991 resultados para Inherent chirality
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Electrical resistivity tomography (ERT) is a well-established method for geophysical characterization and has shown potential for monitoring geologic CO2 sequestration, due to its sensitivity to electrical resistivity contrasts generated by liquid/gas saturation variability. In contrast to deterministic inversion approaches, probabilistic inversion provides the full posterior probability density function of the saturation field and accounts for the uncertainties inherent in the petrophysical parameters relating the resistivity to saturation. In this study, the data are from benchtop ERT experiments conducted during gas injection into a quasi-2D brine-saturated sand chamber with a packing that mimics a simple anticlinal geological reservoir. The saturation fields are estimated by Markov chain Monte Carlo inversion of the measured data and compared to independent saturation measurements from light transmission through the chamber. Different model parameterizations are evaluated in terms of the recovered saturation and petrophysical parameter values. The saturation field is parameterized (1) in Cartesian coordinates, (2) by means of its discrete cosine transform coefficients, and (3) by fixed saturation values in structural elements whose shape and location is assumed known or represented by an arbitrary Gaussian Bell structure. Results show that the estimated saturation fields are in overall agreement with saturations measured by light transmission, but differ strongly in terms of parameter estimates, parameter uncertainties and computational intensity. Discretization in the frequency domain (as in the discrete cosine transform parameterization) provides more accurate models at a lower computational cost compared to spatially discretized (Cartesian) models. A priori knowledge about the expected geologic structures allows for non-discretized model descriptions with markedly reduced degrees of freedom. Constraining the solutions to the known injected gas volume improved estimates of saturation and parameter values of the petrophysical relationship. (C) 2014 Elsevier B.V. All rights reserved.
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Inhibitory receptors (iRs) are frequently associated with "T cell exhaustion". However, the expression of iRs is also dependent on T cell differentiation and activation. Therapeutic blockade of various iRs, also referred to as "checkpoint blockade", is showing -unprecedented results in the treatment of cancer patients. Consequently, the clinical potential in this field is broad, calling for increased research efforts and rapid refinements in the understanding of iR function. In this review, we provide an overview on the significance of iR expression for the interpretation of T cell functionality. We summarize how iRs have been strongly associated with "T cell exhaustion" and illustrate the parallel evidence on the importance of T cell differentiation and activation for the expression of iRs. The differentiation subsets of CD8 T cells (naïve, effector, and memory cells) show broad and inherent differences in iR expression, while activation leads to strong upregulation of iRs. Therefore, changes in iR expression during an immune response are often concomitant with T cell differentiation and activation. Sustained expression of iRs in chronic infection and in the tumor microenvironment likely reflects a specialized T cell differentiation. In these situations of prolonged antigen exposure and chronic inflammation, T cells are "downtuned" in order to limit tissue damage. Furthermore, we review the novel "checkpoint blockade" treatments and the potential of iRs as biomarkers. Finally, we provide recommendations for the immune monitoring of patients to interpret iR expression data combined with parameters of activation and differentiation of T cells.
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Flavonoidit ovat kasvien polyfenolisia sekundäärimetaboliitteja, jotka koostuvat 15-hiilisestä C6-C3-C6-perusrungosta. Niillä on havaittu useita terveyden kannalta edullisia ominaisuuksia kuten antioksidatiivisia, antikarsinogeenisia, antiallergeenisia, anti-inflammatorisia, estrogeenisia sekä antimikrobiaalisia vaikutuksia. Kasvimateriaalia käyttävän elintarviketeollisuuden sivuvirrat ovat flavonoidi-pitoisten jakeiden arvokkaita raaka-aineita. Tässä työssä tarkoituksena oli tutkia marjojen puristusjäännöksen sisältämien flavonoidien uuttamista ja uuttautumiseen vaikuttavia tekijöitä kuten liuottimen koostumusta ja määrää, uuttolämpötilaa ja -aikaa sekä liuottimen lisäaineita. Uutteet analysointiin HPLC:lla käyttäen ODS-2-kolonnia ja gradienttieluointia. Komponentit detektoitiin niille tyypillisillä UV-VIS-aallonpituuksilla ja identifioitiin vertaamalla flavonoidiprofiililtaan tunnettujen marjojen kromatogrammeihin. Antosyaanien kvantitatiiviseen analysointiin käytettiin spektrofotometrista pH-eromenetelmää ja tulokset ilmoitettiin syanidiini-3-glukosidina. Uutteiden kestävyyttä tutkittiin säilyttämällä näytteitä eri olosuhteissa sekä lisäämällä niihin uuton saantoon ja komponenttien säilyvyyteen vaikuttavia aineita. Useimmat tutkituista hapoista paransivat flavonoidien saantoa ja uutteiden säilyvyyttä, mutta esim. askorbiinihapon lisääminen nopeutti tiettyjen uutteen sisältämien flavonoidien tuhoutumista.
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Perinteisten markkinointiviestintäkanavien menettäessä jatkuvasti tehoaan mediakentän ja kohderyhmien sirpaloituessa yhä pienempiin yksiköihin markkinointiorganisaatiot etsivät vaihtoehtoisia tapoja tavoittaakseen kohdeyleisönsä. Yksi vaihtoehtoinen markkinointiviestintäkeino on tuotesijoittelu (product placement), jossa (merkki)tuotteita sijoitetaan erilaisten viihdetuotantojen, kuten elokuvien, televisio-ohjelmien ja tietokonepelien, tarinan yhteyteen, jotta yhä medialukutaitoisempi kohdeyleisö ei pystyisi välttämään kaupallista viestiä esimerkiksi vaihtamalla televisiokanavaa tai kääntämällä lehden sivua. Koska tuote on sijoitettu kerrottavan tarinan sisään, markkinointiviestin — eli tuotteen havaitsemisen — välttäminen on huomattavasti vaikeampaa kuin perinteisten markkinointiviestintämenetelmien kohdalla. Lisäksi, sijoitellut tuotteet ovat tavallisesti kiinteässä yhteydessä tarinan juonen ja henkilöhahmojen kanssa siten, että tuote saa näistä yhteyksistä positiivista vahvistusta imagolleen. Pro Gradu-tutkielman tarkoituksena oli selvittää tuotesijoittelun käyttökelpoisuutta markkinointiviestinnässä sekä miten kulutushyödykemarkkinoijat voivat hyödyntää menetelmää markkinointiviestintästrategioissaan. Tuotesijoittelun poikkeava luonne markkinointiviestintävälineenä tuotti kysymyksen miten tuotesijoittelua voitaisiin hyödyntää yhteistyössä muiden markkinointiviestintäkeinojen kanssa. Tätä varten tutkimuksessa tuotesijoittelu yhdistettiin integroidun markkinointiviestinnän (IMC) viitekehykseen. IMC-konsepti syntyi markkinointiviestinnässä vastaamaan samaan tarpeeseen kuin tuotesijoittelukin: pirstaloitunut mediakenttä ja yksittäiset kohderyhmät vaativat kehittyneempää ja yhtenäisempää markkinointiviestinnän suunnittelua ja toteutusta. Tutkimuksen johtopäätöksenä tuotesijoittelu todettiin käyttökelpoiseksi markkinointiviestintäkeinoksi mikäli viestinnän tavoitteena on muu kuin tuotteen myyntiin suorasti vaikuttaminen. Tuotesijoittelu on sen sijaan erittäin tehokas tuotetietoisuuden lisäämisessä, erityisesti tunnistamisen kohdalla. Tuotesijoittelu voi myös tuottaa suoran ostotarpeen mutta tällöin viestin vastaanottajalla täytyy olla vallitseva tarve kyseisen tuoteryhmän osalta ennen altistumista ko. markkinointiviestille. Tuotesijoittelu voidaan sisällyttää IMC-suunnitteluprosessiin markkinointiviestintästrategian kiinteänä osana. Integraatio markkinointiviestinnässä siten, että tuotesijoittelua tuettaisiin muilla viestintäkeinoilla yhtenäisen kampanjan kehittämiseksi on kuitenkin paljon ennakoitua harvinaisempaa, johtuen ehkä eniten tuotesijoittelun poikkeuksellisesta luonteesta ja kyseisen viestintämuodon vaikeasta hallittavuudesta markkinoijan taholta. Tutkimus toteutettiin normatiivisena case-tutkimuksena pääasiassa sekundäärisiä tietolähteitä hyödyntäen. Case-tutkimuksia varten kerättiin primääristä tietoa kyselylomakkeella kahdesta tuotesijoittelua käyttävästä kansainvälisestä yhtiöstä, jonka lisäksi myös sekundäärisiä tietolähteitä hyödynnettiin case-osan tiedonkeruussa.
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Formation of nanosized droplets/bubbles from a metastable bulk phase is connected to many unresolved scientific questions. We analyze the properties and stability of multicomponent droplets and bubbles in the canonical ensemble, and compare with single-component systems. The bubbles/droplets are described on the mesoscopic level by square gradient theory. Furthermore, we compare the results to a capillary model which gives a macroscopic description. Remarkably, the solutions of the square gradient model, representing bubbles and droplets, are accurately reproduced by the capillary model except in the vicinity of the spinodals. The solutions of the square gradient model form closed loops, which shows the inherent symmetry and connected nature of bubbles and droplets. A thermodynamic stability analysis is carried out, where the second variation of the square gradient description is compared to the eigenvalues of the Hessian matrix in the capillary description. The analysis shows that it is impossible to stabilize arbitrarily small bubbles or droplets in closed systems and gives insight into metastable regions close to the minimum bubble/droplet radii. Despite the large difference in complexity, the square gradient and the capillary model predict the same finite threshold sizes and very similar stability limits for bubbles and droplets, both for single-component and two-component systems.
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Uusissa ydinvoimalaitostyypeissä aiotaan käyttää aiempaa enemmän passiivisia turvallisuusjärjestelmiä. Näistä järjestelmistä on vielä vähän käyttökokemusta aktiivisiin turvallisuusjärjestelmiin verrattuna. Työssä tarkastellaan passiivisten turvallisuusjärjestelmien toimintaa sekä etsitään niiden mahdollisia luontaisia vikatilanteita. Luontaisten vikatilanteiden seurauksia järjestelmän suorituskykyyn arvioitiin yksinkertaisilla laskuilla ja mallintamalla RELAP5/MOD3.2.2 beta -termohydrauliikkaohjelmalla. Tarkastelu rajattiin kahden erityyppisen ydinvoimalaitoksen passiivisiin turvallisuusjärjestelmiin. Turvallisuusjärjestelmien suuntaa antavat mitat ja käyttötilanteiden parametrit saatiin laitosvalmistajien laitoskuvauksista. Osoittautui, että vikatilanteissa passiivisissa turvallisuusjärjestelmissä geometrialla on merkittävä vaikutus järjestelmän kapasiteettiin. Tarkasteluissa saatiin myös selville, että laitosmittakaavassa painovoimaisen hätälisävesijärjestelmän turvallisuustoiminto voi toteutua vaikka esiintyisi lyhytaikaisia toimintahäiriöitä, kuten lauhtumista hätälisävesisäiliössä. Sen sijaan lämmönsiirtopiirin virtausreittien tukkeutuminen voi olla fysikaalisesti merkittävä toimintaa haittaava tekijä.
Resumo:
Työn tavoitteena oli kehittää laajentumiskykyinen ja tarkka hajautettu mittajärjestelmä venymille ja vastaaville ilmiöille, joka silti kestäisi ankaria olosuhteita. Mittajärjestelmän tehtävä oli esittää keräämänsä tieto Internetissä. Työssä esitellään kehityksen avainkohdat. Työssä on käsitelty koko mittausjärjestelmän suunnitteluun vaikuttavien tekijöitten kaari. Esimerkki-ilmiönä käsitellään venymä. Esittelen sen fysikaalisen luonteen ja tavat joilla venymän rajat vaikuttavat mittausketjun vaatimuksiin. Samoin on esimerkein käsitelty itse anturointitapa ja sen häiriötyypit. Työ luo yhtenäisen matemaattisen katsauksen häiriöihin ja niiden hallitsemiseen ilmiöstä digitointivaiheeseen asti. Eri osa-alueiden häiriötekijät ilmaistaan valitun toisiinsa nivoutuvan terminologian kautta. Työ käsittelee tiedon digitoimisen ja verkottamisen problematiikkaa. Työssä verrataan tarjolla olleita vaihtoehtoja ja dokumentoidaan lopullisessa järjestelmässä käytetyt ratkaisut ja niiden valitsemisen syyt.
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Educational institutions are considered a keystone for the establishment of a meritocratic society. They supposedly serve two functions: an educational function that promotes learning for all, and a selection function that sorts individuals into different programs, and ultimately social positions, based on individual merit. We study how the function of selection relates to support for assessment practices known to harm vs. benefit lower status students, through the perceived justice principles underlying these practices. We study two assessment practices: normative assessment-focused on ranking and social comparison, known to hinder the success of lower status students-and formative assessment-focused on learning and improvement, known to benefit lower status students. Normative assessment is usually perceived as relying on an equity principle, with rewards being allocated based on merit and should thus appear as positively associated with the function of selection. Formative assessment is usually perceived as relying on corrective justice that aims to ensure equality of outcomes by considering students' needs, which makes it less suitable for the function of selection. A questionnaire measuring these constructs was administered to university students. Results showed that believing that education is intended to select the best students positively predicts support for normative assessment, through increased perception of its reliance on equity, and negatively predicts support for formative assessment, through reduced perception of its ability to establish corrective justice. This study suggests that the belief in the function of selection as inherent to educational institutions can contribute to the reproduction of social inequalities by preventing change from assessment practices known to disadvantage lowerstatus student, namely normative assessment, to more favorable practices, namely formative assessment, and by promoting matching beliefs in justice principles.
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En un article posterior a les seves traduccions a la llengua anglesa de Memorias de Leticia Valle de Rosa Chacel i de Delirio y destino de María Zambrano, Carol Maier apunta el que penso que hauria de constituir una de les màximes més determinants en la pràctica de la traducció (1996, 209): «…it is not only in the ‘text’ of a work but precisely in the notes, introductions, and afterwards meant to ensure a work’s recovery that the most decided re-covering often occurs.» Per a Maier, traductora literària, teòrica i professora de traducció, la responsabilitat de l’activitat traductològica no es limita a una mera (re)escriptura del text originari. Cal que el traductor i la traductora s’impliquin, abandonin les distàncies crítiques i portin a la visibilitat el que pensen sobre la teoria i la pràctica de la traducció. I és precisament aquesta crida de Maier a l’expansió del terme «responsabilitat» en traducció la que m’invita a presentar potser d’una altra manera aquesta entrevista amb ella. Maier ens ofereix ara i aquí un espai de debat, de diàleg i de reflexió per a totes les persones que volem pensar sobre les paradoxes i les contradiccions derivades de (re)escriure una textualitat en una altra llengua. En definitiva, estic convençuda que les seves afirmacions, pensaments i comentaris sobre les interseccions entre el gènere i la traducció es guanyaran merescudament el sobrenom de «responsables» per al qual ella lluita tan enèrgicament.
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The perceived low levels of genetic diversity, poor interspecific competitive and defensive ability, and loss of dispersal capacities of insular lineages have driven the view that oceanic islands are evolutionary dead ends. Focusing on the Atlantic bryophyte flora distributed across the archipelagos of the Azores, Madeira, the Canary Islands, Western Europe, and northwestern Africa, we used an integrative approach with species distribution modeling and population genetic analyses based on approximate Bayesian computation to determine whether this view applies to organisms with inherent high dispersal capacities. Genetic diversity was found to be higher in island than in continental populations, contributing to mounting evidence that, contrary to theoretical expectations, island populations are not necessarily genetically depauperate. Patterns of genetic variation among island and continental populations consistently fitted those simulated under a scenario of de novo foundation of continental populations from insular ancestors better than those expected if islands would represent a sink or a refugium of continental biodiversity. We, suggest that the northeastern Atlantic archipelagos have played a key role as a stepping stone for transoceanic migrants. Our results challenge the traditional notion that oceanic islands are the end of the colonization road and illustrate the significant role of oceanic islands as reservoirs of novel biodiversity for the assembly of continental floras.
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Given their high sensitivity and ability to limit the field of view (FOV), surface coils are often used in magnetic resonance spectroscopy (MRS) and imaging (MRI). A major downside of surface coils is their inherent radiofrequency (RF) B1 heterogeneity across the FOV, decreasing with increasing distance from the coil and giving rise to image distortions due to non-uniform spatial responses. A robust way to compensate for B1 inhomogeneities is to employ adiabatic inversion pulses, yet these are not well adapted to all imaging sequences - including to single-shot approaches like echo planar imaging (EPI). Hybrid spatiotemporal encoding (SPEN) sequences relying on frequency-swept pulses provide another ultrafast MRI alternative, that could help solve this problem thanks to their built-in heterogeneous spatial manipulations. This study explores how this intrinsic SPEN-based spatial discrimination, could be used to compensate for the B1 inhomogeneities inherent to surface coils. Experiments carried out in both phantoms and in vivo rat brains demonstrate that, by suitably modulating the amplitude of a SPEN chirp pulse that progressively excites the spins in a direction normal to the coil, it is possible to compensate for the RF transmit inhomogeneities and thus improve sensitivity and image fidelity.
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[eng] An observable study on the behaviour in the laboratory of Pharmaceutical Technology II (pharmaceutical pilot plant), with two groups of students of 3rd course (proactive aptitude and valuation of the"knowledge to do acquired") is carried out. The variable between groups is that one has realised a training (by means of self-study of an interactive application multimedia, especially designed), without tutorship on behalf the teacher in front of the other group that carried out the same training with the same material but with the guide of the teacher in the computer lab. On the one hand it is valued if there is some effect differentiator between both types of training, by means of the accounting of the correct results obtained in a previous test to the entrance in the pilot plant and by another one the valuation that the professors made responsible for the groups of practices in situ. The results demonstrate the previous hypothesis that there must not be significant differences between the groups, beyond the inherent ones to personality of the students itself (interest and personal implication by the subject). On the other hand the test for the observation in the laboratory did not facilitate the distinction of objective differences. [spa] Se lleva a cabo un estudio observacional sobre el comportamiento de los estudiantes (aptitud pro-activa y valoración del “saber hacer adquirido”) en el laboratorio de Tecnología Farmacéutica II (planta piloto farmacéutica) de dos grupos de estudiantes de 3er curso. La variable entre los dos grupos es que uno ha realizado una formación no presencial (mediante el autoestudio de una aplicación interactiva multimedia, especialmente diseñada), sin tutoría por parte del profesor, frente al otro grupo que llevó a cabo la misma formación con el mismo material pero con la guía del profesor en el aula de informática. Por una parte se valora si hay algún efecto diferenciador entre ambos tipos de formación, mediante la contabilización de los resultados correctos obtenidos en un test previo a la entrada en la planta piloto y por otro la valoración que hicieron los profesores responsables de los grupos de prácticas in situ. Los resultados demuestran la hipótesis previa de que no debían existir diferencias significativas entre los grupos, más allá de las inherentes a la propia personalidad de los estudiantes (interés e implicación personal por el tema). Por otra parte el test para la observación en el laboratorio no facilitó la distinción de diferencias objetivas.
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The question of how to quantify insufficient coping behavior under chronic stress is of major clinical relevance. In fact, chronic stress increasingly dominates modern work conditions and can affect nearly every system of the human body, as suggested by physical, cognitive, affective and behavioral symptoms. Since freshmen students experience constantly high levels of stress due to tight schedules and frequent examinations, we carried out a 3-center study of 1,303 students from Italy, Spain and Argentina in order to develop socioculturally independent means for quantifying coping behavior. The data analysis relied on 2 self-report questionnaires: the Coping Strategies Inventory (COPE) for the assessment of coping behavior and the Zurich Health Questionnaire which assesses consumption behavior and general health dimensions. A neural network approach was used to determine the structural properties inherent in the COPE instrument. Our analyses revealed 2 highly stable, socioculturally independent scales that reflected basic coping behavior in terms of the personality traits activity-passivity and defeatism-resilience. This replicated previous results based on Swiss and US-American data. The percentage of students exhibiting insufficient coping behavior was very similar across the study sites (11.5-18.0%). Given their stability and validity, the newly developed scales enable the quantification of basic coping behavior in a cost-efficient and reliable way, thus clearing the way for the early detection of subjects with insufficient coping skills under chronic stress who may be at risk of physical or mental health problems.
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Two cost-efficient genome-scale methodologies to assess DNA-methylation are MethylCap-seq and Illumina's Infinium HumanMethylation450 BeadChips (HM450). Objective information regarding the best-suited methodology for a specific research question is scant. Therefore, we performed a large-scale evaluation on a set of 70 brain tissue samples, i.e. 65 glioblastoma and 5 non-tumoral tissues. As MethylCap-seq coverages were limited, we focused on the inherent capacity of the methodology to detect methylated loci rather than a quantitative analysis. MethylCap-seq and HM450 data were dichotomized and performances were compared using a gold standard free Bayesian modelling procedure. While conditional specificity was adequate for both approaches, conditional sensitivity was systematically higher for HM450. In addition, genome-wide characteristics were compared, revealing that HM450 probes identified substantially fewer regions compared to MethylCap-seq. Although results indicated that the latter method can detect more potentially relevant DNA-methylation, this did not translate into the discovery of more differentially methylated loci between tumours and controls compared to HM450. Our results therefore indicate that both methodologies are complementary, with a higher sensitivity for HM450 and a far larger genome-wide coverage for MethylCap-seq, but also that a more comprehensive character does not automatically imply more significant results in biomarker studies.
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Laboratory and field experiments have demonstrated in many cases that malaria vectors do not feed randomly, but show important preferences either for infected or non-infected hosts. These preferences are likely in part shaped by the costs imposed by the parasites on both their vertebrate and dipteran hosts. However, the effect of changes in vector behaviour on actual parasite transmission remains a debated issue. We used the natural associations between a malaria-like parasite Polychromophilus murinus, the bat fly Nycteribia kolenatii and a vertebrate host the Daubenton's bat Myotis daubentonii to test the vector's feeding preference based on the host's infection status using two different approaches: 1) controlled behavioural assays in the laboratory where bat flies could choose between a pair of hosts; 2) natural bat fly abundance data from wild-caught bats, serving as an approximation of realised feeding preference of the bat flies. Hosts with the fewest infectious stages of the parasite were most attractive to the bat flies that did switch in the behavioural assay. In line with the hypothesis of costs imposed by parasites on their vectors, bat flies carrying parasites had higher mortality. However, in wild populations, bat flies were found feeding more based on the bat's body condition, rather than its infection level. Though the absolute frequency of host switches performed by the bat flies during the assays was low, in the context of potential parasite transmission they were extremely high. The decreased survival of infected bat flies suggests that the preference for less infected hosts is an adaptive trait. Nonetheless, other ecological processes ultimately determine the vector's biting rate and thus transmission. Inherent vector preferences therefore play only a marginal role in parasite transmission in the field. The ecological processes rather than preferences per se need to be identified for successful epidemiological predictions.