euclidean Wasserstein distance, associated to this equation for sub-critical masses. As a consequence, we recover the recent result about the global in time existence of weak-solutions to the modified Patlak-Keller-Segel equation for the logarithmic interaction kernel in any dimension in the sub-critical case. Moreover, we show how this method performs numerically in one dimension. In this particular case, this numerical scheme corresponds to a standard implicit Euler method for the pseudo-inverse of the cumulative distribution function. We demonstrate its capabilities to reproduce easily without the need of mesh-refinement the blow-up of solutions for super-critical masses.

A relative double commutant theorem for hereditary sub-C*-algebras

We prove a double commutant theorem for hereditary subalgebras of a large class of C*-algebras, partially resolving a problem posed by Pedersen[8]. Double commutant theorems originated with von Neumann, whose seminal result evolved into an entire field now called von Neumann algebra theory. Voiculescu proved a C*-algebraic double commutant theorem for separable subalgebras of the Calkin algebra. We prove a similar result for hereditary subalgebras which holds for arbitrary corona C*-algebras. (It is not clear how generally Voiculescu's double commutant theorem holds.)

Transcatheter stent-valve implantation in a stenotic pulmonary conduit via a sub-xyphoidian access

Patients who develop a severe stenosis in biological pulmonary conduits previously implanted for pulmonary outflow trunk reconstructions are treated either by surgical re-replacement, or by transcatheter stent-valve implantation through a femoral vein access. A catheter-based sub-xyphoidian access through the right ventricle for stent-valve positioning in a pulmonary conduit has rarely been proposed. We describe the case of a 20-year-old man who underwent a pulmonary trunk reconstruction for a congenital pulmonary valve dysplasia and a few years later developed a stenosis in the pulmonary conduit. He was successfully treated with a 23 mm Edwards Sapien stent-valve implantation in pulmonary position, through an unusual right ventricular, sub-xyphoidian access and without contrast medium injections and pleura opening.

Public Governance, Health and Foreign Direct Investment in Sub-Saharan Africa

In this paper we diverge from the existing empirical literature on FDI determinants in two ways. First, we decompose the sources of the foreign direct investment (FDI) gap between Sub-Saharan Africa (SSA) and other developing regions. Once market size has been accounted for, we nd that SSA's FDI de cit is mostly explained by insufficient provision of public goods: low human capital accumulation, especially health, in SSA explains 100-140% of the inter-regional FDI gaps. Second, we estimate the indirect effect of infectious diseases on FDI through their direct impact on health. We find that a 1% point rise in HIV prevalence in the adult population is associated with a decrease in net FDI inflows of 3.5%, while a country in which 100% of the population is at risk of contracting deadly malaria receives about 16% less FDI than a similar country located in a malaria-free region.

Native-like, long synthetic peptides as components of sub-unit vaccines: practical and theoretical considerations for their use in humans.

Vaccines have been used as a successful tool in medicine by way of controlling many major diseases. In spite of this, vaccines today represent only a handful of all infectious diseases. Therefore, there is a pressing demand for improvements of existing vaccines with particular reference to higher efficacy and undisputed safety profiles. To this effect, as an alternative to available vaccine technologies, there has been a drive to develop vaccine candidate polypeptides by chemical synthesis. In our laboratory, we have recently developed a technology to manufacture long synthetic peptides of up to 130 residues, which are correctly folded and biologically active. This paper discusses the advantages of the molecularly defined, long synthetic peptide approach in the context of vaccine design, development and use in human vaccination.

La crisi sub-prime i el crack de 1929: Comparació d'episodis d'eufòria financera

Treball de recerca realitzat per un alumne d'ensenyament secundari i guardonat amb un Premi CIRIT per fomentar l'esperit científic del Jovent l'any 2009. La present investigació té per objecte d’estudi la relació, atès el període de turbulències econòmiques que travessa el món globalitzat, entre els episodis d’eufòria financera i les crisi financeres i econòmiques, i la periodicitat amb les que aquestes es produeixen. Aquesta pretén confrontar-se des d’una aproximació històric-econòmica, mitjançant l’anàlisi i la comparació de dos successos -el crack borsari de 1929 i la crisi sub-prime- per tal de demostrar la existència de comuns denominadors, i, a la llum dels resultats, apreciar les conclusions que aporta la Història. Serà, doncs, aquesta periodicitat i les seves implicacions la qual s'ambicionarà contrastar amb la realitat mitjançant l'aplicació i l'anàlisi pràctica de dos episodis rellevants i paradigmàtics, amb el recolzament i l'autoritat del model comparatiu establerts per l'economista John Kenneth Galbraith al seu llibre ''Breve historia de la euforia financiera''.

Suicidal expression among school-attending adolescents in a middle-income sub-Saharan country.

We investigated correlates for suicidal expression among adolescents in the Seychelles. Data on 1,432 students (52% females) were derived from the Global School-based Health Survey. Participants were divided into three groups: those with no suicidal behavior (N = 1,199); those with suicide ideation/SI (N = 89); and those reporting SI with a plan to carry out a suicide attempt/SISP (N = 139), each within a 12-month recall period. Using multinomial logistic regression, we examined the strength of associations with social, behavioral and economic indicators while adjusting for covariates. Sixteen percent of school-attending adolescents reported a suicidal expression (10% with a plan/6.2% without). Those reporting SI were younger (relative risk ratio RRR = 0.81; CI = 0.68-0.96), indicated signs of depression (RRR = 1.69; CI = 1.05-2.72) and loneliness (RRR=3.36; CI =1.93-5.84). Tobacco use (RRR = 2.34; CI = 1.32-4.12) and not having close friends (RRR = 3.32; CI = 1.54-7.15) were significantly associated with SI. Those with SISP were more likely to be female (RRR = 0.47; 0.30-0.74), anxious (RRR = 3.04; CI = 1.89-4.88) and lonely (RRR = 1.74; CI = 1.07-2.84). Having no close friends (RRR = 2.98; 1.56-5.69) and using tobacco (RRR = 2.41; 1.48-3.91) were also strongly associated. Having parents who were understanding was protective (RRR = 0.50; CI = 0.31-0.82). Our results suggest that school health promotion programs may benefit from targeting multiple factors associated with suicidal expression. More research, particularly multilevel designs are needed to identify peer and family influences which may modify associations with suicidality.

Sub-cortical and brainstem sites associated with chemo-stimulated increases in ventilation in humans.

We investigated the neural basis for spontaneous chemo-stimulated increases in ventilation in awake, healthy humans. Blood oxygen level dependent (BOLD) functional MRI was performed in nine healthy subjects using T2 weighted echo planar imaging. Brain volumes (52 transverse slices, cortex to high spinal cord) were acquired every 3.9 s. The 30 min paradigm consisted of six, 5-min cycles, each cycle comprising 45 s of hypoxic-isocapnia, 45 s of isooxic-hypercapnia and 45 s of hypoxic-hypercapnia, with 55 s of non-stimulatory hyperoxic-isocapnia (control) separating each stimulus period. Ventilation was significantly (p<0.001) increased during hypoxic-isocapnia, isooxic-hypercapnia and hypoxic-hypercapnia (17.0, 13.8, 24.9 L/min respectively) vs. control (8.4 L/min) and was associated with significant (p<0.05, corrected for multiple comparisons) signal increases within a bilateral network that included the basal ganglia, thalamus, red nucleus, cerebellum, parietal cortex, cingulate and superior mid pons. The neuroanatomical structures identified provide evidence for the spontaneous control of breathing to be mediated by higher brain centres, as well as respiratory nuclei in the brainstem.

Health Protection Sub-Group Report (PDF 32 KB)

PH Health Protection Sub-Group Interim Report January 2006

Re: Cost effectiveness of strategies to combat cardiovascular disease, diabetes, and tobacco use in sub-Saharan Africa and South East Asia: mathematical modelling study.

Rapid response to: Ortegón M, Lim S, Chisholm D, Mendis S. Cost effectiveness of strategies to combat cardiovascular disease, diabetes, and tobacco use in sub-Saharan Africa and South East Asia: mathematical modelling study. BMJ. 2012 Mar 2;344:e607. doi: 10.1136/bmj.e607. PMID: 22389337.

Effect of irrigation water and processing on the microbial quality of lettuces produced and sold on markets in Dakar (Senegal)

The aim of this survey is to assess the microbiological impact of irrigation water on lettuces produced on two urban agricultural sites and sold on markets; 6 and 7%, respectively, of lettuces coming from the sites of Pikine and Patte d'Oie were Salmonella spp. positive. Lettuces irrigated with shallow groundwater (''Ceanes'' water) were more contaminated (8% at both Pikine and Patte d'Oie sites) compared to those irrigated with wastewater (4% at Pikine) or well water (5% at Patte d'Oie). As for the lettuces in marketplaces, their contamination seems to depend on the type of treatment occurring before sale. Lettuces previously washed in the ``Ceanes'' were more contaminated than those rinsed with tap water at the marketplace. Salmonella spp. have been isolated from all marketplaces. However, the rates of contamination in markets surrounding Patte d'Oie are higher (9 and 11% at Grand Yoff and Dalifort) than those surrounding Pikine (4 and 2% at Zinc and Sham) or Rufisque, the control (2%). Our results confirm that the reuse of wastewater in irrigation is an alternative to animal manure. Its risk of microbial contamination can be significantly reduced by washing the vegetables with tap water before they are sold. Copyright (C) 2010 John Wiley & Sons, Ltd.

Confirmation of functional zones within the human subthalamic nucleus: patterns of connectivity and sub-parcellation using diffusion weighted imaging.

The subthalamic nucleus (STN) is a small, glutamatergic nucleus situated in the diencephalon. A critical component of normal motor function, it has become a key target for deep brain stimulation in the treatment of Parkinson's disease. Animal studies have demonstrated the existence of three functional sub-zones but these have never been shown conclusively in humans. In this work, a data driven method with diffusion weighted imaging demonstrated that three distinct clusters exist within the human STN based on brain connectivity profiles. The STN was successfully sub-parcellated into these regions, demonstrating good correspondence with that described in the animal literature. The local connectivity of each sub-region supported the hypothesis of bilateral limbic, associative and motor regions occupying the anterior, mid and posterior portions of the nucleus respectively. This study is the first to achieve in-vivo, non-invasive anatomical parcellation of the human STN into three anatomical zones within normal diagnostic scan times, which has important future implications for deep brain stimulation surgery.