Heavy metal contamination of soil in mechanic workshops

The distribution of metal in soil from mechanic workshops around Zaria, Nigeria (Latitude: 11° 4' 0 N, Longitude: 7° 42' 0 E) was studied. The types of mechanic workshops considered were motorcycle, motorcar, truck/lorries and generator set. The soils were sampled in August 2010. The results indicated that there was an increase in the metal content of soil in all types of mechanic workshops. The heavy metal (nickel, copper, zinc, lead and arsenic) content of the soil was compared with recommended limits. The percentage composition of some of the heavy metals, in many of the samples, were found to be in excess of the considered set limit, particularly for lead for which the percentage of soil samples analyzed from motorcycle, motorcar, truck/lories and generator set mechanic workshops in excess of the considered recommended set limit was found to be 88.89, 100, 100 and 100% respectively. 11.1% of all the samples analyzed were found to contain arsenic in excess of recommended limit. Statistical analysis of the heavy metal content (one-way analysis of variance) indicated that the Zn and Pb contents of soil from mechanic workshops were not functions of the workshop type (P > 0.05) but the nickel and copper contents were found to be dependent on workshop type (P < 0.05).Keywords: Elemental analysis, Heavy metals, Mechanic workshop, Soil, Zari

Anomaly and a QCD-like phase diagram with massive bosonic baryons

We study a strongly coupled $Z_2$ lattice gauge theory with two flavors of quarks, invariant under an exact $\mathrm{SU}(2)\times \mathrm{SU}(2) \times \mathrm{U}_A(1) \times \mathrm{U}_B(1)$ symmetry which is the same as QCD with two flavors of quarks without an anomaly. The model also contains a coupling that can be used to break the $\mathrm{U}_A(1)$ symmetry and thus mimic the QCD anomaly. At low temperatures $T$ and small baryon chemical potential $\mu_B$ the model contains massless pions and massive bosonic baryons similar to QCD with an even number of colors. In this work we study the $T-\mu_B$ phase diagram of the model and show that it contains three phases : (1) A chirally broken phase at low $T$ and $\mu_B$, (2) a chirally symmetric baryon superfluid phase at low $T$ and high $\mu_B$, and (3) a symmetric phase at high $T$. We find that the nature of the finite temperature chiral phase transition and in particular the location of the tricritical point that seperates the first order line from the second order line is affected significantly by the anomaly.Comment: 22 pages, 16 figures, 5 tables, references adde

Crystal Structures of the structure-selective nuclease Mus81-Eme1 bound to flap DNA substrates

The Mus81-Eme1 complex is a structure-selective endonuclease with a critical role in the resolution of recombination intermediates during DNA repair after interstrand cross-links, replication fork collapse, or double-strand breaks. To explain the molecular basis of 3 ' flap substrate recognition and cleavage mechanism by Mus81-Eme1, we determined crystal structures of human Mus81-Eme1 bound to various flap DNA substrates. Mus81-Eme1 undergoes gross substrate-induced conformational changes that reveal two key features: (i) a hydrophobic wedge of Mus81 that separates pre- and post-nick duplex DNA and (ii) a 5 ' end binding pocket that hosts the 5 ' nicked end of post-nick DNA. These features are crucial for comprehensive protein-DNA interaction, sharp bending of the 3 ' flap DNA substrate, and incision strand placement at the active site. While Mus81-Eme1 unexpectedly shares several common features with members of the 5 ' flap nuclease family, the combined structural, biochemical, and biophysical analyses explain why Mus81-Eme1 preferentially cleaves 3 ' flap DNA substrates with 5 ' nicked ends.X11119Ysciescopu

The College of Medicine in the Republic of Malawi: towards sustainable staff development

BACKGROUND: Malawi has a critical human resources problem particularly in the health sector. There is a severe shortage of doctors; there are only few medical specialists. The College of Medicine (COM) is the only medical school and was founded in 1991. For senior staff it heavily depends on expatriates. In 2004 the COM started its own postgraduate training programme (Master of Medicine) in the clinical specialties. METHODS: We explore to what extent a brain drain took place among the COM graduates by investigating their professional development and geographical distribution. Using current experience with the postgraduate programme, we estimate at what point all senior academic positions in the clinical departments could be filled by Malawians. We demonstrate the need for expatriate staff for its most senior academic positions in the interim period and how this can be phased out. Lastly we reflect on measures that may influence the retention of Malawian doctors. RESULTS: Since the start of the COM 254 students have graduated with an average of 17 students per year. Most (60%) are working in Malawi. Of those working abroad, 60% are in various postgraduate training programmes. In 2015, adequate numbers of Malawi senior academics should be available to fill most senior positions in the clinical departments, taking into account a 65% increase in staff to cope with increasing numbers of students. CONCLUSION: There seems to be no significant brain drain among graduates of the COM. The postgraduate programme is in place to train graduates to become senior academic staff. In the interim, the COM depends heavily upon expatriate input for its most senior academic positions. This will be necessary at least until 2015 when sufficient numbers of well trained and experienced Malawian specialists may be expected to be available. Improved pay structure and career development perspectives will be essential to consolidate the trend that most doctors will remain in the country

On the Maxwell-Stefan approach to multicomponent diffusion

We consider the system of Maxwell-Stefan equations which describe multicomponent diffusive fluxes in non-dilute solutions or gas mixtures. We apply the Perron-Frobenius theorem to the irreducible and quasi-positive matrix which governs the flux-force relations and are able to show normal ellipticity of the associated multicomponent diffusion operator. This provides local-in-time wellposedness of the Maxwell-Stefan multicomponent diffusion system in the isobaric, isothermal case.Comment: Based on a talk given at the Conference on Nonlinear Parabolic Problems in Bedlewo, Mai 200

High coverage of mass drug administration for lymphatic filariasis in rural and non-rural settings in the Western Area, Sierra Leone

<p>Abstract</p> <p>Background</p> <p>Lymphatic filariasis elimination programs are based upon preventative chemotherapy annually in populations with prevalence more than or equal to 1%. The goal is to treat 80% of the eligible, at risk population yearly, for at least 5 years, in order to interrupt transmission and prevent children from becoming infected. This level of coverage has been a challenge in urban settings. Assessing the coverage in a rapidly growing urban/non-rural setting with inadequate population data is also problematic. In Sierra Leone, a 5-day preventative chemotherapy campaign was carried out in the Western Area including the capital: Freetown. An intensive, social mobilization strategy combined traditional and modern communication channels. To aid dissemination of appropriate information Frequently Asked Questions were developed and widely circulated. The population of the Western Area has grown faster than projected by the 2004 National Census due to the post-war settlement of internally displaced persons. As a reliable denominator was not available, independent monitoring was adapted and performed "in process" to aid program performance and "end process" to assess final coverage.</p> <p>Results</p> <p>In 5 days 1,104,407 eligible persons were treated. Using the projected population from the 2004 census this figure represented coverage of 116% in the Urban Western Area and 129% in the Rural Western Area. Independent monitors interviewed a total of 9,253 persons during the 2 End Process days representing 1% of the projected population. Of these, 85.8% recalled taking both ivermectin and albendazole (Urban: 85.2%, Rural: 87.1%). No serious adverse drug reactions were reported.</p> <p>Conclusion</p> <p>The paper presents the key elements of success of the social mobilization and implementation strategy and describes the independent monitoring used to estimate final coverage in this urban/non-rural setting where the current population size is uncertain. This implementation strategy and Independent Monitoring tool could be useful in similar, rapidly growing cities implementing lymphatic filariasis elimination programs.</p

QCD-like theories at nonzero temperature and density

We investigate the properties of hot and/or dense matter in QCD-like theories with quarks in a (pseudo)real representation of the gauge group using the Nambu-Jona-Lasinio model. The gauge dynamics is modeled using a simple lattice spin model with nearest-neighbor interactions. We first keep our discussion as general as possible, and only later focus on theories with adjoint quarks of two or three colors. Calculating the phase diagram in the plane of temperature and quark chemical potential, it is qualitatively confirmed that the critical temperature of the chiral phase transition is much higher than the deconfinement transition temperature. At a chemical potential equal to half of the diquark mass in the vacuum, a diquark Bose-Einstein condensation (BEC) phase transition occurs. In the two-color case, a Ginzburg-Landau expansion is used to study the tetracritical behavior around the intersection point of the deconfinement and BEC transition lines, which are both of second order. We obtain a compact expression for the expectation value of the Polyakov loop in an arbitrary representation of the gauge group (for any number of colors), which allows us to study Casimir scaling at both nonzero temperature and chemical potential.Comment: JHEP class, 31 pages, 7 eps figures; v2: error in Eq. (3.11) fixed, two references added; matches published versio

Dissolvable Template Nanoimprint Lithography: A Facile and Versatile Nanoscale Replication Technique

Nanoimprinting lithography (NIL) is a next-generation nanofabrication method, capable of replicating nanostructures from original master surfaces. Here, we develop highly scalable, simple, and nondestructive NIL using a dissolvable template. Termed dissolvable template nanoimprinting lithography (DT-NIL), our method utilizes an economic thermoplastic resin to fabricate nanoimprinting templates, which can be easily dissolved in simple organic solvents. We used the DT-NIL method to replicate cicada wings which have surface nanofeatures of ∼100 nm in height. The master, template, and replica surfaces showed a >∼94% similarity based on the measured diameter and height of the nanofeatures. The versatility of DT-NIL was also demonstrated with the replication of re-entrant, multiscale, and hierarchical features on fly wings, as well as hard silicon wafer-based artificial nanostructures. The DT-NIL method can be performed under ambient conditions with inexpensive materials and equipment. Our work opens the door to opportunities for economical and high-throughput nanofabrication processes

Redundancy in Genotyping Arrays

Despite their unprecedented density, current SNP genotyping arrays contain large amounts of redundancy, with up to 40 oligonucleotide features used to query each SNP. By using publicly available reference genotype data from the International HapMap, we show that 93.6% sensitivity at <5% false positive rate can be obtained with only four probes per SNP, compared with 98.3% with the full data set. Removal of this redundancy will allow for more comprehensive whole-genome association studies with increased SNP density and larger sample sizes

The sign problem across the QCD phase transition

The average phase factor of the QCD fermion determinant signals the strength of the QCD sign problem. We compute the average phase factor as a function of temperature and baryon chemical potential using a two-flavor NJL model. This allows us to study the strength of the sign problem at and above the chiral transition. It is discussed how the $U_A(1)$ anomaly affects the sign problem. Finally, we study the interplay between the sign problem and the endpoint of the chiral transition.Comment: 9 pages and 9 fig