9,916 research outputs found
Recovery of flavonoids from three-phase olive pomace by aqueous ethanol extraction
A three-phase olive pomace (OP), the solid by-product originating from the production of olive oil, was investigated as a potential source of flavonoids. Flavonoids were extracted by an environmentally friendly procedure using aqueous ethanol as solvent. The flavonoid content of OP, expressed as quercetin equivalents (QE) per unit weight of dry material, was 25.28 ± 0.93 mg QE/g. To evaluate the effects of temperature (T), extraction time (E), liquid-to-solid ratio (R) and solvent composition (C) on the yield of flavonoid extraction (y), a Central Composite Design (CCD) coupled with Response Surface Methodology (RSM) was used. Statistical analysis of the results showed that T was the most influential factor, followed by E, R and C. A reduced polynomial model was developed by the stepwise regression method which provided an accurate description of the extraction process. Maximization of the response variable gave: ymax = 90.5% at T = 69.9 °C, E = 212 min, R = 36.7 mL/g and C = 43.7%. Overall, the obtained results support the use of three-phase OP as a source of flavonoids and give useful indications on the influence of process variables on their recovery
The Role of Mass and Environment in Multiple Star Formation: A 2MASS Survey of Wide Multiplicity in Three Young Associations
We present the results of a search for wide binary systems among 783 members
of three nearby young associations: Taurus-Auriga, Chamaeleon I, and two
subgroups of Upper Scorpius. Near-infrared (JHK) imagery from 2MASS was
analyzed to search for wide (1-30"; ~150-4500 AU) companions to known
association members, using color-magnitude cuts to reject likely background
stars. We identify a total of 131 candidate binary companions with colors
consistent with physical association, of which 39 have not been identified
previously in the literature. Our results suggest that the wide binary
frequency is a function of both mass and environment, with significantly higher
frequencies among high-mass stars than lower-mass stars and in the T
associations than in the OB association. We discuss the implications for wide
binary formation and conclude that the environmental dependence is not a direct
result of stellar density or total association mass, but instead might depend
on another environmental parameter like the gas temperature. We also analyze
the mass ratio distribution as a function of mass and find that it agrees with
the distribution for field stars to within the statistical uncertainties. The
binary populations in these associations generally follow the empirical
mass-maximum separation relation observed for field binaries, but we have found
one candidate low-mass system (USco-160611.9-193532; Mtot~0.4 Msun) which has a
projected separation (10.8"; 1550 AU) much larger than the suggested limit for
its mass. (Abridged)Comment: Accepted to ApJ; 27 pages in emulateapj format. The full version of
table 2 can be downloaded via http://www.astro.caltech.edu/~alk/tab2.pdf
(PDF) or http://www.astro.caltech.edu/~alk/tab2.txt (text
New eigenvalue estimates involving Bessel functions
Given a compact Riemannian manifold (Mn, g) with boundary ∂M, we give an estimate for the quotient R ∂M f dµg R M f dµg , where f is a smooth positive function defined on M that satisfies some inequality involving the scalar Laplacian. By the mean value lemma established in [39], we provide a differential inequality for f which, under some curvature assumptions, can be interpreted in terms of Bessel functions. As an application of our main result, a new inequality is given for Dirichlet and Robin Laplacian. Also, a new estimate is established for the eigenvalues of the Dirac operator that involves a positive root of Bessel function besides the scalar curvature. Indepen[1]dently, we extend the Robin Laplacian on functions to differential forms. We prove that this natural extension defines a self-adjoint and elliptic operator whose spectrum is discrete and consists of positive real eigenvalues. In particular, we characterize its first eigenvalue and provide a lower bound of it in terms of Bessel functions
Study of Rheological, Chemical, and Microbiological Properties of Chami, A Traditional Emirati Soft Chees
In this work, ten Emirati Chami cheese samples were collected and analyzed to determine their chemical composition, texture, rheology, and microbiological properties. Chami cheeses showed large variations in moisture (60.9–84.1%), protein (7.5–14.6%), fat (0.5–7.8%), and ash (3.4–8.0%) contents as well as in pH (3.6–4.4), and water activity (0.977–0.999%). The variation in fat content of samples suggested that extra fat was added; this added fat was either butter or vegetable oil as indicated by the fatty acid composition. The different samples showed peaks of variable size for fat melting. The sodium content in the 10 cheese samples varied from 223–2410 mg/kg, with three samples showing very high contents of 1756, 2024, and 2410 mg/kg, indicating added salt. The sample with the lowest moisture content (60.9%) had the hardest texture among the cheeses. Rheological examination showed that Chami cheese samples were more elastic than they were viscous. Seven Chami samples contained lactic acid bacteria (6.5–9.1 log CFU/mL), while 5 samples showed yeast and mold growth (5.3–8 log CFU/mL). Six Chami samples showed the presence of Staphylococcus spp., while coliform bacteria were detected in 4 samples. All samples tested positive for Salmonella and 4 were positive for Listeri
Clinical Characteristics and Outcomes Among Individuals With Spinal Implant Infections: A Descriptive Study.
Little is known about the clinical presentation and outcomes associated with spinal implant infections. Here, we describe a single center's experience in a retrospective cohort of 109 individuals with spinal implant infections, including clinical, microbiological, therapeutic, and outcome data
A SHRM Perspective on International Compensation and Reward Systems
We re-examine the efficacy of the SHRM perspective from the vantage point of a specific HRM system, international compensation and rewards, to gain new insights into existing conceptual models. Looking at SHRM from the ground up suggests that, to continue informing our understanding of the HRM-organizational effectiveness (OE) relationship, research will need to adopt richer theory and measures of specific HRM systems and extrapolate important contextual factors that influence relationships between OE and specific HRM systems
A Simultaneous Determination of the Inter Vivos Transfer and the Unemployment Duration: the Malian case
This article aims to establish a link between the unemployment duration and the inter vivos transfers received by the unemployed individuals. We present a model where the transfer shapes the receiver's job search strategy while the donor bases it on the receiver's unemployment duration. Ultimately, a recursion arises and leads to a simulteanous determination of the transfer and the duration. The model aims to apprehend the job search behaviour in a context where the unemployment compensation system is weak or absent, like in some developing countries. We will take Mali as a study case.unemployment; inter-vivos transfer; job search; household economics.
Probabilistic Modeling Paradigms for Audio Source Separation
This is the author's final version of the article, first published as E. Vincent, M. G. Jafari, S. A. Abdallah, M. D. Plumbley, M. E. Davies. Probabilistic Modeling Paradigms for Audio Source Separation. In W. Wang (Ed), Machine Audition: Principles, Algorithms and Systems. Chapter 7, pp. 162-185. IGI Global, 2011. ISBN 978-1-61520-919-4. DOI: 10.4018/978-1-61520-919-4.ch007file: VincentJafariAbdallahPD11-probabilistic.pdf:v\VincentJafariAbdallahPD11-probabilistic.pdf:PDF owner: markp timestamp: 2011.02.04file: VincentJafariAbdallahPD11-probabilistic.pdf:v\VincentJafariAbdallahPD11-probabilistic.pdf:PDF owner: markp timestamp: 2011.02.04Most sound scenes result from the superposition of several sources, which can be separately perceived and analyzed by human listeners. Source separation aims to provide machine listeners with similar skills by extracting the sounds of individual sources from a given scene. Existing separation systems operate either by emulating the human auditory system or by inferring the parameters of probabilistic sound models. In this chapter, the authors focus on the latter approach and provide a joint overview of established and recent models, including independent component analysis, local time-frequency models and spectral template-based models. They show that most models are instances of one of the following two general paradigms: linear modeling or variance modeling. They compare the merits of either paradigm and report objective performance figures. They also,conclude by discussing promising combinations of probabilistic priors and inference algorithms that could form the basis of future state-of-the-art systems
Assessing the impacts of drought on UK wheat production
Water limitations typically reduce UK wheat yields on average by 1-2 t ha-
1
,
although this can be considerably more in extreme drought years. With the
frequency and intensity of droughts expected to increase under a changing
climate, an improved understanding of the impacts of drought and better systems
for agricultural drought monitoring are required. Previous studies, however, have
found no significant relationship between UK wheat yields and commonly
employed drought severity indices (DSI). Using historical (1911-2015) daily
weather data for Cambridge the Standardized Precipitation Index (SPI), the
Standardized Precipitation and Evapotranspiration Index (SPEI), the Palmer
Drought Severity Index (PDSI) and the Potential Soil Moisture Deficit (PSMD)
were calculated on various time steps (e.g. 1-12 months for SPI and SPEI) to
provide a drought record for the site. A wheat crop growth simulation model
(Sirius) was then used to simulate the effects of the identified historic droughts
on wheat yields. The use of the Sirius crop model removed the non-drought
related yield losses (e.g. disease, pests, and lodging) present in national yield
records. Using the Spearman’s Rho correlation coefficient (r) the simulated yield
record was then correlated against the different DSIs. The droughts of 1921, 1976
and 2010 were found to be the most extreme in term of yield reduction. In
addition, there were also two noticeable periods of successive yield loss in the
early 1940s and between 2009 and 2013. All DSIs showed significant (p = 0.05)
correlations on monthly time steps between April and August. The SPI, SPEI and
PSMD showed a strong correlation to wheat yields (r = 0.64 to 0.66) on time steps
incorporating the end of the ‘construction’ and the entirety of the ‘production’
phases for wheat growth. The PDSI showed the weakest correlation (r = 0.55),
although it may be helpful in identifying yield-limiting droughts earlier in the year.
The research has contributed new scientific insights and understanding of the
impacts of historic droughts on wheat productivity, and demonstrated the
application of DSIs in monitoring potentially yield-limiting droughts. The research
also provides new evidence to support developments in UK food security and
drought management for agriculture
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