Migration is the Driving Force of Rapid Aging in Puerto Rico: A Research Brief

2021 ◽  
Author(s):  
Amílcar Matos-Moreno ◽  
Alexis R. Santos-Lozada ◽  
Neil Mehta ◽  
Carlos F. Mendes de Leon ◽  
Félice Lê-Scherban ◽  
...  
Keyword(s):  
Puerto Rico ◽  
Driving Force

scholarly journals Innovation as Competitiveness Driving Force Through the Resources and Capacities of SMEs in Costa Rica, Puerto Rico, and Dominican Republic

2021 ◽  
Author(s):  
Ulises Mendez-Vega ◽  
Glenda Muñiz-Umana ◽  
José A, Flecha-Ortiz ◽  
Maria Santos-Corrada
Keyword(s):  
Puerto Rico ◽  
Costa Rica ◽  
Dominican Republic ◽  
Driving Force

Community evolution in Greater Antillean Anolis lizards: phylogenetic patterns and experimental tests

1995 ◽  
Vol 349 (1327) ◽  
pp. 69-75 ◽  
Keyword(s):  
Puerto Rico ◽  
Habitat Use ◽  
Adaptive Radiation ◽  
Driving Force ◽  
Phylogenetic Analyses ◽  
Experimental Tests ◽  
Small Islands ◽  
Ecological Interactions ◽  
Morphological Adaptation ◽  
Community Evolution

Phytogenies can be useful not only as a means of examining evolutionary hypotheses, but also as a source of hypotheses that can be tested using extant taxa. I illustrate this approach with examples from the study of community evolution in Caribbean Anolis lizards. Phylogenetic analyses indicate that not only are Anolis communities on Jamaica and Puerto Rico convergent in structure, but they have attained their similarity by evolving through a nearly identical sequence of ancestral communities. Examination of the pattern of community evolution suggests that interspecific competition is the driving force behind anole adaptive radiation. This hypothesis can be tested by investigating whether anoles shift their habitat use in the presence of competitors and, if so, whether such shifts lead to morphological adaptation to the new habitat. These hypotheses have been tested experimentally by introducing lizards onto small islands. Preliminary results indicate the existence of ecological interactions among sympatric anoles and that shifts in habitat use are accompanied by microevolutionary changes in morphology.

In situ TEM Studies of agglomeration of sub-nanometer Ru layers in Ru/C multilayers

1992 ◽  
Vol 50 (1) ◽  
pp. 256-257
Author(s):  
Tai D. Nguyen ◽  
Ronald Gronsky ◽  
Jeffrey B. Kortright
Keyword(s):  
Layered Structure ◽  
Driving Force ◽  
High Energy ◽  
Superior Performance ◽  
In Situ Tem ◽  
Rayleigh Instability ◽  
Practical Applications ◽  
Transmission Electron ◽  
Diffraction Patterns

Nanometer period Ru/C multilayers are one of the prime candidates for normal incident reflecting mirrors at wavelengths < 10 nm. Superior performance, which requires uniform layers and smooth interfaces, and high stability of the layered structure under thermal loadings are some of the demands in practical applications. Previous studies however show that the Ru layers in the 2 nm period Ru/C multilayer agglomerate upon moderate annealing, and the layered structure is no longer retained. This agglomeration and crystallization of the Ru layers upon annealing to form almost spherical crystallites is a result of the reduction of surface or interfacial energy from die amorphous high energy non-equilibrium state of the as-prepared sample dirough diffusive arrangements of the atoms. Proposed models for mechanism of thin film agglomeration include one analogous to Rayleigh instability, and grain boundary grooving in polycrystalline films. These models however are not necessarily appropriate to explain for the agglomeration in the sub-nanometer amorphous Ru layers in Ru/C multilayers. The Ru-C phase diagram shows a wide miscible gap, which indicates the preference of phase separation between these two materials and provides an additional driving force for agglomeration. In this paper, we study the evolution of the microstructures and layered structure via in-situ Transmission Electron Microscopy (TEM), and attempt to determine the order of occurence of agglomeration and crystallization in the Ru layers by observing the diffraction patterns.

The nucleation of cavities at grain boundaries

1987 ◽  
Vol 45 ◽  
pp. 288-291
Author(s):  
P. J. Goodhew
Keyword(s):  
Surface Tension ◽  
Surface Energy ◽  
Grain Boundaries ◽  
Radiation Damage ◽  
Impurity Concentration ◽  
Driving Force ◽  
Nucleation And Growth ◽  
Phase Boundaries ◽  
Cavity Nucleation ◽  
Spherical Bubble

Cavity nucleation and growth at grain and phase boundaries is of concern because it can lead to failure during creep and can lead to embrittlement as a result of radiation damage. Two major types of cavity are usually distinguished: The term bubble is applied to a cavity which contains gas at a pressure which is at least sufficient to support the surface tension (2g/r for a spherical bubble of radius r and surface energy g). The term void is generally applied to any cavity which contains less gas than this, but is not necessarily empty of gas. A void would therefore tend to shrink in the absence of any imposed driving force for growth, whereas a bubble would be stable or would tend to grow. It is widely considered that cavity nucleation always requires the presence of one or more gas atoms. However since it is extremely difficult to prepare experimental materials with a gas impurity concentration lower than their eventual cavity concentration there is little to be gained by debating this point.

Puerto Rico: A Cultural Crossroads

ASHA Leader ◽  
2008 ◽  
Vol 13 (15) ◽  
pp. 38-40
Author(s):  
Albert Villanueva-Reyes
Keyword(s):  
Puerto Rico

Rates of Cesarean Delivery Among Puerto Rican Women - Puerto Rico and the U.S. Mainland, 1992-2002

2006 ◽  
Author(s):  
R. Varela-Flores ◽  
◽  
H. Vázquez-Rivera ◽  
F. Menacker ◽  
Y. Ahmed ◽  
...  
Keyword(s):  
Puerto Rico ◽  
Puerto Rican ◽  
Cesarean Delivery ◽  
Puerto Rican Women ◽  
The U.S

Self-Help Strategies for Alzheimer Caregivers in Puerto Rico

2010 ◽  
Author(s):  
Carmelo Rodriguez-Perez ◽  
Sylvia Margarita Fernandez-Colorado ◽  
Jaime Veray
Keyword(s):  
Puerto Rico ◽  
Self Help
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