Showing papers by "University of Connecticut published in 1994"

Evolution, weighting, and phylogenetic utility of mitochondrial gene sequences and a compilation of conserved polymerase chain reaction primers

Abstract: DNA-sequence data from the mitochondrial genome are being used with increasing frequency to estimate phylogenetic relationships among animal taxa. The advantage to using DNA-sequence data is that many of the processes governing the evolution and inheritance of DNA are already understood. DNA data, however, do not guarantee the correct phylogenetic tree because of problems associated with shared ancestral polymorphisms and multiple substitutions at single nucleotide sites. Knowledge of evolutionary processes can be used to improve estimates of patterns of relationships and can help to assess the phylogenetic usefulness of individual genes and nucleotides. This article reviews molecular processes, discusses the correction of genetic distances and the weighting of DNA data, and provides an assessment of the phylogenetic usefulness of specific mitochondrial genes. The Appendix presents a compilation of conserved polymerase chain reaction primers that can be used to amplify virtually any gene in the mitochondrial genome. DNA data sets vary tremendously in degree of phylogenetic usefulness. Correction or weighting (or both) of DNA-sequence data based on level of variability can improve results in some cases. Gene choice is of critical importance. For studies of relationships among closely related species, the use of ribosomal genes can be problematic, whereas unconstrained sites in protein coding genes appear to have fewer problems. In addition, information from studies of amino acid substitutions in rapidly evolving genes may help to decipher close relationships. For intermediate levels of divergence where silent sites contain many multiple hits, amino acid changes can be useful for construction phylogenetic relationships. For deep levels of divergence, protein coding genes may be saturated at the amino acid level and highly conserved regions of ribosomal RNA and transfer RNA genes may be useful. Because of the arbitrariness of taxonomic categories, no sweeping generalizations can be made about the taxonomic rank at which particular genes are useful. As more DNA-sequence data accumulate, we will be able to gain an even better understanding of the way in which genes and species evolve.

Estimating Terrestrial Biodiversity through Extrapolation

Abstract: Both the magnitude and the urgency of the task of assessing global biodiversity require that we make the most of what we know through the use of estimation and extrapolation. Likewise, future biodiversity inventories need to be designed around the use of effective sampling and estimation procedures, especially for 'hyperdiverse' groups of terrestrial organisms, such as arthropods, nematodes, fungi, and microorganisms. The challenge of estimating patterns of species richness from samples can be separated into (i) the problem of estimating local species richness, and (ii) the problem of estimating the distinctness, or complementarity, of species assemblages. These concepts apply on a wide range of spatial, temporal, and functional scales. Local richness can be estimated by extrapolating species accumulation curves, fitting parametric distributions of relative abundance, or using non-parametric techniques based on the distribution of individuals among species or of species among samples. We present several of these methods and examine their effectiveness for an example data set. We present a simple measure of complementarity, with some biogeographic examples, and outline the difficult problem of estimating complementarity from samples. Finally, we discuss the importance of using 'reference' sites (or sub-sites) to assess the true richness and composition of species assemblages, to measure ecologically significant ratios between unrelated taxa, to measure taxon/sub-taxon (hierarchical) ratios, and to 'calibrate' standardized sampling methods. This information can then be applied to the rapid, approximate assessment of species richness and faunal or floral composition at 'comparative' sites.

A new, semi-structured psychiatric interview for use in genetic linkage studies: a report on the reliability of the SSAGA.

Abstract: Within- and cross-center test-retest studies were conducted to study the reliability of a new, semistructured, comprehensive, polydiagnostic psychiatric interview being used in a multisite genetic linkage study of alcoholism. Findings from both studies indicated that reliability for the Semi-Structured Assessment for the Genetics of Alcoholism (SSAGA) was high for DSM-III-R substance dependence disorders, but less so for substance abuse disorders. Reliability of depression was good in both studies, but mixed for antisocial personality disorder (ASP). Findings are presented in terms of specific substance dependence and abuse diagnoses, as well as for depression and ASP. Criterion-specific reliabilities are examined by type of substance used. Although SSAGA was designed to provide for broad phenotyping of alcoholism, review of its new features suggests its suitability for a variety of family studies, not just those focusing on substance abuse.

Blind identification and equalization based on second-order statistics: a time domain approach

Abstract: A new blind channel identification and equalization method is proposed that exploits the cyclostationarity of oversampled communication signals to achieve identification and equalization of possibly nonminimum phase (multipath) channels without using training signals. Unlike most adaptive blind equalization methods for which the convergence properties are often problematic, the channel estimation algorithm proposed here is asymptotically ex-set. Moreover, since it is based on second-order statistics, the new approach may achieve equalization with fewer symbols than most techniques based only on higher-order statistics. Simulations have demonstrated promising performance of the proposed algorithm for the blind equalization of a three-ray multipath channel. >

Urinary indices of hydration status.

Abstract: Athletes and researchers could benefit from a simple and universally accepted technique to determine whether humans are well-hydrated, euhydrated, or hypohydrated. Two laboratory studies (A, B) and one field study (C) were conducted to determine if urine color (Ucol) indicates hydration status accurately and to clarify the interchangeability of Ucol, urine osmolality (Uosm), and urine specific gravity (Usg) in research. Ucol, Uosm, and Usg were not significantly correlated with plasma osmolality, plasma sodium, or hematocrit. This suggested that these hematologic measurements are not as sensitive to mild hypohydration (between days) as the selected urinary indices are. When the data from A, B, and C were combined, Ucol was strongly correlated with Usg and Uosm. It was concluded that (a) Ucol may be used in athletic/industrial settings or field studies, where close estimates of Usg or Uosm are acceptable, but should not be utilized in laboratories where greater precision and accuracy are required, and (b) Uosm and Usg may be used interchangeably to determine hydration status.

Authenticity and positivity strivings in marriage and courtship.

Abstract: We proposed that married persons would want their spouses to see them as they saw themselves but that dating persons would want their relationship partners to evaluate them favorably. A survey of 176 married and dating couples tested these predictions. Just as married persons were most intimate with spouses whose evaluations verified their self-views, dating persons were most intimate with partners who evaluated them favorably. For married people with negative self-views, then, intimacy increased as their spouses evaluated them more negatively. Marriage apparently precipitates a shift from a desire for positive evaluations to a desire for self-verifying evaluations.

Investigating the “Glass Ceiling” Phenomenon: An Empirical Study of Actual Promotions to Top Management

Abstract: Although a “glass ceiling” is said to keep women from the top management levels of organizations, no research has investigated actual decisions about promotions to such positions. This study examin...

A Developmental View of Academic Advising As Teaching

Abstract: This classic article, upon which many of the subsequent articles reflect, originally appeared in January of 1972 in the Journal of College Student Personnel (volume 13,pp. 12–17) and is reprinted with both permission and deep appreciation. Crookston's article i as based on a paper he presented at a conference on academic advising at Temple Buell College in Denver in July 1970.

Optical pattern recognition for validation and security verification

Abstract: We propose an idea for security verification of credit cards, passports, and other forms of identification so that they cannot easily be reproduced. A new scheme of complex phase/amplitude patterns that cannot be seen and cannot be copied by an intensity-sensitive detector such as a CCD camera is used. The basic idea is to permanently and irretrievably bond a phase mask to a primary identification amplitude pattern such as a fingerprint, a picture of a face, or a signature. Computer simulation results and tests of the proposed system are provided to verify that both the phase mask and the primary pattern are separately readable and identifiable in an optical processor or correlator.

Photophysics of the carotenoids associated with the xanthophyll cycle in photosynthesis

Abstract: Green plants use the xanthophyll cycle to regulate the flow of energy to chlorophylla within photosynthetic proteins. Under conditions of low light intensity violaxanthin, a carotenoid possessing nine conjugated double bonds, functions as an antenna pigment by transferring energy from its lowest excited singlet state to that of chlorophylla within light-harvesting proteins. When the light intensity increases, violaxanthin is biochemically transformed into zeaxanthin, a carotenoid that possesses eleven conjugated double bonds. The results presented here show that extension of the ⧄ conjugation of the polyene lowers the energy of the lowest excited singlet state of the carotenoid below that of chlorophylla. As a consequence zeaxanthin can act as a trap for the excess excitation energy on chlorophylla pigments within the protein, thus regulating the flow of energy within photosynthetic light-harvesting proteins.

(R)-methanandamide: a chiral novel anandamide possessing higher potency and metabolic stability.

Abstract: Four chiral congeners of arachidonylethanolamide (anandamide) have been synthesized and evaluated for (a) their ability to bind to the cannabinoid receptor in rat forebrain membranes and (b) their pharmacological potency as measured by the compounds' ability to inhibit electrically-evoked contractions of the mouse vas deferens. The lead analog was also tested for its potency in vivo. Of the analogs tested, (R)-(+)-arachidonyl-1'-hydroxy-2'-propylamide [(R)-methanandamide] exhibited the highest affinity for the cannabinoid receptor with a Ki of 20 +/- 1.6 nM, 4-fold lower than that of anandamide (Ki = 78 +/- 2 nM). Moreover, determination of the cannabinoid binding affinity in the presence and absence of the protease inhibitor phenylmethanesulfonyl fluoride (PMSF) revealed that (R)-methanandamide possesses a remarkable stability to aminopeptidase hydrolysis. Pharmacological studies on mouse isolated vasa deferentia demonstrated that all four analogs produce concentration-related inhibition of the twitch response and the order of potency is the same as the rank order of the affinities of these agonists for cannabinoid binding sites. Furthermore, experiments with mice have demonstrated that (R)-methanandamide also possesses cannabimimetric properties in vivo, as established by the four tests of hypothermia, hypokinesia, ring immobility, and antinociception.

Extending modern portfolio theory into the domain of corporate diversification: Does it apply?

Abstract: It is widely held that diversification lowers a firm's unsystematic (business-specific) risk but does not affect its systematic (systemwide) risk. We tested each notion while controlling for other ...

The Role of Subject-Matter Knowledge and Interest in the Processing of Linear and Nonlinear Texts

Abstract: Sixty-six studies were reviewed that met several a priori criteria. Specifically, the studies had to be empirical investigations that related to a particular academic domain and that involved connected discourse presented either in traditional written form or on computer. In addition, the studies had to incorporate some measure of both knowledge and interest. The resulting body of literature was first summarized and analyzed in terms of the domains chosen, the subjects selected, the nature of the texts used, the manner in which knowledge and interest were assessed, and the principal outcomes reported. Next, from this analysis, six premises were proposed as guides for future research and practice. Finally, concluding remarks were advanced that address the overall significance of text-processing research that interactively considers the domain of knowledge and the interest of the reader.

Visual lexical access is initially phonological: I. Evidence from associative priming by words, homophones, and pseudohomophones

Abstract: In 9 experiments, a target word (e.g., frog) was named following an associate (TOAD), or a word (e.g., TOWED) or nonword (e.g., TODE) homophonic with the associate. At brief (e.g., 50 ms) stimulus onset asynchronies (SOAs), the 3 primes produced equal associative priming. At a long SOA (250 ms), priming by TOAD was matched by TODE but not by TOWED. Equal priming at brief SOAs by the 3 primes and no priming by orthographic controls (TOLD, TORD) suggests that lexical access is initially phonological. TOWED priming less than TODE at SOA = 250 ms suggests that phonologically activated representations whose input orthography does not match the addressed spelling (available only for words) are eventually suppressed. Phonological constraints on lexical access precede and set the stage for orthographic constraints.

Culture and clinical care. Folk illness beliefs and behaviors and their implications for health care delivery.

Abstract: This article presents an approach to the evaluation of patient-held beliefs and behaviors that may not be concordant with those of biomedicine. Physicians and patients often hold discrepant models of health and illness that may affect the effectiveness of communication during the clinical visit. An extreme example of such a discrepancy exists when the patient feels that he or she has an illness that is not defined within the biomedical paradigm. These are commonly referred to as folk illnesses. An example of such an illness is provided in order to discuss the effects of folk beliefs on patient-held perceptions of health and sickness, treatment-seeking behavior, clinical care, and physician-patient communication. Guidelines for addressing clinical issues surrounding folk beliefs and behaviors in a culturally sensitive way are discussed. ( JAMA . 1994;271:690-694)

Insider Lending: Banks, Personal Connections, and Economic Development in Industrial New England

Abstract: Acknowledgements Introduction 1 Vehicles for accumulating capital 2 Insider lending and Jacksonian hostility towards banks 3 Engines of economic development 4 The decline of insider lending and the problem of determining creditworthiness 5 Professionalization and specialization 6 The merger movement in banking Conclusion

Immediate implant surgery: three-year retrospective evaluation of 50 consecutive cases.

Abstract: Since August 1989, 35 consecutive patients were treated with immediate implants to replace 50 teeth requiring extractions as a result of root fractures, endodontic instability, nonrestorable carious lesions, or periodontal disease. Defects relative to the implant were morphologically grouped and were treated for bone regeneration with demineralized freeze-dried crushed cancellous bone (DFDBA), e-PTFE membrane, or both. Thread exposure initially ranged from 4 to 20 threads, while implant lengths varied from 8.5 to 18 mm. The mean implant length was 15 mm, with mean thread exposure of 11.34 threads, or 54% of the threaded length of the implant. Reentry confirmed 100% thread coverage in all but one implant in the no-wall group treated with DFDBA alone. Histologic evaluation of three cases confirmed viability of the regenerated bone. The patients were followed through April 1993, with 49 implants (98%) remaining osseointegrated and functional, supporting the predictability of immediate implant placement. The age of the patients ranged from 16 to 80 years, hence implant placement considerations relative to adolescents are also discussed.

Signal peptides: exquisitely designed transport promoters

Abstract: Prokaryotic proteins destined for transport out of the cytoplasm typically contain an N-terminal extension sequence, called the signal peptide, which is required for export. It is evident that many secretory proteins utilize a common export system, yet the signal sequences themselves display very little primary sequence homology. In attempting to understand how different signal peptides are able to promote protein secretion through the same pathway, the physical features of natural signal sequences have been extensively examined for similarities that might play a part in function. Experimental data have confirmed statistical analyses which highlighted dominant features of natural signal sequences in Escherichia coli: a net positive charge in the N-terminus increases efficiency of transport; the core region must maintain a threshold level of hydrophobicity within a range of length limitations; the central portion adopts an alpha-helical conformation in hydrophobic environments; and the signal cleavage region is ideally six residues long, with small side-chain amino acids in the -1 and -3 positions. This review focuses on the parallels between signal peptide physical features and their functions, which emerge when the results of a variety of experimental approaches are combined. The requirement for each property may be ascribed to a potential interaction that is critical for efficient protein export. The summation of the key physical features produces signal peptides with the flexibility to function in multiple roles in order to expedite secretion. In this way, nature has indeed evolved exquisitely tuned signal sequences.