Chiral Perturbation Theory and Finite Size Effects on the Nucleon Mass in unquenched QCD

We calculate finite size effects on nucleon masses in chiral perturbation theory. We confront the theoretical predictions with N_f=2 lattice results and discuss chiral extrapolation formulae.Comment: talk at Lattice 03 (spectrum), 3 pages latex, 3 figures. Assignment of 2 data points to incorrect data sets in plot 1 and of 1 data point in plot 2 corrected. 1 fm lattice result updated. Conclusions unchange

The Nambu-Jona-Lasinio model with staggered fermions

We investigate the neighbourhood of the chiral phase transition in a lattice Nambu--Jona-Lasinio model, using both Monte Carlo methods and lattice Schwinger-Dyson equations.Comment: Talks at LAT93, Dallas, U.S.A. Postscript file, 6 pages, figures include

Decays of mesons with charm quarks on the lattice

We investigate mesons containing charm quarks on fine lattices with a^{-1} \sim 5 GeV. The quenched approximation is employed using the Wilson gauge action at \beta = 6.6 and nonperturbatively O(a) improved Wilson quarks. We present results for decay constants using various interpolating fields and give preliminary results for form factors of semileptonic decays of D_s mesons to light pseudoscalar mesons.Comment: 7 pages, 3 figures, talk presented at the XXV International Symposium on Lattice Field Theory, 30 July - 4 August 2007, Regensburg, German

MULTI-HAZARD RISK ASSESSMENT OF QURUMBAR VALLEY, GHIZER, GILGIT BALTISTAN, PAKISTAN

Being located in a seismically active zone, these mountain valleys are exposed to different hydro-meteorological hazards like rockfall, debris flow, landslide, ice avalanches, and glacial lake outburst flood (GLOFs).  The present study is to investigate different multi-hazards and their prevailing risk in the particular area of Qurumbar valley Ishkoman. In the mid-nineteen and twenty centuries at least six devastating glacial lake outburst floods (GLOFs) has been recorded, initially, only the Qurumbar glacier was considered as the main cause of this outburst flood, later field investigation and interview from local inhabitant revealed that nine more tributary glacier are existing in the area. The recent outburst of flood in the Badswat area of Qurumbar Ishkoman is also considerable, submerging 12 houses and a stretch of roads. Apart from it, the physical vulnerability of the area is increasing, as new areas are being used for housing with the increase in population. The study area is exposed to several other natural hazards like rock fall, debris flows, ice avalanches, and bank erosion. The present study is based on quantitative and qualitative approaches in assistance with GIS/RS an emergent application. The following methodologies were adapted to gather the primary and secondary data for GIS/RS processing. The primary data comprises GIS data and procurement and development and field data. The field data contain ground-truthing /validation. The community-based Hazard Vulnerability Risk Assessment (HVRA) was also carried out to know about human perception. Secondary data has been collected from different literature. Both the data were put into GIS for the processing which gives us our final developmental tools in the form of maps. The hazard and risk map of the Qurumbar Ishkoman depict that flash floods, debris flow, bank erosion, and GLOFs account for major hazards in Qurumbar valley. It is concluded based on our outcomes i.e., hazard and risk maps that earthquake is the main hazard of the area while flash floods, GLOFs, debris flow, bank erosion and the bank collapsed are the main hazards of the area. It is very important to systematically integrate map information into the planning and management process which contributes to a safer environment

Determination of Light and Strange Quark Masses from Full Lattice QCD

We compute the light and strange quark masses m_l = (m_u+m_d)/2 and m_s, respectively, in full lattice QCD with N_f=2 flavors of light dynamical quarks. The renormalization constants, which convert bare quark masses into renormalized quark masses, are computed nonperturbatively, including the effect of quark-line disconnected diagrams. We obtain m_l=4.7(2)(3) MeV and m_s=119(5)(8) MeV in the MSbar scheme at the scale 2 GeV.Comment: 7 pages, 8 figure

Chiral Extrapolations and the Covariant Small Scale Expansion

We calculate the nucleon and the delta mass to fourth order in a covariant formulation of the small scale expansion. We analyze lattice data from the MILC collaboration and demonstrate that the available lattice data combined with our knowledge of the physical values for the nucleon and delta masses lead to consistent chiral extrapolation functions for both observables up to fairly large pion masses. This holds in particular for very recent data on the delta mass from the QCDSF collaboration. The resulting pion-nucleon sigma term is sigma_{piN} = 48.9 MeV. This first quantitative analysis of the quark-mass dependence of the structure of the Delta(1232) in full QCD within chiral effective field theory suggests that (the real part of) the nucleon-delta mass-splitting in the chiral limit, Delta_0 = 0.33 GeV, is slightly larger than at the physical point. Further analysis of simultaneous fits to nucleon and delta lattice data are needed for a precision determination of the properties of the first excited state of the nucleon.Comment: 11 pp, 2 figs, version accepted for publication in Phys. Lett.

Chiral perturbation theory with Wilson-type fermions including a2a^2 effects: Nf=2N_f=2 degenerate case

We have derived the quark mass dependence of $m_{\pi}^2$, $m_{\rm AWI}$ and $f_{\pi}$, using the chiral perturbation theory which includes the $a^2$ effect associated with the explicit chiral symmetry breaking of the Wilson-type fermions, in the case of the $N_f=2$ degenerate quarks. Distinct features of the results are (1) the additive renormalization for the mass parameter $m_q$ in the Lagrangian, (2) $O(a)$ corrections to the chiral log ($m_q\log m_q$) term, (3) the existence of more singular term, $\log m_q$, generated by $a^2$ contributions, and (4) the existence of both $m_q\log m_q$ and $\log m_q$ terms in the quark mass from the axial Ward-Takahashi identity, $m_{\rm AWI}$. By fitting the mass dependence of $m_\pi^2$ and $m_{\rm AWI}$, obtained by the CP-PACS collaboration for $N_f=2$ full QCD simulations, we have found that the data are consistently described by the derived formulae. Resumming the most singular terms $\log m_q$, we have also derived the modified formulae, which show a better control over the next-to-leading order correction.Comment: 21 pages, 4 figures (10 eps files), Revtex4, some discussions and references added, the final version to appear in PR

Bidirectional cavopulmonary shunt for cyanotic heart disease: surgical experience from a developing country

Objective: The importance of bidirectional cavopulmonary anastomosis for palliation of complex cyanotic con-genital heart disease is widely recognized. This study was conducted to highlight our surgical experience withthis procedure in a developing country.Methods: A retrospective study was conducted using medical records at the Aga Khan University Hospital,Karachi, Pakistan. Clinical findings at presentation, anatomical defects seen on transthoracic echocardiography,pre-operative McGoon index, cardiopulmonary bypass time, use of cardioplegia,post-procedure oxygen satura-tions and complications were evaluated. Results: A total of 8 patients underwent bidirectional cavopulmonary anastomosis. There were 6 males (75%)and 2 females (25%). Ages and weights atoperation averaged 5.7 ± 3.7 years (range 2-14 years) and 18.6 ±10.4 kg (range 8.5-35.5 kg) respectively. The most common symptoms were the presence of cyanosis in all(100%) patients followed by recurrent respiratory tract infections in 3 (37.5%) patients. Transthoracic echocar-diography revealed 6 (75%) patients with atrial septal defects, 5 (62.5%) with tricuspid atresia, 3 (37.5%) with ventricular septal defects, 3 (37.5%) with malposition of great vessels, 2 (25%) with pulmonary stenosis and 2(25%) with double inlet left ventricles. The mean pre-procedure McGoon index was 2.1 ± 0.5 (range 1.37-2.80).All patients received cardioplegia. Cardiopulmonary bypass was used in all patients for a mean time of 154.1 ± 83.6 minutes (range 60-298 minutes). All patients were ventilated for a mean period of 1.5 ± 0.7 days (range 1-3 days). The ICU stay was 3.0 ± 0.6 days (range 2-5 days) with a total hospital stay of 9.8 ± 3.8 days (range 7-18 days). The mean post-procedure oxygen saturation was 82.6 ± 3.5% (range 76-86%). The most commonpost-operative complication was supraventricular arrhythmia in 2 (25.0%) patients. There were no intra-opera- tive or early (within 7 days of procedure) deaths. One patient developed pulmonary artery hypertension and died 23 months later due to cardiac arrest. Conclusion: Patients tolerated the procedure well. After a mean follow-up of 10 months, 6 patients were assessed to be in New York Heart Association (NYHA) functional class I and one patient in NYHA class II.Clinical and post-procedural data gathered from our experience confirms the safety of bidirectional cavopul-monary anastomosi

AN OVERALL VIEW ON GEMSTONE MINING IN GILGIT-BALTISTAN: PROBLEMS AND MITIGATIONS

Gilgit-Baltistan has tremendous amount of gemstone wealth and thousands of miners are busy to explore this wealth, but due to unscientific and crude mining methods this mineral wealth goes into waste in many ways, like fractures, damages and total destructions of gemstone due to ill blasting methods and lack of proper training. Gemstone mining is done in all districts of Gilgit-Baltistan. According to a careful survey in July 2007, 32 types of Gemstones (Precious and Semiprecious) are found in GB, out of total production of gemstones produced in Pakistan 95% come from GB. According to this survey there are more than 2000 mines which produce different variety of gemstones and numbers of miners involved in this mining industry directly or indirectly are more than 25000.  Due to these crude and unscientific mining methods, improper camps without hygienic facilities, lack of proper mining equipment, lack of basic health facilities and safety tools and lack of mining equipment repairing facilities at mining sites, number of problems are arising. These problems include damage to the fauna and flora in mining areas, damage to the eco system due to blasting and flow of people; mountains are becoming vulnerable due to improper mines development, glaciers melting due to use of thermal generators, spreading of human filth and waste like plastic and at last polluting of the water. This research is based on the mitigation of all these problems to some extent. The damage to the fauna and flora may be reduced by controlling spreading of human filth and waste, controlled blasting may be done by using modern blasting techniques, proper mines of international standard may be developed by enforcing the mining rules, use of thermal generators may be prohibited by developing small hydro projects at sites and at last pollution of water may be controlled by training people to adopt the cleanliness drives time to time and equipment repairing facilities at sites as well.  &nbsp