Drying Kinetics of Oca (Oxalis Tuberosa)

One of the most important steps for agro-industrial industrialization is examining the kinetic behavior of products, to determine the ideal parameters to maintain their characteristics throughout the production chain. This study experimentally determined the drying kinetics of oca, an indigenous product of the Andean region, because there is no established information on the drying techniques of this tuber. The Andean region is the cradle of a large number of food crops that were domesticated and exploited by indigenous people thousands of years ago, even long before the expansion of the Inca civilization. In Ecuador, oca is perhaps the most important element of the daily diet, and an acceptable level of purity and hygiene has been reached. Oca provides fiber, essential amino acids and a low level of fat. In this study, a temperature of 60ºC was set at the beginning of each experimental run. The weight of the oca slices was measured every 10 min. The experiments were carried out in triplicate. Data were analyzed using StatGraphics software. Two drying periods were observed: the initial period of constant drying speed, where the removal of moisture corresponded to moisture not linked to the oca, while in the second stage, the internal moisture of the tuber was removed. Keywords: kinetic, drying, goose. RESUMEN Uno de los pasos más importantes para la industrialización agroindustrial es el comportamiento cinético de productos, esto en especial para conocer cuáles son los parámetros ideales para mantener las características sensoriales durante toda la cadena de producción. El presente documento determina experimentalmente la cinética de secado para un producto autóctono de la Región Andina, como lo es la oca, puesto que no existe información sobre las técnicas de secado de este tubérculo. En el Ecuador se ha alcanzado un aceptable nivel de pureza e higiene, la Oca es quizás el elemento más importante de la dieta diaria. La región andina es cuna de un gran número de cultivos alimenticios que fueron domesticados y aprovechados por pueblos autóctonos hace miles de años, inclusive mucho antes de la expansión de la civilización Inca. Aporta fibra, aminoácidos esenciales y un nivel bajo en grasa. La experimentación para conocer las curvas que modelan el comportamiento cinético del secado, se llevó a cabo por triplicado; luego de realizar la recolección de datos, estos fueron analizados utilizando el software estadístico StatGraphics. donde se obtuvo el respectivo análisis de varianza y las curvas. En el estudio se configuró una temperatura de 60ºC al inicio de cada corrida experimental, Se midió el peso de las rodajas de Oca cada 10 min, los datos fueron registrados y se procesó las tablas resultantes. En el estudio se pudo observar dos periodos de secado: Periodo inicial de velocidad de secado constante, donde la eliminación de humedad corresponde a la humedad no ligada a la oca, mientras en la segunda etapa se eliminó la humedad interna del tubérculo. Palabras claves: cinética, secado, oca

Double parton interactions in photon+3 jet events in ppbar collisions sqrt{s}=1.96 TeV

We have used a sample of photon+3 jets events collected by the D0 experiment with an integrated luminosity of about 1 fb^-1 to determine the fraction of events with double parton scattering (f_DP) in a single ppbar collision at sqrt{s}=1.96 TeV. The DP fraction and effective cross section (sigma_eff), a process-independent scale parameter related to the parton density inside the nucleon, are measured in three intervals of the second (ordered in pT) jet transverse momentum pT_jet2 within the range 15 < pT_jet2 < 30 GeV. In this range, f_DP varies between 0.23 < f_DP < 0.47, while sigma_eff has the average value sigma_eff_ave = 16.4 +- 0.3(stat) +- 2.3(syst) mb.Comment: 15 pages, 13 figure

Dependence of the ttˉt\bar{t} production cross section on the transverse momentum of the top quark

We present a measurement of the differential cross section for $t\bar{t}$ events produced in $p\bar{p}$ collisions at $\sqrt{s}=1.96$ TeV as a function of the transverse momentum ($p_T$) of the top quark. The selected events contain a high-$p_T$ lepton ($\ell$), four or more jets, and a large imbalance in $p_T$, and correspond to 1 fb${}^{-1}$ of integrated luminosity recorded with the D0 detector. Each event must have at least one candidate for a $b$ jet. Objects in the event are associated through a constrained kinematic fit to the $t\bar{t}\to WbW\bar{b} \to \ell\nu b q\bar{q}'\bar{b}$ process. Results from next-to-leading-order perturbative QCD calculations agree with the measured differential cross section. Comparisons are also provided to predictions from Monte Carlo event generators using QCD calculations at different levels of precision.Comment: 8 pages, 6 figures, 4 tables, updated to reflect the published versio

The ROSAT International X-ray/Optical Survey (RIXOS): source catalogue

We describe the ROSAT International X-ray/Optical Survey (RIXOS), a medium-sensitivity survey and optical identification of X-ray sources discovered in ROSAT high Galactic latitude fields (|b|>28°) and observed with the Position Sensitive Proportional Counter (PSPC) detector. The survey made use of the central 17 arcmin of each ROSAT field. A flux limit of 3×10−14 erg cm−2 s−1 (0.5–2 keV) was adopted for the survey, and a minimum exposure time of 8000 s was required for qualifying ROSAT observations. X-ray sources in the survey are therefore substantially above the detection threshold of each field used, and many contain enough counts to allow the X-ray spectral slope to be estimated. Spectroscopic observations of potential counterparts were obtained of all sources down to the survey limit in 64 fields, totalling a sky area of 15.77 deg2. Positive optical identifications are made for 94 per cent of the 296 sources thus examined. A further 18 fields (4.44 deg2), containing 105 sources above the 3×10−14 erg cm−2 s−1 survey limit, are completely optically identified to a higher flux of 8×10−14 erg cm−2 s−1 (0.5–2 keV). Optical spectroscopic data are supplemented by deep CCD imaging of many sources to reveal the morphology of the optical counterparts, and objects too faint to register on Sky Survey plates. The faintest optical counterparts have R∼22. This paper describes the survey method, and presents a catalogue of the RIXOS sources and their optical identifications. Finding charts based on Sky Survey data are given for each source, supplemented by CCD imaging where necessary

Search for the associated production of a b quark and a neutral supersymmetric Higgs boson which decays to tau pairs

We report results from a search for production of a neutral Higgs boson in association with a $b$ quark. We search for Higgs decays to $\tau$ pairs with one $\tau$ subsequently decaying to a muon and the other to hadrons. The data correspond to 2.7fb$^{-1}$ of \ppbar collisions recorded by the D0 detector at $\sqrt{s} = 1.96$TeV. The data are found to be consistent with background predictions. The result allows us to exclude a significant region of parameter space of the minimal supersymmetric model.Comment: Submitted to Phys. Rev. Letter

Search for New Physics with Jets and Missing Transverse Momentum in pp collisions at sqrt(s) = 7 TeV

A search for new physics is presented based on an event signature of at least three jets accompanied by large missing transverse momentum, using a data sample corresponding to an integrated luminosity of 36 inverse picobarns collected in proton--proton collisions at sqrt(s)=7 TeV with the CMS detector at the LHC. No excess of events is observed above the expected standard model backgrounds, which are all estimated from the data. Exclusion limits are presented for the constrained minimal supersymmetric extension of the standard model. Cross section limits are also presented using simplified models with new particles decaying to an undetected particle and one or two jets