2,381 research outputs found
Cultivating Sustainable Coffee: Persistent Paradoxes
This chapter discusses the relationship and interconnections among changing the livelihoods of farmers, initiatives for sustainable coffee, and the production of shade-grown coffee. It examines the advantages and opportunities for farmers and producers engaged in coffee certification and diversification programs. The role of Fair Trade and organic networks in creating awareness of biodiversity conservation, the social and environment costs of coffee systems, and the need for supporting small farmers are also discussed. The methods to increase accountability and improve the efficiency of coffee cooperatives are presented in this chapter, as are the importance of understanding the sustainability initiatives and their implications for the regulators, along with the use of land patterns for coffee cultivation
The twilight zone in the parametric evolution of eigenstates: beyond perturbation theory and semiclassics
Considering a quantized chaotic system, we analyze the evolution of its
eigenstates as a result of varying a control parameter. As the induced
perturbation becomes larger, there is a crossover from a perturbative to a
non-perturbative regime, which is reflected in the structural changes of the
local density of states. For the first time the {\em full} scenario is explored
for a physical system: an Aharonov-Bohm cylindrical billiard. As we vary the
magnetic flux, we discover an intermediate twilight regime where perturbative
and semiclassical features co-exist. This is in contrast with the {\em simple}
crossover from a Lorentzian to a semicircle line-shape which is found in
random-matrix models.Comment: 4 pages, 4 figures, improved versio
On The Low Frequency Quasi Periodic Oscillations of X-ray Sources
Based on the interpretation of the twin kilohertz Quasi Periodic Oscillations
(kHz QPOs) of X-ray spectra of Low Mass X-Ray Binaries
(LMXBs) to the Keplerian and the periastron precession frequencies at the
magnetosphere-disk of X-ray neutron star (NS) respectively, we ascribe the low
frequency Quasi Periodic Oscillations (LFQPO) and HBO (15-60 Hz QPO for Z
sources or Atoll sources) to the periastron precession at some outer disk
radius.
The obtained conclusions include: all QPO frequencies increase with
increasing the accretion rate. The obtained theoretical relations between HBO
(LFQPO) frequency and the kHz QPO frequency are similar to the measured
empirical formula. Further, the possible dynamical mechanism for QPO production
is discussed.Comment: 6 pages, 2 figures, accepted by APSS, 200
Association between olfactory dysfunction and mood disturbances with objective and subjective cognitive deficits in long-COVID
Background and purposeThe coronavirus disease 2019 (COVID-19) has been associated with olfactory dysfunction. The persistent symptoms of anosmia or hyposmia were associated in previous studies with the development of memory impairment and mood disturbances. We aimed to investigate the association between the chronicity of reported olfactory dysfunction and subjective and objective cognitive performance in long-COVID patients and to explore whether their emotional symptoms are related to their cognition.MethodsOne hundred twenty-eight long-COVID participants were recruited. Reported symptomatology, subjective memory complaints, anxiety and depression symptomatology, and trait-anxiety were assessed. Subjective memory complaints and mood disturbances were compared among groups of participants with olfactory dysfunction as an acute (AOD), persistent (POD), or nonexistent (NOD) symptom. Seventy-six of the volunteers also participated in a face-to-face session to assess their objective performance on tests of general cognitive function and verbal declarative memory. Objective cognitive performance and mood disturbances were compared among the AOD, POD, and NOD groups.ResultsThe subjective memory complaints and the anxiety and depression symptoms were similar among the groups, but the score in general cognitive function was lower in the participants with symptoms of acute olfactory dysfunction than in those with no olfactory symptoms at any time. Participants’ memory complaints were positively related to their emotional symptoms. The relationship between depressive symptomatology and memory complaints interacted with the olfactory dysfunction, as it only occurred in the participants without symptoms of olfactory dysfunction. Depressive symptomatology and acute olfactory symptoms were negatively associated with general cognitive function and delayed memory performance. The months elapsed from diagnosis to assessment also predicted delayed memory performance. Anxious symptomatology was negatively associated with the immediate ability to recall verbal information in participants who did not present olfactory dysfunction in the acute phase of the infection.ConclusionOlfactory dysfunction in the acute phase of the infection by COVID-19 is related to cognitive deficits in objective tests, and mood disturbances are associated with self-reported and objective memory. These findings may contribute to further understanding the neuropsychological and emotional aspects of long-COVID
Free Form of the Foldy-Wouthuysen Transformation in External Electromagnetic Fields
We derive the exact Foldy-Wouthuysen transformation for Dirac fermions in a
time independent external electromagnetic field in the basis of the Ritus
eigenfunctions, namely the eigenfunctions of the operator , with . In this basis, the transformation
acquires a free form involving the dynamical quantum numbers induced by the
field.Comment: 8 pages. Accepted in J. Phys. A: Math. and Theo. (Fast Track
Communication
Componentes minoritarios de aceites obtenidos de frutos de palmeras de la región amazónica
This study deals with the characterization of minor compounds in oils obtained from the mesocarp of fruits of the main palm species from the State of Amapá, Brazil, i.e. bacaba (Oenocarpus bacaba), buriti (Mauritia flexuosa), inajá (Maximiliana maripa), pupunha (Bactris gasipaes) and tucumã (Astrocaryum vulgare). The concentration of minor glyceridic compounds, i.e. dimeric triacylglycerols (TAG), the oxidized TAG and diacylglycerols (DAG) related to oil quality, and the compounds of unsaponifiable matter, i.e. hydrocarbons, aliphatic alcohols, sterols and tocopherols have been determined.
The results indicate that the extracted oils had good initial quality, with DAG as the major glyceridic compound. The contents of hydrocarbons (50-734 mg·kg–1) and aliphatic alcohols (80-490 mg·kg–1) were highly variable with inajá oil containing the highest contents. In the case of tocopherols, buriti (1567 mg·kg–1) and tucumã (483 mg·kg–1) oils had the highest contents and the presence of significant amounts of tocotrienols was only detected in inajá oil. Finally, high concentrations of sterols were found in all the samples, particularly in the oils from pupunha (4456 mg·kg–1) and tucumã (2708 mg·kg–1), with β-sitosterol being the major sterol in all the samples with percentages between 65 and 83%.El objetivo de este estudio fue la caracterización de los componentes menores presentes en los aceites obtenidos del mesocarpio de frutos de especies de bacaba (Oenocarpus bacaba), buriti (Mauritia flexuosa), inajá (Maximiliana maripa), pupuña (Bactris gasipaes) y tucumá (Astrocaryum vulgare), de importante producción en el Estado de Amapá, Brasil.
Se determinaron las dos principales fracciones presentes en los aceites. Por una parte, los compuestos menores derivados de los componentes mayoritarios o triglicéridos (TAG): dímeros de TAG, TAG oxidados y diglicéridos (DAG) relacionados con la calidad de los aceites y, por otra, los principales grupos presentes en la fracción insaponificable (hidrocarburos, alcoholes alifáticos, esteroles y tocoferoles) relacionados con la calidad de los aceites.
Los resultados indicaron que todos los aceites extraídos tenían buena calidad inicial, siendo los DAG los mayoritarios entre los compuestos menores glicerídicos. La concentración de hidrocarburos (50-734 mg·kg–1) y de alcoholes alifáticos (80-490 mg·kg–1) fue muy variable correspondiendo al aceite de inajá el mayor contenido en hidrocarburos y en alcoholes. En el caso de los tocoferoles, las mayores cantidades correspondieron a los aceites de buriti (1567 mg·kg–1) y tucumá (483 mg·kg–1) y la presencia de cantidades significativas de tocotrienoles sólo se detectaron en aceite de inajá. Finalmente, se encontraron concentraciones elevadas de esteroles en todas las muestras, especialmente en los aceites de pupuña (4456 mg·kg–1) y tucumá (2708 mg·kg–1), siendo el β-sitosterol el esterol mayoritario con porcentajes entre 65 y 83%
Food security and smallholder coffee production: current issues and future directions
In recent years, there has been growing discussion within the specialty coffee industry about the preva- lence of seasonal food insecurity in coffee growing communities. The idea that coffee producers lack re- sources to feed themselves and their families flies in the face of Fair Trade and other sustainable coffee ini- tiatives, which were designed to ensure a viable livelihood and improved conditions for small-scale coffee farmers around the world. Though these certifications represent an important step toward delivering better prices to farmers, they are inadequate tools to stand alone against the formidable and entrenched barriers faced by this population. Small-scale farmers are esti- mated to produce 70% of the world\u27s coffee supply (Eakin et al, 2009), within an industry supported by up to 25 million coffee producers. If you also include coffee harvesters, processors, and industry workers, the total is closer to 100 million people whose livelihoods depend on the crop in some way (Jha et al, 2011)
The Landau problem and noncommutative quantum mechanics
The conditions under which noncommutative quantum mechanics and the Landau
problem are equivalent theories is explored. If the potential in noncommutative
quantum mechanics is chosen as with defined in the
text, then for the value (that
measures the noncommutative effects of the space), the Landau problem and
noncommutative quantum mechanics are equivalent theories in the lowest Landau
level. For other systems one can find differents values for
and, therefore, the possible bounds for should be searched in
a physical independent scenario. This last fact could explain the differents
bounds for found in the literature.Comment: This a rewritten and corrected version of our previous preprint
hep-th/010517
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