305 research outputs found

    Targeting the Jamaican Ostionoid: The Blue Marlin Archaeological Project1

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    The study of Jamaica's earliest prehistory has yet to receive concentrated and widespread attention from archaeologists. One reason for this is that, until recently, too few professional archaeologists have existed on the island, and fewer still have been tempted by, or equipped for, the study of the island's prehistory. This situation is changing gradually as university-trained archaeologists continue to emerge in Jamaica, nonetheless, such a positive development is counteracted by a persistent negative: professional archaeologists outside Jamaica have generally not addressed the island's rich prehistoric resource. Thus, within the entire Caribbean, Jamaica remains one of the least known islands prehistorically . Even within the Greater Antilles, knowledge of Jamaica's pre-Columbian peoples lags behind that of Cuba, Haiti, the Dominican Republic, and Puerto Rico. The work of the Blue Marlin Archaeological Project on Jamaica's south coast

    Factorization in Formal Languages

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    We consider several novel aspects of unique factorization in formal languages. We reprove the familiar fact that the set uf(L) of words having unique factorization into elements of L is regular if L is regular, and from this deduce an quadratic upper and lower bound on the length of the shortest word not in uf(L). We observe that uf(L) need not be context-free if L is context-free. Next, we consider variations on unique factorization. We define a notion of "semi-unique" factorization, where every factorization has the same number of terms, and show that, if L is regular or even finite, the set of words having such a factorization need not be context-free. Finally, we consider additional variations, such as unique factorization "up to permutation" and "up to subset"

    Short-term variation in central corneal thick- ness and intraocular pressure using the Tono-Pachymeter NT530P (Tonopachy™)

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    Measurements of central corneal thickness (CCT) and intra-ocular pressure (IOP) are important for both diagnostic and therapeutic purposes. The aim of this study was to investigate the short-term variation and intra-subject repeatability of CCT and IOP measurements made with the Tono-Pachymeter NT530P (Tonopachy™). Fifty one consecutive automatic measurements of CCT and IOP were taken for the right eyes of 15 subjects (11 females and 4 males) aged 20 to 57 years (mean = 32.3 ± 13.5 years). The measured values (CCT and IOP) were compared against each other to establish the intra-subject repeatability and bias of each individual measurement with respect to the means, standard deviations and variances. Three different  statistical tests of normality: Kolmogorov-Smirnov (K-S),Lilliefors and Shapiro-Wilks (SW) tests suggested that most of the data was normally distributed,with a few exceptions. The inter-subject or overall mean values and standard deviations for the CCT and IOP samples were 528.2 ± 27.4 μm and 14.4 ±4.3 mmHg respectively. Although possible outliers increased the variability of the measurements of both parameters (CCT and IOP), the data generally showed good repeatability. The results of this study suggest that over short periods of time, the Tonopachy™ gives precise and repeatable measures of CCT and IOP. (S Afr Optom 2012 71(1) 12-21

    Comparison of polymerase chain reaction and bacterial culture for Salmonella detection in the Muscovy duck in Trinidad and Tobago

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    Objectives: The purpose of this study was to investigate the presence and serovar identity of Salmonella, at the national level, in farmed Muscovy ducks (Cairina moschata) in Trinidad and Tobago, and to compare the relative benefits of bacterial culture to those of polymerase chain reaction (PCR) for use in the routine detection and surveillance of Salmonella in these ducks. Methods: From March-September 2003, 110 fecal samples were collected from 82 farms across the islands of Trinidad and Tobago. Salmonella was isolated from fresh and frozen samples and the serotype of each was determined through bacterial culture. An in-house, nested PCR that detects all pathogenic Salmonella species was utilized in analyzing the samples. Results: Five samples were positive for Salmonella by bacterial culture, whereas 44 were positive by the nested PCR. Serovars isolated were Kiambu, Orion, Uganda, and two isolates from Group E1 whose H antigens could not be fully characterized. Of the samples, 87 (79%) gave equivalent PCR results for both enrichment broths-28 were positive for both and 59 were negative for both). However, 16 samples were positive for one broth, but not for the other, with the majority (14 of the 16) resulting positive for Selenite broth. PCR results for seven samples were inconclusive due to ambiguous band size or multiple bands near the expected band size. Conclusions: In Trinidad and Tobago, the Muscovy duck does not appear to be a significant source of S. typhimurium or S. enteritidis, but it does harbor other Salmonella species. In-house, nested PCR represents a simple, relatively inexpensive and potentially more sensitive method than bacterial culture for the routine surveillance of pathogenic Salmonella in the Muscovy duck

    Finite Automata for the Sub- and Superword Closure of CFLs: Descriptional and Computational Complexity

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    We answer two open questions by (Gruber, Holzer, Kutrib, 2009) on the state-complexity of representing sub- or superword closures of context-free grammars (CFGs): (1) We prove a (tight) upper bound of 2O(n)2^{\mathcal{O}(n)} on the size of nondeterministic finite automata (NFAs) representing the subword closure of a CFG of size nn. (2) We present a family of CFGs for which the minimal deterministic finite automata representing their subword closure matches the upper-bound of 22O(n)2^{2^{\mathcal{O}(n)}} following from (1). Furthermore, we prove that the inequivalence problem for NFAs representing sub- or superword-closed languages is only NP-complete as opposed to PSPACE-complete for general NFAs. Finally, we extend our results into an approximation method to attack inequivalence problems for CFGs

    An Exploratory Study of Methicillin-Resistant Staphylococcus aureus and SCCmec Elements Obtained from a Community Setting Along the Texas Border with Mexico

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    An exploratory study of methicillin-resistant Staphylococcus aureus (MRSA) and SCCmec elements in bacteria along the Mexican border of south Texas was performed. Between September and December of 2008, 375 swabs of anterior nares were self-collected by students attending the University of Texas-Pan American (UTPA) and cultured for MRSA. Fifty seven bacterial isolates were kept for further analysis that included suspected MRSA and other SCCmec-containing bacteria. Isolates were examined for the presence of nuc, mecA, lukS-PV, and spa genes using PCR. SCCmec and spa typing were also performed. Seven S. aureus isolates were found of which six were classified as MRSA. SCCmec typing showed five of the six MRSA strains to be type IV, while one MRSA strain, and most of the non-S. aureus strains, were untypeable, producing results that were indicative of mixed SCCmec types. Five of the six MRSA strains contained known spa types (two of which corresponded to USA300 and one to USA600), while one strain had a novel spa type. Only one isolate, a USA300 MRSA, was positive for lukS-PV. Easy access by the Texas border community to antibiotics in Mexico without a prescription, and the strong partition in SCCmec types between MRSA and non-S. aureus bacteria suggest that this border region of Texas may be uniquely suited for the study of emerging SCCmec types, their horizontal transfer, and perhaps other aspects of antibiotic resistance in bacteria

    Repetitions in infinite palindrome-rich words

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    Rich words are characterized by containing the maximum possible number of distinct palindromes. Several characteristic properties of rich words have been studied; yet the analysis of repetitions in rich words still involves some interesting open problems. We address lower bounds on the repetition threshold of infinite rich words over 2 and 3-letter alphabets, and construct a candidate infinite rich word over the alphabet ÎŁ2={0,1}\Sigma_2=\{0,1\} with a small critical exponent of 2+2/22+\sqrt{2}/2. This represents the first progress on an open problem of Vesti from 2017.Comment: 12 page

    A nested-PCR with an Internal Amplification Control for the detection and differentiation of Bartonella henselae and B. clarridgeiae: An examination of cats in Trinidad

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    BACKGROUND: Bartonella species are bacterial blood parasites of animals capable of causing disease in both animals and man. Cat-Scratch Disease (CSD) in humans is caused mainly by Bartonella henselae and is acquired from the cat, which serves as a reservoir for the bacteria. A second species, B. clarridgeiae is also implicated in the disease. Diagnosis of Bartonellosis by culture requires a week or more of incubation on enriched media containing blood, and recovery is often complicated by faster growing contaminating bacteria and fungi. PCR has been explored as an alternative to culture for both the detection and species identification of Bartonella, however sensitivity problems have been reported and false negative reactions due to blood inhibitors have not generally been addressed in test design. METHODS: A novel, nested-PCR was designed for the detection of Bartonella henselae and B. clarridgeiae based on the strategy of targeting species-specific size differences in the 16S-23S rDNA intergenic regions. An Internal Amplification Control was used for detecting PCR inhibition. The nested-PCR was utilized in a study on 103 blood samples from pet and stray cats in Trinidad. RESULTS: None of the samples were positive by primary PCR, but the Nested-PCR detected Bartonella in 32/103 (31%) cats where 16 were infected with only B. henselae, 13 with only B. clarridgeiae and 3 with both species. Of 22 stray cats housed at an animal shelter, 13 (59%) were positive for either or both species, supporting the reported increased incidence of Bartonella among feral cats. CONCLUSION: The usefulness of a single PCR for the detection of Bartonella henselae and B. clarridgeiae in the blood of cats is questionable. A nested-PCR offers increased sensitivity over a primary PCR and should be evaluated with currently used methods for the routine detection and speciation of Bartonella henselae and B. clarridgeiae. In Trinidad, B. henselae and B. clarridgeiae are the predominant species in cats and infection appears highest with stray cats, however B. clarridgeiae may be present at levels similar to that of B. henselae in the pet population
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