15,222 research outputs found
Statistical power analysis with microsoft excel: normal tests for one or two means as a prelude to using non-central distributions to calculate power
This article presents statistical power analysis (SPA) based on the normal distribution using Excel, adopting textbook and SPA approaches. The objective is to present the latter in a comparative way within a framework that is familiar to textbook level readers, as a first step to understand SPA with other distributions. The analysis focuses on the case of the equality of the means of two populations with equal variances for independent samples with the same size. This is the situation adopted as case 0 by Cohen (1988), a pioneer in the subject, to develop his set of tables and so, the present article can be seen as an introduction to Cohen's methodology applied to tests based on samples from normal populations. We also discuss how to extend the calculation to cases with other characteristics (cases 1 to 4), similarly to what Cohen proposes, as well as a brief discussion about the advantages and shortcomings of Excel. We teach mainly in the area of business and economics, which determines the scope of our analysis.info:eu-repo/semantics/publishedVersio
High Resolution 4.7 um Keck/NIRSPEC Spectra of Protostars. I: Ices and Infalling Gas in the Disk of L1489 IRS
We explore the infrared M band (4.7 um) spectrum of the class I protostar
L1489 IRS in the Taurus Molecular Cloud. This is the highest resolution wide
coverage spectrum at this wavelength of a low mass protostar observed to date
(R=25,000; Dv=12 km/s). Many narrow absorption lines of gas phase 12CO, 13CO,
and C18O are detected, as well as a prominent band of solid 12CO. The gas phase
12CO lines have red shifted absorption wings (up to 100 km/s), likely
originating from warm disk material falling toward the central object. The
isotopes and the 12CO line wings are successfully fitted with a contracting
disk model of this evolutionary transitional object (Hogerheijde 2001). This
shows that the inward motions seen in millimeter wave emission lines continue
to within ~0.1 AU from the star. The colder parts of the disk are traced by the
prominent CO ice band. The band profile results from CO in 'polar' ices (CO
mixed with H2O), and CO in 'apolar' ices. At the high spectral resolution, the
'apolar' component is, for the first time, resolved into two distinct
components, likely due to pure CO and CO mixed with CO2, O2 and/or N2. The ices
have probably experienced thermal processing in the upper disk layer traced by
our pencil absorption beam: much of the volatile 'apolar' ices has evaporated
and the depletion factor of CO onto grains is remarkably low (~7%). This study
shows that high spectral resolution 4.7 um observations provide important and
unique information on the dynamics and structure of protostellar disks and the
evolution of ices in these disks.Comment: 11 pages, 6 figures Scheduled to appear in ApJ 568 n2, 1 April 200
Extension of Tycho catalog for low-extinction windows in the galactic bulge
We present in this work secondary catalogs up to based on
the Tycho reference frame (ESA, 1997) for 12 selected low-extinction fields
towards the galactic bulge. The observations have been performed with the
Askania-Zeiss Meridian Circle equiped with a CCD camera, located at the
Abrah\~ao de Moraes Observatory (Valinhos, Brazil) and operated by the
Institute of Astronomy and Geophysics, S\~ao Paulo University. The presented
catalog, though not complete, has been designed to help in intensive search
programmes (e.g. microlensing and variable searches) and therefore the selected
standards have a high astrometric and photometric ( band, approximately)
quality. The mean precisions obtained were in , 0.013'' in
, 0.030 for the standard deviation in magnitude and 0.0042 for the
magnitude when weighted with the error bars in each night (in the mean, 42
stars for the catalog of each window). Tables B.1 to B.12 are also available in
eletronic form at the CDS via anonymous ftp to cdsarc.u-strasbg.fr
(130.79.128.5) or via http://cdsweb.u-strasbg.fr/Abstract.html.Comment: 16 pages, 6 figures, A&A Latex style. Published in A&A
Stellar variability in low-extinction regions towards the Galactic Bulge
Intensive monitoring of low-extinction windows towards the galactic bulge has
provided in the last years valuable information for studies about the dynamics,
kinematics and formation history of this part of the galaxy, mainly by
characterizing the bulge stellar populations (Paczy\'nski, 1996). Since 1997,
we have been conducting an intensive photometric-astrometric survey of the
galactic bulge, with the monitoring of about 120000 stars in 12 windows
uniformly distributed in galactic latitude and longitude (Blanco & Terndrup,
1989 e Blanco, 1988) never before submitted to this kind of survey. For this
purpose, we have used the IAG/USP CCD Meridian Circle of the Abrah\~ao de
Moraes Observatory. The main objective of this work is the identification and
classification of variable objects. In this work we present the set up and
development of the necessary tools for a project like this and the posterior
analysis of our data. We briefly describe the construction of a program to
organize and detect variables among the observed stars, including real time
alerts (for variations greater than 0.3 magnitudes). The preliminary analysis
after the processing of 76 nights of observation yielded 479 variable stars,
from which 96.7 % of them are new. We discuss the preliminary classification of
this variables, based on: a) the observed amplitude of variation; b) the shape
of light curve; c) the expected variable classes among our data and d) the
calculated periods, whenever possible. Finally, we discuss the future
perspectives for the project and for the applications and analysis of the
discovered variable stars.Comment: 10 pages, 14 figures. Accepted by A&A
Análise citogenética de hÃbridos entre Triticum durum x Aegilops tauschii com potencial uso em programas de melhoramento genético de trigo.
Editores técnicos: Joseani Mesquita Antunes, Ana LÃdia Variani Bonato, Márcia Barrocas Moreira Pimentel
Cr(III) removal and recovery from Saccharomyces cerevisiae
Heavy metal recovery from biosorbents is of major importance in the assessment of competitiveness of biosorption processes. Several
desorption agents (H2SO4, HNO3, HCl, CH3COOH and EDTA) were tested for the selection of the optimal elution conditions for Cr(III)
recovery from Saccharomyces cerevisiae cells.
Sorption time was optimised as it plays an important role in the sorption–desorption process, being shown that a 30 min sorption period is
the best option to ensure metal removal from solution and good recovery from biosorbent. The optimal contact time with desorption agents
was also studied, as long exposures to these ones may cause cell damage, affecting biosorbent metal uptake capacity in subsequent sorption
cycles.
Each eluant was analysed in terms of its desorption capacity and its effect on the biomass metal uptake capacity in multiple
sorption–desorption cycles. Considering the effectiveness of chromium desorption from loaded biomass, it was possible to conclude that
H2SO4 (pH≈1) was the most effective eluant tested, accomplishing the highest Cr(III) recovery from S. cerevisiae in three consecutive
sorption/desorption cycles.
Regarding the damage caused by acid treatment on S. cerevisiae cells, assessed by the reduction on metal uptake capacity after elution,
it was possible to observe that sulphuric acid was the most harmful eluant causing long term negative effects in metal uptake. By the time
the experiments were interrupted (nearly 26 h of continuous cycles) biomass uptake capacity was reduced to about 77% of the value reached
before acid treatment.Fundação para a Ciência e a Tecnologia (FCT) – PRAXIS XXI/BD/15945/98
Sorption of Cr(III) from aqueous solutions by spent brewery grain
Two types of spent brewery grains were tested for Cr(III) uptake from aqueous solutions: not treated
spent grains (NTSG), obtained by abundant washing of spent grain obtained from a Portuguese
brewing industry with distilled water, and treated spent grain (TSG), prepared by treating NTSG with
NaOH 0.5 M for four hours followed by washing with distilled water.
Both materials were mixed with chromium solutions (50 and 100 mg Cr(III)/L), varying medium pH
from 3 to 5. Maximum metal uptake occurred at pH 5. Langmuir isotherm model well describes
Cr(III) biosorption by NTSG and TSG. The maximum uptake capacity obtained was 17.84 mg
Cr(III)/g NTSG and 13.87 mg Cr(III)/g TSG. Considering that Langmuir constant, b, reflecting the
affinity between the sorbent and the sorbate is lower for NTSG (0.0749 L/mg) it is possible to
conclude that the alkalis treatment does not improve spent grain uptake capacity for Cr(III).Fundação para a Ciência e a Tecnologia (FCT) - PRAXIS XXI/BD/15945/98
The pro-resolving lipid mediator Maresin 1 ameliorates pain responses and neuroinflammation in the spared nerve injury-induced neuropathic pain: A study in male and female mice
Specialized pro-resolving mediators (SPMs) have recently emerged as promising therapeutic approaches for neuropathic pain (NP). We evaluated the effects of oral treatment with the SPM Maresin 1 (MaR1) on behavioral pain responses and spinal neuroinflammation in male and female C57BL/6J mice with spared nerve injury (SNI)-induced NP. MaR1, or vehicle, was administered once daily, on post-surgical days 3 to 5, by voluntary oral intake. Sensory-discriminative and affective-motivational components of pain were evaluated with von Frey and place escape/avoidance paradigm (PEAP) tests, respectively. Spinal microglial and astrocytic activation were assessed by immunofluorescence, and the spinal concentration of cytokines IL-1 & beta;, IL-6, IL-10, and macrophage colony-stimulating factor (M-CSF) were evaluated by multiplex immunoassay. MaR1 treatment reduced SNI-induced mechanical hypersensitivity on days 7 and 11 in both male and female mice, and appeared to ameliorate the affective component of pain in males on day 11. No definitive conclusions could be drawn about the impact of MaR1 on the affective-motivational aspects of pain in female mice, since repeated suprathreshold mechanical stimulation of the affected paw in the dark compartment did not increase the preference of vehicle-treated SNI females for the light side, during the PEAP test session (a fundamental assumption for PAEP's validity). MaR1 treatment also reduced ipsilateral spinal microglial and astrocytic activation in both sexes and marginally increased M-CSF in males, while not affecting cytokines IL-1 & beta;, IL-6 and IL-10 in either sex. In summary, our study has shown that oral treatment with MaR1 (i) produces antinociception even in an already installed peripheral NP mouse model, and (ii) this antinociception may extend for several days beyond the treatment time-frame. These therapeutic effects are associated with attenuated microglial and astrocytic activation in both sexes, and possibly involve modulation of M-CSF action in males.& nbsp;This work was supported by University of Porto/Faculty of Medicine (https://sigarra.up.pt/fmup) and ESF - European Social Fund (https://ec. europa.eu/esf/home.jsp), through NORTE2020 - North Portugal Regional Operational Programme [NORTE-08-5369-FSE-000011-Doctoral Programmes - LTS' PhD fellowship], and by Fundacao Grunenthal Portugal (https://www. fundacaogrunenthal.pt), Bolsa Jovens Investigadores em Dor 2018 - LTS). The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript
Tuned liquid dampers simulation for earthquake response control of buildings
This paper is focused on the study of an earthquake protection system, the Tuned Liquid Damper (TLD), which
can, if adequately designed, reduce earthquake demands on buildings. This positive effect is accomplished taking
into account the oscillation of the free surface of a fluid inside a tank (sloshing). The behaviour of an isolated
Tuned Liquid Damper, subjected to a sinusoidal excitation at its base, with different displacement amplitudes,
was studied by finite element analysis. The efficiency of the TLD in improving the seismic response of an existing building, representative of modern architecture buildings in southern European countries was also evaluated based on linear dynamic analyses
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