Influence of Relative Position of the Tunnels: A Numerical Study on Twin Tunnels

The development of cities requires the use of underground area for the construction of transportation infrastructure facilities. Construction of twin tunnels or new tunnel close to the existing ones may be done horizontally, vertically or in inclined manner. In the case of horizontal tunnels the distribution of tunnel load will be more in lateral direction. Since cities are densely concentrated with tall structures, laterally distributed loads will induce settlement in the foundation of the structures. For a particular orientation of tunnels, the soil movement and internal forces in the lining will be affected by both the relative position of tunnels and the construction procedure. Hence the study on influence of these factors on the tunnel design gains importance. In the present study a numerical analysis has been carried out to evaluate the relative position of the twin tunnels in three directions in layered soil. The direction considered are horizontal alignment, vertical alignment and inclined alignment. Model twin tunnels have been constructed using numerical code Plaxis based on finite element analysis. Settlement analysis has been carried out for the different loading conditions on the tunnels in the selected directions. The results are presented in the form of surface settlement, bending moment and stresses in the lining of the tunnels for different orientation of tunnels. The construction of upper tunnel at first leads to both higher settlement and bending moment. The highest soil settlement is obtained for vertical aligned tunnels, while horizontal aligned tunnels cause the lowest settlement

Potential Genetic Polymorphisms Predicting Polycystic Ovary Syndrome (PCOS) in Sri Lankan Women: Comparison with Different Ethnicity

Polycystic ovary syndrome (PCOS) is the commonest endocrine disorder of young women with long-term metabolic risk and prevalence among pre-marital Sri Lankan women is 6.3%. Inheritance of PCOS is likely to be oilgogenic; the genetic basis remaining largely unknown in view of the complex pathophysiology. The genetics of expression of PCOS requires an in-depth study, particularly among Sri Lankan women who have a greater metabolic risk from an early age. The emergence of an unanimously accepted genetic marker for susceptible PCOS was affected based on inconsistent findings. In this review, we summarize the common genetic polymorphisms of PCOS from different countries and outline some genetic polymorphisms that are potentially associated with the risk of PCOS in Sri Lankan women. This information could uncover candidate genes associating with PCOS, which will be valuable for the development of novel diagnostic and treatment method

Mogućnost korišćenja mikroalgi u hrani za karnivorne vrste riba

Potreba za sastojcima visokog kvaliteta u proizvodnji hrane za ribe raste zajedno sa razvojem proizvodnje u akvakulturi u svetu. Riblje brašno i riblje ulje su najčešće birani sastojci za hranu za ribe zbog njihove visoke nutritivne vrednosti i ukusa. Riblje brašno sadrži onu količinu amino kiselina koja je ribi potrebna. Riblje ulje je odličan izvor esencijalnih n-3 masnih kiselina dugog lanca, koje su veoma važne za unapređenje zdravlja, kako kod riba tako i kod onih koji konzumiraju ribu. Riblje brašno i ulje su zamenjivani biljnim sastojcima u proteklih 25 godina. Međutim, biljn sastojci često sadrže širok spektar anti-nutririvnih sastojaka koji imaju negativan uticaj na zdravlje ribe kao i korišćenje hrane za ribe. Ulje biljnog porekla u hrani za ribe menja sastav masnih kiselina u tkivu ribe, umanjuje povoljan profil masnih kiselina pa dominiraju manje pogodne n-6 masne kiseline. Postoji sve veća zainteresovanost za pronalaženjem izvora hrane za ribe u nižim trofičkim nivoima morskih ekosistema, kao što su mikroalge. Morske mikroalge su primarni proizvođači n-3 masnih kiselina i zbog toga su verovatno bolja alternativa za riblje ulje od biljnog. Neke mikroalge imaju odgovarajući sastav proteina kao i profil amino kiselina. Cilj ovog eksperimenta je da istraži nutritivnu svarljivost (ADC) suve materije (DM), proteina i pepela mikroalgi Nanofrustulum (C3), Desmodesmus (C4) i Nannochloropsis (C1) koji su inkorporirani u hranu za Atlantskog lososa, Salmo salar. Dva testa svarljivosti su urađena sa Atlantskim lososom. Cilj prvog ekperimenta (inicijalni test, P, prosečna inicijalna težina ribe 1000g) bio je da istraži svarljivost sastojaka 3 alge tako što je kontrolna hrana bazirana na ribljem brašnu rastvorena sa 30% test sastojka (u odnosu 70:30). Ove tri vrste hrane su proizvedene hladnim procesom peletiranja. Drugi eksperiment (ekperiment provere, V; prosečna inicijalna težina ribe 436g), urađen je da bi potvrdio rezultate C1 i C4 korišćenjem ekstrudirane hrane. Feces je sakupljan metodom ceđenja. U oba eksperimenta, primećene su značajne razlike u svarljivosti ADC mikroalgi. Sveukupno, najviša ADC za proteine, DM i pepeo (P<0.05) utvrđena je kod hrane C3, dok nije bilo značajnih razlika između C1 i C4. Kada je reč o eksperimentu V, najviša ADC suve materije i proteina utvrđena je za hranu C1 (P<0.05), dok se razlika ADC pepela nije pokazala među različitim tipovima hrane. ADC proteina i suve materije je bio u istom opsegu kao i vrednosti eksperimenta P, dok je ADC pepela bio viši. Nutritivna svarljivost varira među različitim vrstama mikroalgi. Ona verovatno takođe zavisi od tehnoloških uslova procesuiranja hrane. Zasnovano na ADC vrednostima, iako je C3 pokazala bolji potencijal, njen visok sastav pepela i nizak sastav proteina, mogu biti ograničavajući factor za korišćenje ove mikroalge u ishrani za ribe. Velike razlike nisu pronađene u vrednostima svarljivosti između algi C1 i C4. Ova zapažanja treba dalje potvrditi dugoročnim eksperimentima hranjenja Atlantskog lososa da bi se u potpunosti definisao potencijal sva tri kandidata. Ova studija je deo projekta “Proizvodnja velikih dimenzija goriva i hrane iz mikroalgi”. Projekat je finansiran od strane Odeljenja za Energiju Sjedinjenih Američkih Država

Density matrix algorithm for the calculation of dynamical properties of low dimensional systems

I extend the scope of the density matrix renormalization group technique developed by White to the calculation of dynamical correlation functions. As an application and performance evaluation I calculate the spin dynamics of the 1D Heisenberg chain.Comment: 4 pages + 4 figures in one Latex + 4 postscript file

Wpływ rodzaju włókien na właściwości fizyczne laminatowych kompozytów polietylenu małej gęstości

In recent years, the increased interest in the design and fabrication of lightweight polymer composites with various combinations and stoichiometry is due to their enhancement of electrical, mechanical, thermal, and biological properties compared to the properties of conventional materials. With that view, the present study deals with the effects of low density polyethylene composites (LDPE) reinforced with epoxy resin, glass fiber, carbon fiber, and Kevlar towards the mechanical, thermal, and water absorption properties. The mechanical studies showed that the LDPE composite reinforced carbon fiber has the best tensile properties compared to other composites and this can be mostly due to the proper bonding and associated interaction between the polymeric matrix and the bidirectional layer of the fibers. Also, the carbon fiber reinforced composite has superior properties of impart energy compared to the other composites and the non-reinforced ones and this is attributed to the crystalline nature of carbon fiber. Further studies of the thermal properties indicated that the retention of thermal stability for all the fiber-reinforced polymer composites, while the water absorption revealed a considerable increase in the weight of Kevlar fiber-reinforced composite. From the overall analysis, the enhanced properties of LDPE matrix reinforced fibers are linked to the morphological changes that occurred and are directly affected by the nature of the fiber.Zwiększone w ostatnich latach zainteresowanie projektowaniem i wytwarzaniem lekkich kompozytów polimerowych wynika z ich lepszych właściwości elektrycznych, mechanicznych, termicznych i biologicznych w porównaniu z cechami materiałów konwencjonalnych. Zbadano wpływ rodzaju wzmocnienia (włókno szklane, włókno węglowe i włókno Kevlar) na właściwości mechaniczne, termiczne i absorpcję wody laminatowych kompozytów polietylenu małej gęstości (LDPE) z żywicą epoksydową. Stwierdzono, że kompozyt LDPE z włóknem węglowym, w porównaniu z innymi kompozytami, wykazuje najlepszą wytrzymałość na rozciąganie, co może wynikać głównie z interakcji polimerowej osnowy z dwukierunkową warstwą włókien. Ponadto kompozyt ten ma większą zdolność przenoszenia energii niż pozostałe badane kompozyty, co można przypisać krystalicznej budowie włókna węglowego. Badania właściwości termicznych wykazały stabilność termiczną wszystkich kompozytów polimerowych wzmocnionych włóknami oraz znaczną absorpcję wody kompozytu wzmocnionego włóknem Kevlar