957 resultados para Ba bio
Resumo:
Single-species management objectives may not be consistent within mixed fisheries. They may lead species to unsafe situations, promote discarding of over-quota and/or misreporting of catches. We provide an algorithm for characterising bio-economic reference points for a mixed fishery as the steady-state solution of a dynamic optimal management problem. The optimisation problem takes into account: i) that species are fishing simultaneously in unselective fishing operations and ii)intertemporal discounting and fleet costs to relate reference points to discounted economic profits along optimal trajectories. We illustrate how the algorithm can be implemented by applying it to the European Northern Stock of Hake (Merluccius merluccius), where fleets also capture Northern megrim (Lepidorhombus whiffiagonis) and Northern anglerfish (Lophius piscatorius and Lophius budegassa). We find that optimal mixed management leads to a target reference point that is quite similar to the 2/3 of the Fmsy single-species (hake) target. Mixed management is superior to singlespecies management because it leads the fishery to higher discounted profits with higher long-term SSB for all species. We calculate that the losses due to the use of the Fmsy single-species (hake) target in this mixed fishery account for 11.4% of total discounted profits.
Resumo:
Molecular dynamics (MD) simulation is employed to study the bio-adhesion in F1 ATP molecular motor. Histidine-peptide is widely used as linkage in micro systems because of its strong binding strength to metals. This paper focuses on the adhesion between a synthetic peptide containing 6xHis-tag (Gly-Gly-Lys-Gly-Gly-Lys-Gly-Gly-His-His-His-His-His-His) and metal substrate, which is used to define the position of the F1 ATP molecular motor on the metal substrate. It is shown that the binding strength between histidine and nickel substrate is the strongest, while that of copper is smaller and that of gold substrate is the smallest. From the result of simulation, we find that the stability of adhesion between histidine and the metal substate result of the ringed structure in histidine.
Resumo:
La tesis se ha centrado en la síntesis y caracterización estructural de materiales tipo perovskita: SrLnMRuO6 (Ln=La,Pr,Nd; M=Zn,Co,Mg,Ni,Fe) y ALn2CuTi2O9 (A=Ca,Ba; Ln=La,Pr,Nd,Sm). El estudio de las estructuras de los materiales se ha realizado mediante el análisis de los patrones de difracción en polvo de rayos-X, sincrotrón y/o neutrones. En el refinamiento por el método de Rietveld de las estructuras se han sustituido las coordenadas atómicas (el método más común), por coordenadas colectivas: las amplitudes de los modos que describen la distorsión de la fase prototipo. Los resultados generales para la serie SrLnMRuO6 (Ln=La,Pr,Nd; M=Zn,Co,Mg,Ni) a temperatura ambiente se ha recogido en un diagrama en el que se han indicado las amplitudes de los modos que transforman de acuerdo a las irreps en función del factor de tolerancia, ya que todos ellos cristalizan en la misma fase monoclínica (P21/n); y a temperaturas altas se ha construido un diagrama de fase. Los materiales SrLnFeRuO6 ( Ln=La,Pr,Nd) y CaLn2CuTi2O9 cristalizan en la fase ortorrómbica Pbnm a temperatura ambiente; mientras que BaLn2CuTi2O9 tienen una estructura más simétrica, I4/mcm. A altas temperaturas se han identificado las transiciones de fase inducidas por el cambio de temperatura.A temperaturas bajas se han analizado las estructuras magnéticas de algunos de los compuestos mediante difracción de neutrones.
Resumo:
Nano-fibrillar arrays are fabricated using polystyrene materials. The average diameter of each fiber is about 300 nm. Experiments show that such a fibrillar surface possesses a relatively hydrophobic feature with a water contact angle of 142 degrees. Nanoscale friction properties are mainly focused on. It is found that the friction force of polystyrene nano-fibrillar surfaces is obviously enhanced in contrast to polystyrene smooth surfaces. The apparent coefficient of friction increases with the applied load, but is independent of the scanning speed. An interesting observation is that the friction force increases almost linearly with the real contact area, which abides by the fundamental Bowden-Tabor law of nano-scale friction.
Resumo:
Paziente paliatiboak, heriotzera hurbilduz doazen heinean, hainbat erabaki hartzera behartuta ikusten dute euren burua. Horrekin erlazionatuta, kalitatezko adierazle bezala, hiltzeko lekuaren aukeraketa aurkituko litzateke. Hau, urteekin eraldatuz joan da, aukera gehiago zabalduz gaixoari. Helburuak: paziente paliatiboak, Europa mailan, hiltzeko aukeratuko luketen lekuaren eta azkenean hil egiten diren lekuaren arteko bat etortze mailaren analisia. Horrez gain, kongruentziarik ematen ez den kasuetan, zeintzuk faktore esku hartzen duten aztertu da. Diseinua: bibliografiaren berrikuspena. Metodoak: bilaketa bibliografiko bat burutu da datu base ezberdinetan (Pubmed, IME, Cuiden). Barne hartze eta baztertze irizpideak erabili ondoren, 24 artikuluren analisia egin da. Emaitzak: gaixo paliatiboen artean, etxean hil nahi duten eta bertan hiltzen direnak %48a dira. Bestetik, ospitalean hiltzen direnen artetik soilik %30ak hil nahi du bertan. Beste aukera posibleak, erresidentzia eta ospitale paliatiboa izango lirateke, eta bertan hil nahi duten eta bertan hiltzea lortzen duten pazienteen ehunekoa %75 eta %26.5ekoa izango litzateke hurrenez-hurren.Ondorioak: paziente paliatiaboak hil nahi duen lekuaren eta errealitatean hil egiten den lekuaren artean bat etortze adierazgarririk ematen ez dela ikusi egin da. Nahia eta gertatutakoaren arteko ezadostasun maila, hainbat faktorerekin lotura dauka, batez ere, faktore biopsikosozialekin. Hala ere, estatuen artean desberdintasunak ematen dira, kongruentzia mailarik onena Erresuma Batuak lortzen duela ikustaraziz. Beraz, oraindik ere, programa eta politika ezberdinen sustapena beharrezkoa izango da, bizi bukaeran horrenbesteko pisua hartzen duen erabaki honetan.
Resumo:
Genero biolentziaren biktima diren emakume kasuak detektatu eta aurre egiteko osasun langileek daukaten garrantzia nabaria da. Helburua: argitaraturik dagoen bibliografiaren berrikuspen kritikoa eginez, erizainek eta bestelako osasun langileek genero biolentzian duten heziketa mailak kasuen detekzioan erlaziorik dagoen edo ez behatzea da. Metodologia: lehenik eta behin gaia finkatzeko asmoz bilaketa bibliografiko orokorra egin da. Ondoren, gai zehatzaren inguruko bibliografia bilaketa kritikoa egin da datu base desberdinetan. Lorturiko bibliografia guztitik aukeraketa egin eta azkenean hautatutakoekin gaia landu eta azkenik lanaren erredakzioa burutu da. Emaitzak eta diskusioa: Genero biolentzia kasuen detekzioa osasun profesionalek arlo horretan daukaten formazioarekin erlazionatzen da. Hala ere, orokorrean gehienek ez dute haien burua zera egiteko guztiz gai ikusten, beste batzuen artean formazio faltaren oztopoa sumatzeko dutelako. Ondorioak: genero biolentzian osasun profesionalek formazioa izatea ezinbestekoa da kasuen detekzio egokia burutzeko. Horrela, heziketa maila handituz, osasun profesionalek detekzioa egiteko gai izango dira, kasuen maneiu hobea lortuz.
Resumo:
Biological machines are active devices that are comprised of cells and other biological components. These functional devices are best suited for physiological environments that support cellular function and survival. Biological machines have the potential to revolutionize the engineering of biomedical devices intended for implantation, where the human body can provide the required physiological environment. For engineering such cell-based machines, bio-inspired design can serve as a guiding platform as it provides functionally proven designs that are attainable by living cells. In the present work, a systematic approach was used to tissue engineer one such machine by exclusively using biological building blocks and by employing a bio-inspired design. Valveless impedance pumps were constructed based on the working principles of the embryonic vertebrate heart and by using cells and tissue derived from rats. The function of these tissue-engineered muscular pumps was characterized by exploring their spatiotemporal and flow behavior in order to better understand the capabilities and limitations of cells when used as the engines of biological machines.
Resumo:
Lipid bilayer membranes are models for cell membranes--the structure that helps regulate cell function. Cell membranes are heterogeneous, and the coupling between composition and shape gives rise to complex behaviors that are important to regulation. This thesis seeks to systematically build and analyze complete models to understand the behavior of multi-component membranes.
We propose a model and use it to derive the equilibrium and stability conditions for a general class of closed multi-component biological membranes. Our analysis shows that the critical modes of these membranes have high frequencies, unlike single-component vesicles, and their stability depends on system size, unlike in systems undergoing spinodal decomposition in flat space. An important implication is that small perturbations may nucleate localized but very large deformations. We compare these results with experimental observations.
We also study open membranes to gain insight into long tubular membranes that arise for example in nerve cells. We derive a complete system of equations for open membranes by using the principle of virtual work. Our linear stability analysis predicts that the tubular membranes tend to have coiling shapes if the tension is small, cylindrical shapes if the tension is moderate, and beading shapes if the tension is large. This is consistent with experimental observations reported in the literature in nerve fibers. Further, we provide numerical solutions to the fully nonlinear equilibrium equations in some problems, and show that the observed mode shapes are consistent with those suggested by linear stability. Our work also proves that beadings of nerve fibers can appear purely as a mechanical response of the membrane.
Resumo:
We report on the conversion of near-ultraviolet radiation of 250-350 nm into near-infrared emission of 970-1100 nm in Yb3+-doped transparent glass ceramics containing Ba2TiSi2O8 nanocrystals due to the energy transfer from the silicon-oxygen-related defects to Yb3+ ions. Efficient Yb3+ emission (F-2(5/2)-> F-2(7/2)) was detected under the excitation of defects absorption at 314 nm. The occurrence of energy transfer is proven by both steady state and time-resolved emission spectra, respectively, at 15 K. The Yb2O3 concentration dependent energy transfer efficiency has also been evaluated, and the maximum value is 65% for 8 mol % Yb2O3 doped glass ceramic. These materials are promising for the enhancement of photovoltaic conversion efficiency of silicon solar cells via spectra modification.