Spherically Symmetric Gravitational Collapse

In this paper, we discuss gravitational collapse of spherically symmetric spacetimes. We derive a general formalism by taking two arbitrary spherically symmetric spacetimes with $g_{00}=1$. Israel's junction conditions are used to develop this formalism. The formulae for extrinsic curvature tensor are obtained. The general form of the surface energy-momentum tensor depending on extrinsic curvature tensor components is derived. This leads us to the surface energy density and the tangential pressure. The formalism is applied to two known spherically symmetric spacetimes. The results obtained show the regions for the collapse and expansion of the shell.Comment: 12 pages, 4 figures, accepted for publication in Mod. Phys. Lett.

Design and Implementation of S-MARKS: A Secure Middleware for Pervasive Computing Applications

As portable devices have become a part of our everyday life, more people are unknowingly participating in a pervasive computing environment. People engage with not a single device for a specific purpose but many devices interacting with each other in the course of ordinary activity. With such prevalence of pervasive technology, the interaction between portable devices needs to be continuous and imperceptible to device users. Pervasive computing requires a small, scalable and robust network which relies heavily on the middleware to resolve communication and security issues. In this paper, we present the design and implementation of S-MARKS which incorporates device validation, resource discovery and a privacy module

Paracrine orchestration of intestinal regeneration and aging

Cellular plasticity is integral for restoring tissue homeostasis following damages. Studies on the intra-epithelial mechanisms of tissue regeneration were greatly facilitated by the in vitro culture of mouse and human 3-dimensional intestinal organoids. However, organoids are typically grown in a reductionistic approach in the reconstituted hydrogel matrices that do not recapitulate the complexity of the native environment. Moreover, epithelial repair in vivo involves many extracellular matrix components and inputs from the mesenchyme. In this dissertation work, epithelial regeneration is modeled by re-epithelializing decellularized small intestinal matrix (iECM) ex vivo. iECM is a bare extracellular matrix of the small intestine with distinct crypt and villi structures resembling native small intestinal architecture. Interestingly, epithelial cells seeded on iECM displayed Tgfbeta pathway-dependent activation of the fetal-like state, a pro-regenerative program necessary for tissue regeneration in vivo – suggesting that the epithelial growth on iECM recapitulates the early epithelial response during tissue regeneration. Furthermore, we identify Asporin (Aspn), an ECM-bound proteoglycan, as a critical mediator of such injury-induced cellular reprogramming. Aspn is produced by the mesenchyme, and we show that its effect on epithelial Tgfbeta-signaling via CD44 is critical for fetal-like conversion. Furthermore, we demonstrate that Aspn is transiently increased upon chemotherapy-induced damage and is pivotal for a timely induction of the fetal-like state and tissue regeneration. In contrast to young, persistently high level of Aspn in the old intestine stagnates damaged epithelium in the fetal-like state, thereby compromising tissue repair. In addition, the aged ECM microenvironment reduces the regenerative capacity of young intestinal epithelium by suppressing intestinal stem cells (ISCs) ex vivo– underscoring the role of the ECM microenvironment in epithelial aging. In summary, we establish a simple platform for modeling epithelial injury responses ex vivo and show that the mesenchymal Aspn-producing niche controls tissue repair by regulating epithelial fetal-like reprogramming. Jointly, this dissertation work unfolds the dynamic nature and paracrine regulation of intestinal stem cells by their niche during homeostasis, regeneration, and aging. These findings may enable designing therapeutics for promoting intestinal regeneration and repair in chemotherapy recipient old humans.Solujen muovautuvuus on tärkeä tekijä kudosten korjaantuessa vaurioilta. Epiteelisisäisten kudosuusiutumismekanismien tutkimukset ovat hyötyneet valtavasti kolmiulotteista hiiri- ja ihmis suoliorganoidi kudosviljelymenetelmistä. Organoidit kasvatetaan kuitenkin yksinkertaistetusti uudelleen muodostetuissa hydrogeelimatriiseissa, jotka eivät täysin vastaa alkuperäisen kudoksen monimuotoisuutta. Lisäksi epiteelikudoksen korjaantuminen in vivo riippuu myös monista soluväliaineen komponenteista sekä muiden solutyyppien, kuten mesenkyymisolujen, signaaleista. Tässä väitöskirjassa epiteelin korjaantuminen mallinnetaan kasvattamalla uudelleen epiteelikudosta ohutsuolen soluväliainematriisillä, josta on ensin poistettu solut (iECM). Paljaassa iECM:ssä ohutsuolen soluväliaineen krypta- ja villusrakenteet ovat säilyneet, muistuttaen alkuperäistä kudosta. iECM:llä kasvatetut epiteelisolut omaksuvat nopeasti transforming growth factor-beta (Tgfbeta) reitti riippuvaisen sikiöaikaisen kudosuusiutumisohjelman, joka on välttämätön epiteelin uusiutumiselle in vivo. Epiteelin kasvattaminen iECM:llä mallintaa näin ollen epiteelin ensivasteen kudosuusiutumisen aikana. Lisäksi Asporin-niminen (Aspn) soluväliaineen sitoutunut proteiiniglykaani tunnistetaan tällaisen vaurion aikaansaaman solujen uudelleenohjauksen tärkeäksi välittäjäksi. Aspn tuotetaan mesenkyymissä, ja tässä näytetään, että Aspn:n vaikutukset Tgfbeta-signalointiin kantasoluissa ja niiden jälkeläisissä sijaitsevan CD44:n kautta on kriittinen solujen muuttuessa sikiökaltaiseen tilaan. Lisäksi näytetään, että Aspn lisääntyy väliaikaisesti kemoterapian aikaansaamisessa vauriossa ja, että tämä on ratkaisevaa sikiöaikaisen tilan käynnistyksen ajoituksen ja kudoksen korjaantumisen kannalta. Vanhassa suolessa, toisin kuin nuoressa, jatkuvasti korkealla tasolla oleva Aspn pysäyttää vaurioituneen epiteelin sikiökaltaiseen tilaan, mikä heikentää kudoksen korjaantumista. Vanhentunut soluväliaine myös vähentää nuoren epiteelin uusiutumiskykyä ex vivo rajoittamalla suolen kantasolujen toimintaa, mikä korostaa soluväliaineympäristön merkityksen epiteelin vanhenemisessa. Yhteenvedoksi, tässä väitöskirjassa perustetaan yksinkertainen menetelmä epiteelivaurioiden mallintamiseen ex vivo ja näytetään, että mesenkymaalinen Aspn-tuottava ympäristö ohjaa kudoksen korjaantumista säätelemällä epiteelin sikiönkaltaista uudelleenohjaantumista. Yhdessä, tämän väitöskirjan osatyöt osoittavat soluväliaineympäristön parakriinisen ja dynaamisen signaloinnin merkityksen suolen kantasolujen toimintaan homeostasiassa, kudoksen uusiutumisessa ja ikääntymisessä. Näiden löydösten pohjalta on mahdollista kehittää menetelmiä, jotka edesauttavat ikääntyneiden ihmisten kudosten uusiutumista ja korjaantumista kemoterapian aikana

Variability in lipid profile before and after coronary artery bypass grafting (CABG)

Objective: To investigate changes in total cholesterol, low density lipoprotein (LDL) cholesterol, high density lipoprotein (HDL) cholesterol, and triglycerides in serum of Pakistani patients before, immediately after and 5 days post CABG.Method: Serum samples from 31 consecutive Pakistani angina patients undergoing CABG at the Aga Khan University Hospital were analyzed for total cholesterol, LDL cholesterol, HDL cholesterol and triglycerides using kit methods.Results: Immediately after CABG, there is a significant decline in the mean levels of serum cholesterol, LDL cholesterol, HDL cholesterol and triglycerides. However, 5 days post CABG, there is a significant increase in the concentrations of total cholesterol (P = 0.01) and LDL cholesterol (P = 0.001) in nondiabetic angina patients (n = 13). Among the diabetic group of patients (n = 18), the levels of total cholesterol, LDL cholesterol, HDL cholesterol and triglycerides went back to the pre-operative levels within 5 days post CABG. Compared to European patients, Pakistani patients tend to have very low levels of HDL cholesterol (24.9 +/- 7.1 mg/dl) and high levels of triglycerides (185 +/- 50 mg/dl) on day 5 post CABG.Conclusion: Since risk of mortality following CABG increases with low level of HDL cholesterol and high level of triglycerides, close monitoring and treatment of high lipid levels of Pakistani patients following CABG is necessary to prevent further coronary events

Public Policy Barricading the Foreign Arbitral Award: A Comparative Analysis between UK, USA & France

The concept of public policy in International Arbitration is still extremely contentious, controversial, and complicated in modern times. Although legislation related to arbitration and practise have attempted to harmonise public policy so that parties may benefit from a globally recognised idea, judicial courts have made this effort almost difficult by giving a very loose & broad definition in the name of public policy. Moreover, the New York Convention gives little direction to national courts on how to interpret the public policy claim. In the name of local contract laws and fundamental principles of a nation, judge keeps hampering the enforcement of foreign award. Internal Law Association attempted to resolve this contention but couldn't come up with a definite definition which limits the policy in a closed structure. Despite the ambiguity of the issue, national courts in most developed arbitral countries interpret public policy narrowly. Because industrialised countries' courts typically see arbitral awards as a separate aspect of public policy; they are pro-enforcement. In this article we will comprehensively elaborate this attitude, legislation and case law study of developed nations like USA, UK and France

2-(4-Acetamido­benzene­sulfonamido)-3-methyl­butanoic acid

In the title compound, C13H18N2O5S, the benzene ring and the acetamide group are almost coplanar [dihedral angle = 5.6 (3)°], and the amine group projects almost vertically from this plane [C—C—S—N = −84.5 (7)°]. A short intra­molecular C—H⋯O contact occurs. In the crystal, O—H⋯O, N—H⋯O and N—H⋯(O,O) hydrogen bonds lead to a three-dimensional network. One of the methyl groups of the isopropyl residue is disordered over two orientations in a 0.747 (16):0.253 (16) ratio

Validation of bioelectrical impedance analysis for assessing dry weight of dialysis patients in Pakistan

Accurate dry weight estimation (DW) to achieve euvolemia is one of the key objectives of hemodialysis (HD). While conventionally DW is estimated by clinical examination, bioelectrical impedance analysis (BIA) has been proposed as an objective method to determine DW and has been tested extensively in the Western population. We aim to validate BIA for determining DW in a Pakistani population against the conventional clinician\u27s method. This is a single-center validation study conducted at two outpatient HD units of Aga Khan Hospital, Karachi. One hundred and forty-eight DW readings of patients who were on maintenance HD were taken both by BIA technology and by clinical assessment. The clinician was blinded to readings obtained by BIA. Data analysis was carried out using the Statistical Package for Social Sciences (SPSS) version 19. Median age of patients was 63 years (range 12-89). Nearly 54.1% of the samples were female (n = 80). Spearman\u27s correlation between the clinician\u27s estimate and BIA-derived DW showed a correlation coefficient of 0.982, which was statistically significant (

WEB BASED ENGINEERING EDUCATION

The use of Internet for distance education has received increasing attention over the past few years. But the real challenge of adapting this technology for engineering education is to facilitate the laboratory experiments via Internet. This paper discusses the software and hardware requirements of virtual courses/laboratories to provide interactive environment for designing and conducting classes/experiments. The examples provided demonstrate a virtual laboratory for Electrical Engineering courses and shows how similar laboratories can be implemented for other courses like Chemical Engineering, Mechanical Engineering and System Engineering etc. In a traditional university environment, virtual labs can also improve the Engineering curricula in a cost effective way by establishing a timely connection between theory and practice. The obstacles in introducing engineering education via digital media are also discussed