In Favor of Rigor and Relevance. A Reply to Mark Blaug

The paper discusses Mark Blaug’s recent criticisms of “Sraffian economics”. It is shown that none of the criticisms stand up to close examination. Blaug commits a number of elementary blunders and mistakes the mathematical form of an argument for its content. He variously contradicts himself and puts forward bold contentions that cannot be sustained. The paper concludes with an obvious plea for rigor and relevance.Piero Sraffa;Mark Blaug; General Equilibrium

High-resolution [C II] imaging of HDF850.1 reveals a merging galaxy at z=5.185

New high-resolution maps with the IRAM Interferometer of the redshifted [C II] 158 micron line and the 0.98mm dust continuum of HDF850.1 at z = 5.185 show the source to have a blueshifted northern component and a redshifted southern component, with a projected separation of 0.3 arcsec, or 2 kpc. We interpret these components as primordial galaxies that are merging to form a larger galaxy. We think it is the resulting merger-driven starburst that makes HDF850.1 an ultraluminous infrared galaxy, with an L(IR) of 1E13 Lsun. The observed line and continuum brightness temperatures and the constant line-to-continuum ratio across the source imply (1) high [C II] line optical depth, (2) a [C II] excitation temperature of the same order as the dust temperature, and (3) dust continuum emission that is nearly optically thick at 158 microns. These conclusions for HDF850.1 probably also apply to other high-redshift submillimeter galaxies and quasar hosts in which the [C II] 158 micron line has been detected, as indicated by their roughly constant [C II]-to-158 micron continuum ratios, in sharp contrast to the large dispersion in their [C II]-to-FIR luminosity ratios. In brightness temperature units, the [C II] line luminosity is about the same as the predicted CO(1-0) luminosity, implying that the [C II] line can also be used to estimate the molecular gas mass, with the same assumptions as for CO.Comment: Accepted by Astronomy and Astrophysic

Autocatalytic reaction-diffusion processes in restricted geometries

We study the dynamics of a system made up of particles of two different species undergoing irreversible quadratic autocatalytic reactions: $A + B \to 2A$. We especially focus on the reaction velocity and on the average time at which the system achieves its inert state. By means of both analytical and numerical methods, we are also able to highlight the role of topology in the temporal evolution of the system

Reset and switch protocols at Landauer limit in a graphene buckled ribbon

Heat produced during a reset operation is meant to show a fundamental bound known as Landauer limit, while simple switch operations have an expected minimum amount of produced heat equal to zero. However, in both cases, present-day technology realizations dissipate far beyond these theoretical limits. In this paper we present a study based on molecular dynamics simulations, where reset and switch protocols are applied on a graphene buckled ribbon, employed here as a nano electromechanical switch working at the thermodynamic limit

Universal features of information spreading efficiency on dd-dimensional lattices

A model for information spreading in a population of $N$ mobile agents is extended to $d$-dimensional regular lattices. This model, already studied on two-dimensional lattices, also takes into account the degeneration of information as it passes from one agent to the other. Here, we find that the structure of the underlying lattice strongly affects the time $\tau$ at which the whole population has been reached by information. By comparing numerical simulations with mean-field calculations, we show that dimension $d=2$ is marginal for this problem and mean-field calculations become exact for $d > 2$. Nevertheless, the striking nonmonotonic behavior exhibited by the final degree of information with respect to $N$ and the lattice size $L$ appears to be geometry independent.Comment: 8 pages, 9 figure

Autocatalytic reaction-diffusion processes in restricted geometries

We study the dynamics of a system made up of particles of two different species undergoing irreversible quadratic autocatalytic reactions: $A + B \to 2A$. We especially focus on the reaction velocity and on the average time at which the system achieves its inert state. By means of both analytical and numerical methods, we are also able to highlight the role of topology in the temporal evolution of the system

Discovery of Water Vapor in the High-redshift Quasar APM 08279+5255 at z = 3.91

We report a detection of the excited 2_(20)-2_(11) rotational transition of para-H_2O in APM 08279+5255 using the IRAM Plateau de Bure Interferometer. At z = 3.91, this is the highest-redshift detection of interstellar water to date. From large velocity gradient modeling, we conclude that this transition is predominantly radiatively pumped and on its own does not provide a good estimate of the water abundance. However, additional water transitions are predicted to be detectable in this source, which would lead to an improved excitation model. We also present a sensitive upper limit for the hydrogen fluoride (HF) J = 1-0 absorption toward APM 08279+5255. While the face-on geometry of this source is not favorable for absorption studies, the lack of HF absorption is still puzzling and may be indicative of a lower fluorine abundance at z = 3.91 compared with the Galactic interstellar medium

Immobilization of β-galactosidase onto different water insoluble matrices

Tese de Doutoramento em Engenharia Química e Biológica - Área de Conhecimento Engenharia Enzimática e das FermentaçõesEsta tese de Doutoramento é o resultado de um projecto de colaboração entre a Universidade Federal de Pernambuco, Brasil e a Universidade do Minho, Portugal, financiado pelo Programa Alßan de bolsas de estudo de alto nível destinado à América Latina. Lactases ou β-galactosidases (E.C. 3.2.1.23) são enzimas com um elevado interesse industrial quer na conversão da lactose em galactose e glicose quer na síntese de oligossacarídeos. O seu uso tem sido recomendado para hidrolisar a lactose no leite consumido por aqueles indivíduos com intolerância à lactose, na manufactura de sorvete e na produção de galactooliossacarídeos (GOS), compostos que se inserem nos denominados alimentos funcionais (pré-bióticos). A imobilização desta biomolécula em suportes de baixo custo, mediante procedimentos de fácil execução, pode potenciar a eficiência catalítica do derivado enzimático por causa da melhor estabilidade ao pH e temperatura, proporcionando deste modo, menores custos operacionais e aumentando suas aplicações biotecnológicas em indústrias de alimentos. O principal objectivo do trabalho desenvolvido foi avaliar a utilização de β-galactosidase imobilizada em diferentes matrizes insolúveis em água tanto na hidrólise da lactose como na síntese de GOS. No decorrer do trabalho, foram usados quatro suportes magnéticos: (1) polisiloxano-Álcool Polivinílico magnético – mPOS-PVA; (2) magnetita revestida com polianilina – MAG-PANI; (3) polisiloxano revestido com polianilina – POS-PANI e (4) Dacron magnetizado. β-Galactosidase de duas origens diferentes (Kluyveromyces lactis e Aspergillus oryzae) foram usadas. Todas as matrizes investigadas foram adequadas para a imobilização de β-galactosidase e para a produção de GOS usando lactose como substrato. A capacidade de formação de GOS pela enzima não foi afectada pela imobilização nos diferentes suportes magnéticos, não se tendo observado diferenças na cinética reaccional de síntese entre a enzima livre e a enzima imobilizada nos diferentes suportes. A caracterização físico-quimica dos suportes contendo a enzima imobilizada permitiu confirmar a ausência de limitações difusionais à transferência de massa. Verificou-se também que a produção de GOS, a diferentes temperaturas 30 – 60ºC, foi praticamente inalterada, tanto para a enzima livre quanto para a imobilizada. Comparando a eficiência de imobilização dos diferentes suportes, verificou-se que a maior retenção de actividade enzimática de hidrólise e de síntese foi obtida com a enzima imobilizada em Dacron magnetizado. Foi também desenvolvido um modelo matemático que descreve adequadamente as reacções de hidrólise da lactose e síntese de GOS e efectuada a caracterização química, física e estrutural dos suportes MAG-PANI e POS-PANI.This PhD thesis is the result of a collaboration project between the Universidade Federal de Pernambuco, Brazil, and the Universidade do Minho, Portugal, financed by the Programme Alßan, a high level scholarship programme specifically addressed to Latin America. Lactases or β-galactosidases (E.C. 3.2.1.23) are enzymes with an increasing industrial importance for lactose hydrolysis and for oligosaccharides synthesis. Its use has been recommended for the hydrolysis of lactose in milk consumed by lactose intolerant individuals, for ice-cream manufacture and in the production of galactooligosaccharides (GOS), compounds known as functional foods (prebiotics). The immobilization of β-galactosidase onto low-cost matrices by ease procedures can enhance the catalysis efficiency of the enzymatic derivatives because of the greater stability to pH and temperature, providing thus lower operational costs and increasing their applications in food industry biotechnology. The main objectives of the developed work were to evaluate the immobilization of β-galactosidase onto different water insoluble matrices both for lactose hydrolysis and GOS synthesis. Four magnetic matrices were used for enzyme immobilization: (1) polyvinyl alcohol polysiloxane-magnetic - mPOS-PVA; (2) magnetite coated with polyaniline - MAG-PANI; (3) polysiloxane coated with polyaniline - POS-PANI and (4) ferromagnetic Dacron. β-galactosidase from two different origins (Kluyveromyces lactis and Aspergillus oryzae) were used. All the investigated matrices were suitable for the β-galactosidase immobilization and the GOS production as well, using lactose as substrate. The ability of GOS formation by the enzyme was not affected by the immobilization on the different magnetic matrices and no differences on the kinetics of GOS synthesis were observed between immobilized and free enzymes. The physic-chemical characterization of the supports with the immobilized enzymes allowed the conclusion that diffusional mass transfer limitations were not a concern. It was observed that GOS production in the temperature range of 30 - 60 º C was unchanged for both free and for immobilized enzyme. In what concerns β-galactosidase immobilization efficiency of the different supports, it was conclude that magnetized Dacron allowed for the highest activity retention both for hydrolysis and synthesis. Furthermore, a mathematical model describing lactose hydrolysis and GOS synthesis was developed and a detailed chemical, physical and structural characterization of the MAG-PANI and POS-PANI supports was done.Program Alban - E05D057787BR