scholarly journals Evidence of Correlation between High Frequency Geomagnetic Variations and Seismicity in the Caribbean

2021 ◽  
Vol 10 (02) ◽  
pp. 30-41
Author(s):  
Bladimir Moreno ◽  
Eric Calais
Keyword(s):  
High Frequency ◽  
Geomagnetic Variations ◽  
The Caribbean

scholarly journals Calculation of the Specific Attenuation in Satellite Bands Due to the Rain in the City of Cartagena and its Importance in the Naval Field

2020 ◽  
Vol 14 (27) ◽  
pp. 39-53
Author(s):  
Lorenzo Cardona ◽  
William Cuadrado
Keyword(s):  
High Frequency ◽  
Information Exchange ◽  
Communication Systems ◽  
Information Sources ◽  
Caribbean Region ◽  
Frequency Bands ◽  
Specific Attenuation ◽  
The Caribbean ◽  
The City

This work studies the attenuation by rain that occurs in the Caribbean region, specifically, in high frequency bands, considering that modern communication systems make greater use of satellite bands. In this sense, the methodology of the recommendation ITU 838 was used to calculate the radio attenuation by rain in the city of Cartagena (Colombia), for the range of 1-100 GHz, and the data provided by the Center of Oceanographic and Hydrographic Research - CIOH were used as atmospheric information sources. As a result, the attenuation for the first quarter of the analyzed years was observed to be low (2.0x10-2 dB/km), growing in the following months until October (1.0x10-1 dB/km), when it decreases again. This information is particularly useful in the naval field, especially, in relation to the use of these frequencies for information exchange.

The coding of perfect meaning in African, Asian and Caribbean Englishes

2017 ◽  
Vol 23 (3) ◽  
pp. 509-529
Author(s):  
CRISTINA SUÁREZ-GÓMEZ
Keyword(s):  
High Frequency ◽  
American English ◽  
World Englishes ◽  
Evolutionary Stage ◽  
Outer Circle ◽  
Text Type ◽  
The Caribbean ◽  
The One

The perfect in World Englishes has attracted much attention recently, especially from a semasiological perspective, in which the analytic have + participle is analysed in comparison with the synthetic preterite. This article intends to achieve a more holistic picture of the expression of perfect meaning in World Englishes, which allows us to identify how perfect meaning is expressed in all pragmatic contexts. In this study, all the occurrences of ten high-frequency verbs are examined in order to single out those expressing perfect meaning. The corpus (8.8m words in total) includes ten components of the International Corpus of English: eight Outer Circle varieties from Africa, Asia and the Caribbean, and two reference varieties: British and American English. The relevant examples are tabulated across variables such as presence of adverbials, type of perfect meaning, lexical verb, mode, text type and evolutionary stage. The results show that the envelope of variation is much wider than the one traditionally acknowledged in current grammars of English, and that type of meaning, lexical verb or text type are crucial determiners in the choice of particular forms to express perfect meaning. By contrast, mode or evolutionary stage does not seem to have a bearing on the differences between varieties.

ADORNMENT AND IDENTITY

1999 ◽  
Vol 10 (1) ◽  
pp. 117-127 ◽  
Author(s):  
Ilean Isel Isaza Aizpurúa ◽  
Patricia A. McAnany
Keyword(s):  
High Frequency ◽  
Social Identities ◽  
Freshwater Species ◽  
Late Formative ◽  
The Caribbean ◽  
Shell Beads ◽  
Maya Site ◽  
Middle Formative ◽  
Early Late ◽  
Insight Into

Excavations in Formative and Early Classic contexts at the Maya site of K'axob have produced a sample of 2,568 worked-shell ornaments crafted from both marine and freshwater species. Predominantly shell beads, the sample also includes unique pendants, figurines, and tinklers. A high frequency of unfinished beads in Middle Formative and early Late Formative midden contexts provides strong evidence of localized shell working and trading connections with the Caribbean. Personal adornment crafted from shell is an important item in many burials, including those of children. The most lavish disposal of shell, however, occurs in one of the earliest Middle Formative interments at K'axob. An adult male—who may have been a “founder” of K'axob—was buried with 2,019 shell beads. Through time, fewer individuals were buried with worked shell as the intricacy of shell working became more elaborate and possibly iconic of roles of authority. Interpretation of archaeological patterns indicates that shell beads can provide significant insight into the construction of social identities.

scholarly journals Ectoparasites of dogs in home environments on the Caribbean slope of Costa Rica

2012 ◽  
Vol 21 (2) ◽  
pp. 179-183 ◽  
Author(s):  
Adriana Troyo ◽  
Ólger Calderón-Arguedas ◽  
Gilbert Alvarado ◽  
Luis E. Vargas-Castro ◽  
Adrián Avendaño
Keyword(s):  
Costa Rica ◽  
Home Environment ◽  
High Frequency ◽  
Relative Frequency ◽  
Rhipicephalus Sanguineus ◽  
Boophilus Microplus ◽  
Home Environments ◽  
The Caribbean ◽  
Study Sites ◽  
Common Combination

Reports on ectoparasites on dogs in Central America are scarce. The aim of this study was to identify flea, louse and tick species infesting dogs in home environments on the Caribbean slope of Costa Rica, and determine their frequency and coexistence. Ectoparasites were collected from dogs in 83 rural homes at five study sites. Specimens were identified and separated according to species. Fleas were the most common ectoparasite (G = 22,217, DF = 8, p = 0.004). Ctenocephalides felis and Pulex simulans were found in 83% and 55% of the homes with ectoparasites, respectively. Trichodectes canis (13%), Heterodoxus spiniger (10%), Rhipicephalus sanguineus (18%), Rhipicephalus (Boophilus) microplus (5%) and Amblyomma ovale (8%) were also present. More than one species was collected in most cases (66%), and the most common combination was C. felis and P. simulans (59% of homes with fleas). The high frequency of P. simulans emphasizes the need for adequate identification. This was the first study involving different ectoparasites of dogs in Costa Rica, as well as the first report of T. canis in this country. The relative frequency and coexistence of these ectoparasites in the home environment may have implications for animal and human health.

scholarly journals An Analysis of Low- and High-Frequency Summer Climate Variability around the Caribbean Antilles

2012 ◽  
Vol 25 (11) ◽  
pp. 3942-3952 ◽  
Author(s):  
Isabelle Gouirand ◽  
Mark R. Jury ◽  
Bernd Sing
Keyword(s):  
Climate Variability ◽  
North Atlantic ◽  
High Frequency ◽  
Low Frequency ◽  
Late Summer ◽  
Summer Climate ◽  
The North ◽  
Tropical North Atlantic ◽  
Low Pass ◽  
The Caribbean

This study contrasts the pattern of low-frequency (LF) and high-frequency (HF) climate variability in the eastern Caribbean. A low-pass Butterworth filter is used to study oscillations in rainfall and regional SST on time scales of greater and less than 8 yr in the period 1901–2002. The results show that the southern and northern Antilles are dominated by HF variability, whereas rainfall fluctuations in the eastern Antilles oscillate at quasi-decadal periods over the 102-yr record. In the southern Antilles, the HF rainfall signal derives from a late-summer response to the ENSO phase: warm and dry versus cool and wet. In the northern Antilles, the HF signal relates to a combination of an ENSO and North Atlantic Oscillation (NAO) phase: a warm ENSO and a negative NAO bring wetter conditions, while a cool ENSO and a positive NAO bring drier conditions. The early rainfall LF signal in SST is characterized by a dipole between the North Atlantic and South Atlantic and is associated with cross-equatorial winds that promote convection in the Caribbean. The study analyzes the upper-ocean structure—in particular, a low (high) salinity signal in the tropical North Atlantic (North Pacific) that relates to LF (HF) climate variability.

scholarly journals The burden of deleterious variants in a non-human primate biomedical model

2019 ◽  
Author(s):  
Vasily Ramensky ◽  
Anna J. Jasinska ◽  
Sandeep Deverasetty ◽  
Hannes Svardal ◽  
Ivette Zelaya ◽  
...  
Keyword(s):  
High Frequency ◽  
Model Systems ◽  
Whole Genome Sequence ◽  
Homozygous State ◽  
Protein Coding ◽  
Chlorocebus Aethiops ◽  
Sequencing Studies ◽  
The Caribbean ◽  
Caribbean Populations ◽  
Human Primate

ABSTRACTGenome sequencing studies of nonhuman primate (NHP) pedigree and population samples are discovering variants on a large and rapidly growing scale. These studies are increasing the utility of several NHP species as model systems for human disease. In particular, by identifying homozygous protein truncating variants (hPTVs) in genes hypothesized to play a role in causing human diseases, it may be possible to elucidate mechanisms for the phenotypic impact of such variants through investigations that are infeasible in humans. The Caribbean vervet (Chlorocebus aethiops sabaeus) is uniquely valuable for this purpose, as the dramatic expansion of its population following severe bottlenecks has enabled PTVs that passed through the bottleneck to attain a relatively high frequency. Using whole genome sequence (WGS) data from 719 monkeys of the Vervet Research Colony (VRC) extended pedigree, we found 2,802 protein-truncating alleles in 1,747 protein-coding genes present in homozygous state in at least one monkey. Polymorphic sites for 923 SNV hPTVs were also observed in natural Caribbean populations from which the VRC descends. The vervet genome browser (VGB) includes information on these PTVs, together with a catalog of phenotypes and biological samples available for monkeys who carry them. We describe initial explorations of the possible impact of vervet PTVs on early infant mortality.

Resistance to Antimicrobial Agents among Salmonella Isolates Recovered from Layer Farms and Eggs in the Caribbean Region

2014 ◽  
Vol 77 (12) ◽  
pp. 2153-2160 ◽  
Author(s):  
ABIODUN ADESIYUN ◽  
LLOYD WEBB ◽  
LISA MUSAI ◽  
BOWEN LOUISON ◽  
GEORGE JOSEPH ◽  
...  
Keyword(s):  
Multidrug Resistance ◽  
Trinidad And Tobago ◽  
High Frequency ◽  
Antimicrobial Agents ◽  
Farm Size ◽  
Diffusion Method ◽  
Caribbean Region ◽  
Resistance Patterns ◽  
The Caribbean ◽  
The Difference

This investigation determined the frequency of resistance of 84 isolates of Salmonella comprising 14 serotypes recovered from layer farms in three Caribbean countries (Trinidad and Tobago, Grenada, and St. Lucia) to eight antimicrobial agents, using the disc diffusion method. Resistance among isolates of Salmonella was related to the country of recovery, type of sample, size of layer farms, and isolate serotype. Overall, all (100.0%) of the isolates exhibited resistance to one or more of seven antimicrobial agents tested, and all were susceptible to chloramphenicol. The resistance detected ranged from 11.9% to sulphamethoxazole-trimethoprim (SXT) to 100.0% to erythromycin. The difference was, however, not statistically significant (P = 0.23). Across countries, for types of samples that yielded Salmonella, significant differences in frequency of resistance were detected only to SXT (P = 0.002) in Trinidad and Tobago and to gentamycin (P = 0.027) in St. Lucia. For the three countries, the frequency of resistance to antimicrobial agents was significantly different for ampicillin (P = 0.001) and SXT (P = 0.032). A total of 83 (98.8%) of the 84 isolates exhibited 39 multidrug resistance patterns. Farm size significantly (P = 0.032) affected the frequency of resistance to kanamycin across the countries. Overall, among the 14 serotypes of Salmonella tested, significant (P < 0.05) differences in frequency of resistance were detected to kanamycin, ampicillin, and SXT. Results suggest that the relatively high frequency of resistance to six of the antimicrobial agents (erythromycin, streptomycin, gentamycin, kanamycin, ampicillin, and tetracycline) tested and the multidrug resistance detected may pose prophylactic and therapeutic concerns for chicken layer farms in the three countries studied.

The Microstructure of Steatite (Protoenstatite)

1985 ◽  
Vol 43 ◽  
pp. 236-237
Author(s):  
W. E. Lee ◽  
A. H. Heuer
Keyword(s):  
High Frequency ◽  
Glass Ceramics ◽  
Magnesium Silicate ◽  
Beam Current ◽  
Glassy Matrix ◽  
Angle Of Incidence ◽  
X Ray ◽  
Mechanical And Electrical Properties ◽  
Argon Ions ◽  
High Temperature Polymorph

IntroductionTraditional steatite ceramics, made by firing (vitrifying) hydrous magnesium silicate, have long been used as insulators for high frequency applications due to their excellent mechanical and electrical properties. Early x-ray and optical analysis of steatites showed that they were composed largely of protoenstatite (MgSiO3) in a glassy matrix. Recent studies of enstatite-containing glass ceramics have revived interest in the polymorphism of enstatite. Three polymorphs exist, two with orthorhombic and one with monoclinic symmetry (ortho, proto and clino enstatite, respectively). Steatite ceramics are of particular interest a they contain the normally unstable high-temperature polymorph, protoenstatite.Experimental3mm diameter discs cut from steatite rods (∼10” long and 0.5” dia.) were ground, polished, dimpled, and ion-thinned to electron transparency using 6KV Argon ions at a beam current of 1 x 10-3 A and a 12° angle of incidence. The discs were coated with carbon prior to TEM examination to minimize charging effects.

Simulations of high-resolution images of amorphous silicon films

1986 ◽  
Vol 44 ◽  
pp. 544-545
Author(s):  
G. Y. Fan ◽  
J. M. Cowley
Keyword(s):  
Electron Microscope ◽  
High Frequency ◽  
Fourier Transformation ◽  
Amorphous Materials ◽  
Low Frequency ◽  
Chromatic Aberration ◽  
Structure Information ◽  
Frequency Components ◽  
High Resolution Images ◽  
Spatial Frequency Spectrum

It is well known that the structure information on the specimen is not always faithfully transferred through the electron microscope. Firstly, the spatial frequency spectrum is modulated by the transfer function (TF) at the focal plane. Secondly, the spectrum suffers high frequency cut-off by the aperture (or effectively damping terms such as chromatic aberration). While these do not have essential effect on imaging crystal periodicity as long as the low order Bragg spots are inside the aperture, although the contrast may be reversed, they may change the appearance of images of amorphous materials completely. Because the spectrum of amorphous materials is continuous, modulation of it emphasizes some components while weakening others. Especially the cut-off of high frequency components, which contribute to amorphous image just as strongly as low frequency components can have a fundamental effect. This can be illustrated through computer simulation. Imaging of a whitenoise object with an electron microscope without TF limitation gives Fig. 1a, which is obtained by Fourier transformation of a constant amplitude combined with random phases generated by computer.

SEM image sharpness analysis

1996 ◽  
Vol 54 ◽  
pp. 142-143
Author(s):  
M. T. Postek ◽  
A. E. Vladar
Keyword(s):  
High Frequency ◽  
Low Frequency ◽  
Quantitative Information ◽  
Primary Electron ◽  
Image Sharpness ◽  
Critical Dimensions ◽  
Sem Image ◽  
Frequency Changes ◽  
Electron Microscopes ◽  
Scanning Electron

Fully automated or semi-automated scanning electron microscopes (SEM) are now commonly used in semiconductor production and other forms of manufacturing. The industry requires that an automated instrument must be routinely capable of 5 nm resolution (or better) at 1.0 kV accelerating voltage for the measurement of nominal 0.25-0.35 micrometer semiconductor critical dimensions. Testing and proving that the instrument is performing at this level on a day-by-day basis is an industry need and concern which has been the object of a study at NIST and the fundamentals and results are discussed in this paper.In scanning electron microscopy, two of the most important instrument parameters are the size and shape of the primary electron beam and any image taken in a scanning electron microscope is the result of the sample and electron probe interaction. The low frequency changes in the video signal, collected from the sample, contains information about the larger features and the high frequency changes carry information of finer details. The sharper the image, the larger the number of high frequency components making up that image. Fast Fourier Transform (FFT) analysis of an SEM image can be employed to provide qualitiative and ultimately quantitative information regarding the SEM image quality.

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