971 research outputs found
Distribution Patterns of Great Basin Conifers: Implications of Extinction and Immigration
Factors influencing the distribution of scattered montane conifers on mountaintops in the Great Basin of North America were investigated. The sources of data were collections and observations on more than 300 mountain ranges in the region. All mountains in the region with at least one montane conifer species and all adjacent source areas were included in the data set. In all, 164 montane island sites and 40 mainland sites were used in the analyses. Physical data for each site were compiled and regression analyses were conducted to test the predictions of three island biogeography models: immigration, extinction, and equilibrium. These models were treated as alternatives to the Random Placement Hypothesis. The Random Placement Hypothesis was refuted. However, none of the island biogeography models explained the observed patterns because mainland species–area slopes were within the expected range of island slopes. The pattern that emerges is one in which both the mainlands and islands represent the remnants of a preexisting regional conifer flora. The vertical relief of a site’s montane zone is a better estimate of habitat diversity than area, and explains 65% of all variation in species richness on mountain ranges in the region. Although not all predictions of the island biogeography models were supported, it appears that both immigration and extinction of montane and subalpine conifers have occurred in the region during the Late Quaternary. Extinction was more important than immigration in shaping modern conifer distributions because area, not distance to sources, has a stronger influence on species richness
Clasificación textural del cuarzo epitermal (Au-Ag) de relleno filoniano del área volcánica de Cabo de Gata, Almería
El estudio de filones epitermales, particularmente del tipo low-sulphidation o adularia-sericita, pone de manifiesto la existencia, en el relleno hidrotermal, de frecuentes manifestaciones de cuarzo anómalo, por sus texturas y características petrográficaso La interpretación de estos tipos de cuarzo plantea problemas a la hora de establecer su origen y para cualquier estudio de inclusiones fluidas, al obligar a cuestionar el carácter primario de asociaciones de inclusiones que en otras condiciones sería indudable (por ejemplo, las asociadas a zonado de crecimiento). El campo filoniano de Cabo de Gata (Almería) ofrece un amplio muestrario de este tipo de manifestaciones de cuarzo epitermal, el cual ha servido de base para proponer una clasificación de dichas texturas, como primer paso para abordar, con el rigor y precisión debidos, ulteriores estudios mineralógicos, geoquímicos y, en particular, microtermométricos por inclusiones fluidas. Se recogen de la literatura internacional y se aplican las ideas derivadas de otros campos similares y se propone una clasificación -Cuadros 1 y 2- que distingue las generaciones de cuarzo estrictamente primario (es decir, no transformadas por procesos ulteriores) y las modificadas, recristalizadas, secundarias, etc... Todas ellas se documentan gráficamente. Las texturas recristalizadas son particularmente engañosas, ya que pueden mostrar rasgos aparentemente primarios, como zonado de crecimiento, que inducen a error al interpretar las inclusiones correspondientes como primarias. Dicha clasificación tiene por objeto no sólo el asegurar el rigor necesario para abordar la petrografía de inclusiones fluidas, sino también el apoyo a la exploración y a la caracterización tipológica de las concentraciones de metales preciosos. Se aportan criterios para facilitar la interpretación y reconocimiento de procesos epitermales en general y, particularmente, mediante la caracterización de las texturas de relleno en campo y laboratorio, para distinguir ambientes epitermales de otros (vbgr. metamórficos, mesotermales o ligados a zonas de cizalla), relevantes o no para la exploración. Se ha hecho el esfuerzo de referir las texturas a términos castellanos, evitando la repetición "ad infinitum", no siempre necesaria, de términos anglosajones. Lo que en algunos casos obliga a innovar, pero, para evitar toda confusión, se ha reducido al mínimo indispensable la terminología nueva. Para mayor precisión y para facilitar la comparación con otros trabajos, se propone -Cuadro 3- una tabla de equivalencias entre la terminología (española) empleada y definida en este trabajo y la más extendida en la literatura internacional (inglés, francés)
A Study to Assess the Effectiveness of Planned Teaching Programme on Knowledge regarding Human Rights of Mentally Ill among College Students in Sakthi College of Arts and Science for women at Oddanchatram
A study was conducted "to assess the effectiveness of ‘planned teaching programme’ on improving the knowledge regarding rights of mentally ill among college students in Sakthi College of arts and science at Oddanchatram
The objectives of the study were,
• To assess the pre – test level of knowledge regarding rights of mentally ill among college students in Sakthi College of arts and science at Oddanchatram.
• To compare the pre – test and post - test level of knowledge regarding rights of mentally ill among college students in Sakthi College of arts and science at Oddanchatram.
• To assess the effectiveness of ‘planned teaching programme’ on improving the knowledge regarding rights of mentally ill among college students in Sakthi College of arts and science at Oddanchatram.
• To find out the association between pre-test level of knowledge regarding rights of mentally ill among college students with selected demographic variables in Sakthi College of arts and science at Oddanchatram. The research design was adopted for this study is a Quasi –experimental design (One group pre-test post-test design). [The study adopted pre test, intervention and post test].
The conceptual frame work was based on King’s goal attainment theory. It consists of concepts that are communication-perception-reaction, and communication transaction-feedback.
In this study the researcher administers planned teaching programme on knowledge regarding rights of mentally ill among college students in Sakthi College of arts and science at Oddanchatram.
The basis assumption of the theory is the college students has to improve the knowledge regarding rights of mentally ill and finally validating that the need for help was met.
The sample size consists of 30 students those who are studied in second year B.Sc (Physics) at Sakthi College of arts and science for women at Oddanchatram. Pre test data was collected by researcher using modified questionnaires on 1st day.
College students received intervention of ‘Planned teaching programme regarding rights of mentally ill’ on 2nd day. Post test was conducted by the researcher for using the same questionnaires on the 3rd day.
The Finding shows that, among 30 samples, 27 (73.33%) samples belonged to the Age Group 18 years, whereas only 1 (73.3%) of the sample belonged to the age group of 20 years and above.
Regarding Religion majority15 (50%) samples belonged to the Hindu Religion, whereas only 3 (10%) of the samples belonged to the Muslim religion.
Regarding Educational Status of the parents, majority 9(30%).of the samples belongs to the undergraduate degree and 6 (20%) of the samples belongs to post graduate.
Regarding to the parents occupation majority is12 (40%) of the samples belongs to the private employee and 4 (13.3%) of the samples belongs to unemployed.
Regarding any medical professionals majority 27 (90%) of the samples are say “No” and 3 (10%) of them says “Yes”.
Regarding any mental ill patients in her family, 26 (86.7%).of the samples say “No” and 4 (13.3%) says “Yes”.
Regarding Previous knowledge about rights mentally ill patients, 25 (83.3%) samples say that, “No” and 5 (16.6%) of them says that, “Yes”.
The findings shows that in pre test scores on the level of Level of Knowledge 17 (56.67%) of them had No Knowledge, 9 (30%) of them had Low Knowledge, and 4 (13.33%) of them had Moderate Knowledge respectively.
Whereas post test scores on the level of Level of Knowledge 3 (10%) of them had Low Knowledge, 9(30%) of them had Moderate Knowledge and 18 (60%) of them had High Knowledge respectively.
This finding reveals that, after the planned teaching programme the level of knowledge regarding rights of mentally ill among college students were improved in post test than pre test.
The finding shows that the pre test calculated value was 2.1 and the tablatde ’t’ value is 1.699, which was significant at P< 0.05.
Hence H1 is accepted. It can be concluded that ‘planned teaching programme was effective in improving the knowledge level among college students.
The finding shows that, there was statistically significant association between the level of knowledge regarding rights of mentally ill among college students and their demographic variables like parents occupation, medical professionals in their family, mentally ill patients in their family and previous knowledge regarding rights of mentally ill.
And the findings shows that, there was not statistically significant association between the level of knowledge regarding rights of mentally ill among college students and their demographic variables like age group, religion, and educational status of the parents and presents of mentally ill patients in their family
Inversion of the Diffraction Pattern from an Inhomogeneously Strained Crystal using an Iterative Algorithm
The displacement field in highly non uniformly strained crystals is obtained
by addition of constraints to an iterative phase retrieval algorithm. These
constraints include direct space density uniformity and also constraints to the
sign and derivatives of the different components of the displacement field.
This algorithm is applied to an experimental reciprocal space map measured
using high resolution X-ray diffraction from an array of silicon lines and the
obtained component of the displacement field is in very good agreement with the
one calculated using a finite element model.Comment: 5 pages, 4 figure
Hydration of Na+, Ni2+, and Sm3+ in the Interlayer of Hectorite: A Quasielastic Neutron Scattering Study
International audienceQuasielastic neutron scattering experiments were performed with Na−hectorite, Ni−hectorite, and Sm−hectorite samples in order to find out whether Sm3+ is present in the clay interlayer as a fully hydrated cation (outer-sphere complex), or, as it follows from neutron diffraction data analysis, it is dehydrated and bound to the clay surface (inner-sphere complex). The results obtained for the Sm−hectorite were compared with other interlayer cations: strongly hydrated Ni2+ and relatively weakly hydrated Na+. It was found that water mobility in the Sm−hectorite sample is very close to the water mobility in Ni−hectorite. This is only possible if the Sm3+ ion is fully hydrated. It was shown that water molecules hydrating Ni2+ and Sm3+ exhibit diffusion mobility measurable with backscattering spectrometers. The diffusion coefficients of the exchangeable cations were found using the slow exchange approximations DNi = (0.05 − 0.14) × 10−9 m2/s and DSm = (0.04 − 0.18) × 10−9 m2/s
Synthesis of a Se0/Calcite Composite Using Hydrothermal Carbonation of Ca(OH)2 Coupled to a Complex Selenocystine Fragmentation
International audienceElemental selenium (Se0)/calcite composites were synthesized in a batch system by hydrothermal carbonation of calcium hydroxide under high CO2−Ar pressure (90 bar) and high temperature (90 °C) coupled to a complex selenocystine fragmentation. Under O2-poor conditions, the composite consisted predominantly of spherical, amorphous nanoparticles of elemental red selenium (<500 nm) deposited on the calcite matrix. Conversely, under O2-rich conditions, the composite consisted rod-shaped, well-crystallized microparticles of elemental gray selenium (<25 µm) dispersed in the calcite matrix. The carbonate matrix was constituted by nano- to microrhombohedral crystals (<2 µm) and micrometric agglomerates and/or aggregates (<5 µm). Our results present a new synthesis path to Se0/calcite composites, with spherical or rod-shaped Se0 morphology with high potential for medical (e.g., dietary supplement) or industrial (e.g., pigments) applications. Furthermore, this study may have implications in the field of biomineralization
Arsenite sorption and co-precipitation with calcite
Sorption of As(III) by calcite was investigated as a function of As(III)
concentration, time and pH. The sorption isotherm, i.e. the log As(III) vs. log
[As(OH)3 degrees / Assat] plot is S-shaped and has been modelled on an extended
version of the surface precipitation model. At low concentrations, As(OH)3
degrees is adsorbed by complexation to surface Ca surface sites, as previously
described by the X-ray standing wave technique. The inflexion point of the
isotherm, where As(OH)3 degrees is limited by the amount of surface sites (ST),
yields 6 sites nm-2 in good agreement with crystallographic data. Beyond this
value, the amount of sorbed arsenic increases linearly with solution
concentration, up to the saturation of arsenic with respect to the
precipitation of CaHAsO3(s). The solid solutions formed in this concentration
range were examined by X-ray and neutron diffraction. The doped calcite lattice
parameters increase with arsenic content while c/a ratio remains constant. Our
results made on bulk calcite on the atomic displacement of As atoms along
[0001] direction extend those published by Cheng et al., (1999) on calcite
surface. This study provides a molecular-level explanation for why As(III) is
trapped by calcite in industrial treatments.Comment: 9 page
L'ocytocine, peptide aux multiples facettes
Accouchement, naissance, attachement parents-enfant :
quiconque s’y intéresse a entendu parler de cette molécule
à tout faire, l’ocytocine, surnommée hormone de l’amour.
Invitation est faite à découvrir ce petit peptide
The radon anomaly of Porcheresse (Ardennes, Belgium). A case study
From a very high radon concentration in a dwelling of the village of Porcheresse, one discusses on of the significance of the numerous radon indoor anomalies detected in the southern part of Belgium
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