Microgravity acoustic mixing for particle cloud combustors

Experimental and theoretical investigations of acoustic mixing procedures designed to uniformly distribute fuel particles in a combustion tube for application in the proposed Particle Cloud Combustion Experiment (PCCE) are described. Two acoustic mixing methods are investigated: mixing in a cylindrical tube using high frequency spinning modes generated by suitably phased, or quadrature speakers, and acoustic premixing in a sphere. Quadrature mixing leads to rapid circumferential circulation of the powder around the tube. Good mixing is observed in the circulating regions. However, because axial inhomogeneities are necessarily present in the acoustic field, this circulation does not extend throughout the tube. Simultaneous operation of the quadrature-speaker set and the axial-speaker was observed to produce considerably enhanced mixing compared to operation of the quadrature-speaker set alone. Mixing experiments using both types of speakers were free of the longitudinal powder drift observed using axial-speakers alone. Vigorous powder mixing was obtained in the sphere for many normal modes: however, in no case was the powder observed to fill the sphere entirely. Theoretical analysis indicated that mixing under steady conditions cannot fill more than a hemisphere except under very unusual conditions. Premixing in a hemisphere may be satisfactory; otherwise, complete mixing in microgravity might be possible by operating the speaker in short bursts. A general conclusion is that acoustic transients are more likely to produce good mixing than steady state conditions. The reason is that in steady conditions, flow structures like nodal planes are possible and often even unavoidable. These tend to separate the mixing region into cells across which powder cannot be transferred. In contrast, transients not only are free of such structures, they also have the characteristics, desirable for mixing, of randomness and disorder. This conclusion is corroborated by mixing experiments using axial waves

A phylogenetic comparative analysis on the evolution of sequential hermaphroditism in seabreams (Teleostei : Sparidae)

The Sparids are an ideal group of fish in which to study the evolution of sexual systems since they exhibit a great sexual diversity, from gonochorism (separate sexes) to protandrous (male-first) and protogynous (female-first) sequential hermaphroditism (sex-change). According to the size-advantage model (SAM), selection should favour sex change when the second sex achieves greater reproductive success at a larger body size than the first sex. Using phylogenetic comparative methods and a sample of 68 sparid species, we show that protogyny and protandry evolve from gonochorism but evolutionary transitions between these two forms of sequential hermaphroditism are unlikely to happen. Using male gonadosomatic index (GSI) as a measure of investment in gametes and proxy for sperm competition, we find that, while gonochoristic and protogynous species support the predictions of SAM, protandrous species do not, as they exhibit higher GSI values than expected even after considering mating systems and spawning modes. We suggest that small males of protandrous species have to invest disproportionally more in sperm production than predicted not only when spawning in aggregations with high levels of sperm competition, but also when spawning in pairs due to the need to fertilize highly fecund females, much larger than themselves. We propose that this compensatory mechanism, together with Bateman’s principles in sequential hermaphrodites, should be formally incorporated in the SAM

La demolingüística en els territoris de llengua catalana

L'article comença per indicar on va néixer la demolingüística i per què es va produir aquest esdeveniment. També explica comel seu cultiu s'ha anat expandint posteriorment pelmón.Després es parla, més a fons, de l'aparició de la disciplina en el domini del català, i sobretot de la seva evolució en aquest àmbit, evolució que es divideix en quatre etapes; dues d'aquestes etapes se situen en el segle passat i les altres dues en l'actual segle XXI. Posteriorment, es concreten els temes principals de què s'ocupa la demolingüística en l'àrea del català i es finalitza presentant alguns del reptes que té plantejats la disciplina.Demolinguistics in Catalan-speaking territories. The article starts by explaining the origins of “demolinguistics” and the reasons behind its emergence and goes on to assess how it has stretched to other parts of the world. The paper then goes into further depth on the emergence of this discipline in the Catalan language domain and, in particular, its evolution in this sphere. This evolution is divided into four stages; two of them date back to the past century and the other two date from the 21st century. The paper then outlines themain issues that demolinguistics deals with in the Catalan sphere and, to conclude, it lists a number of key challenges that the discipline faces

Estudi epidemiològic de la depressió major en infants de 3-6 anys

Consultable des del TDXTítol obtingut de la portada digitalitzadaNo sabem gaire de les característiques de la depressió major entre els 3 i 6 anys de vida. Actualment s'utilitzen els mateixos criteris diagnòstics que en els adults així com es recull la mateixa simptomatologia. Els escassos estudis actuals, apunten a la necessitat de crear uns criteris específics que incloguin i donin major rellevància a uns determinats símptomes més propis pels infants d'entre 3 a 6 anys. Quan el que volem és saber la prevalença de depressió major a en aquestes edats, trobem valors al voltant del 0,9 % en població general, tot i que en el nostre país no hi havia cap dada. OBJECTIUS: Aquesta investigació, té per objectiu estudiar la prevalença de la depressió major entre els 3 i 6 anys, així com les seves característiques. SUBJECTES: Es parteix d'una mostra escolar de 460 infants que cursen P3, P4 i P5 a Olot. S'han confeccionat dos grups a partir de la puntuació en l'instrument ESDM 3-6 omplert per la mestra, amb un total de 132 nens. PROCEDIMENT L'estudi s'ha realitzat en tres fases. En la primera, a partir d'una puntuació igual o superior a 27 en l'ESDM, s'obté un grup amb alta simptomatologia depressiva (N= 72) així com es forma un grup control (N=60). Aquest grup control s'ha seleccionat en funció del nombre de casos amb simptomatologia alta, el sexe, curs escolar i aula. S'han passat instruments als pares i al mateix nen. Finalment s'ha realitzat una entrevista clínica de comú acord entre dos clínics, per tal de determinar el diagnòstic. RESULTATS: Un 0,87% de la mostra presenta depressió major en base a criteris DSM-IV (APA; 1995). No s'observen diferències en funció del sexe, classe socioeconòmica, escola ni curs, mentre és rellevant l'alta simptomatologia depressiva de la mare. Com a símptomes els nens amb depressió, solen presentar els mateixos símptomes recollits en el DSM-IV excepte alteracions en l'alimentació, son i sentiments d'inutilitat i culpa. Per altre banda, es troben símptomes que es presenten de forma significativa en els infants amb depressió major que no estan recollits en el DSM-IV, com són la dificultat en el control d'esfinters, la inhibició conductual i les somatitzacions, el que ens planteja la necessitat de tenir uns criteris adaptats per aquesta edat. DISCUSSIÓ: L'índex de depressió major trobat en aquesta mostra es troba dins la linea de la resta d'estudis. Aquest valor és inferior al trobat en edats superiors. Aquest estudi ha permès observar i destacar, a l'igual que Luby et al (2002), que el nen preescolar pot presentar anhedonia com l'adult, així com una simptomatologia propia per aquesta etapa evolutiva. Seria interessant i necessari revisar els criteris diagnòstics de depressió major així com estudiar el pes d'alguns d'aquests símptomes com la inhibició conductual o la dificultat en el control d'esfinters (símptomes rellevants en el nostre estudi). Com a variables relacionades, s'ha destacat l'alta simptomatologia depressiva en les mares dels nens amb simptomatologia depressiva alta i en els casos amb depressió major clínica, així com la vivència d'un esdeveniment estressant. No obstant, ni el sexe, edat, situació sociofamiliar, ni tipus d'escola han presentant diferències significatives entre els grups. CONCLUSIÓ: Trobem un 15,8% d'infants de 3 a 6 anys, amb simptomatologia depressiva alta. L'índex de prevalença de depressió major clínica, és del 0,87% seguint els criteris DSM-IV. Hi ha variables familiars com la depressió materna i viure un esdeveniment estressant que es relacionen amb la presència de depressió major en el nen.We don't know much about the features of major depression in 3 to 6 year-olds. Nowadays,the same diagnostical criteria than in adults are used and so are the same symptoms collected. The lack of present studies is due to the need of creating specific criteria which include and give more relevance to certain symptoms associated to 3 and 6 year-olds.When we want to know about the prevalence of major depression at this age, we find rates around 0,9% in average population, although there are no data in our country.OBJECTIVES, AIMS. The aim of this research is to study the prevalence of major depression in 3 and 6 year-olds and set its characteristics.SUBJECTS. The sample has been taken from 460 infants of a nursery school ( P3,P4 i P5) in Olot. Two groups have been made out of the score obtained from an instrument ESDM3-6 filled by the teacher , with a total of 132 children. PROCEDURE. There have been three phases. In the first one, from a score equal or superior to 27 in ESDM, a group with high depressive symptoms(N=72) , as well as a control group (N=60).This control group has been selected according to the number of cases with high symptoms, sex, school year and classroom.Instruments have been filled by both parents and children. Finally, a clinical interview within 2 doctors has been agreed so as to determine the diagnosis. RESULTS. O,87% of the sample presents major depression based on DSM-IV criteria( APA,1995). We do not observe differences according to sex, socio-economical class, school or school year but high depression in the mother is relevant. The symptoms of children with depression are the same as the ones collected in DSM-IV , except food and sleep irregularities, feeling of uselessness and guilt.On the other hand, we find symptoms in children with major which are not collected in DSM-IV , such as the difficulty in controlling sphincters , behavioural inhibition and characterisations.All this raises the need of having criteria adapted to this age. DISCUSSION. Major depression rates found in this sample are in the lines of other research. This value is inferior to the one found in older children. This research has allowed to observe and highlight, like Luby&al.(2002), that children at nursery-school age can present anhedonia when becoming an adult , as well as symptoms of this evolutive age.It would be interesting and necessary to revise diagnostical criteria of major depression and study the importance of some of these symptoms such as conductual inhibition or the difficulty of controlling sphincters ( relevant symptoms in our research). As related features , we have to highlight high depressive symptoms in mothers of children with high depressive symptoms and in cases of major clinical depression, as well as going through a stressful experience . Nevertheless, sex ,age, socio-familiar situation or kind of school have not presented significant differences among groups. CONCLUSION. 15,8% of 3 to 6 year-olds have presented high depressive symptoms. The rate of prevalence of major clinical depression is 0,87% following DSM-IV criteria. Family features like mother's depression and going through a stressful experience have been related to major depression in children

Jeroni Pujades: cronista i literat per evadir-se d’una praxi del dret poc estimulant?

La documentació localitzada en diversos arxius de Barcelona, Girona i Castelló d’Empúries sobre la praxi de Jeroni Pujades com a advocat o com a assessor jurisdiccional en diverses institucions i cúries és prou abundant. I, sobretot, és il·lustrativa d’una quotidianitat sovint poc estimulant i de subsistència. Pujades se n’evadirà sempre que pugui per viure la seva realitat paral·lela, il·luminada amb històries, corresponsals, inscripcions lapidàries i numismàtiques, cròniques i dietaris. Abstract The documents located in the archives of Barcelona, Girona and Castelló d’Empúries about the praxi of Jeroni Pujades as a lawyer or as a judicial advisor in different institutions and curiae is plenty. And in particular it demonstrates how his work was often unattractive. Considering this, it is understandable that he prefered to spend his time reading epigraphical inscriptions, exchanging letters with people throughout Catalonia and writing his famous Chronicles and Dietaries