Showing papers by "University of Connecticut published in 1995"
TL;DR: A new optical encoding method of images for security applications is proposed and it is shown that the encoding converts the input signal to stationary white noise and that the reconstruction method is robust.
Abstract: We propose a new optical encoding method of images for security applications. The encoded image is obtained by random-phase encoding in both the input and the Fourier planes. We analyze the statistical properties of this technique and show that the encoding converts the input signal to stationary white noise and that the reconstruction method is robust.
2,361 citations
TL;DR: Current issues are laid out and the areas of consensus and controversy surrounding the evolution of plasticity and the reaction norm (the set of phenotypes produced by a genotype over a range of environments) are summarized.
Abstract: Phenotypic plasticity is an environmentally based change in the phenotype. Understanding the evolution of adaptive phenotypic plasticity has been hampered by dissenting opinions on the merits of different methods of description, on the underlying genetic mechanisms, and on the way that plasticity is affected by natural selection in a heterogeneous environment. During much of this debate, the authors of this article have held opposing views. Here, we attempt to lay out current issues and summarize the areas of consensus and controversy surrounding the evolution of plasticity and the reaction norm (the set of phenotypes produced by a genotype over a range of environments).
1,361 citations
TL;DR: A novel role for amino acid neurotransmitters in regulating neocortical neurogenesis is found, and applied alone, GABAA and AMPA/kainate receptor antagonists increase DNA synthesis, indicating that endogenously released amino acids influence neocorticals progenitors in the cell cycle.
1,067 citations
TL;DR: A new blind identification algorithm based solely on the system outputs is proposed and necessary and sufficient identifiability conditions in terms of the multichannel systems and the deterministic input signal are presented.
Abstract: Conventional blind channel identification algorithms are based on channel outputs and knowledge of the probabilistic model of channel input. In some practical applications, however, the input statistical model may not be known, or there may not be sufficient data to obtain accurate enough estimates of certain statistics. In this paper, we consider the system input to be an unknown deterministic signal and study the problem of blind identification of multichannel FIR systems without requiring the knowledge of the input statistical model. A new blind identification algorithm based solely on the system outputs is proposed. Necessary and sufficient identifiability conditions in terms of the multichannel systems and the deterministic input signal are also presented.
830 citations
TL;DR: The results indicate that interspecific differences in sapling mortality are critical components of forest community dynamics and the importance of these effects is demonstrated through a spatially explicit simulator of forest dynamics (SORTIE).
Abstract: With a view toward understanding species-specific differences in juvenile tree mortality and the community-level implications of these differences, we characterized juvenile survivorship of 10 dominant tree species of oak transition-northern hardwood forests using species-specific mathematical models. The mortality models predict a sapling's probability of dying as a function of its recent growth history. These models and species-specific growth functions (published elsewhere), characterize a species' shade tolerance. Combined growth and mortality models express a sapling's probability of mortality as a function of light availability. We describe the statistical bases and the field methods used to calibrate the mortality models. We examined inter- and intraspecific variation in juvenile mortality across three sites: Great Mountain Forest (low pH, nutrient poor soils) in northwestern Connecticut, a calcareous bedrock region (neutral pH, nutrient rich soils) also in northwestern Connecticut, and a site in central-western Michigan (low pH, nutrient poor soils). Interspecific differences in juvenile mortality have profound effects on community dynamics and composition; the importance of these effects is demonstrated through a spatially explicit simulator of forest dynamics (SORTIE). The 10 species we examined occupy a continuum of survivorship levels at 1% of full sun. There was surprisingly little intraspecific variation in mortality functions for sugar maple, American beech, eastern hemlock, and white ash between the Great Mountain and Michigan sites. However, there was a striking increase in survivorship for sugar maple in the calcareous site. Differences in survivorship among the sites are correlated with soil pH and presumably nutrient availability. Growth rates in high-light and low-light survivorship are inversely correlated across species; as level of shade tolerance increases, a species grows more slowly in high light and exhibits increased survivorship under low light. Our results indicate that interspecific differences in sapling mortality are critical components of forest community dynamics.
829 citations
TL;DR: The data from both nursing home and community-dwelling subjects indicate a strong relationship of lower extremity strength to balance and gait, and an association between these functions and the occurrence of falls.
Abstract: We studied the effects of lower extremity strength as well as gait and balance on the occurrence of falls in nursing home residents. Nursing home residents with a history of falls had less than half of the knee and ankle strength of nonfalling subjects residing in the same home. The differences were more prominent at the ankle than the knee, and were most pronounced in the ankle dorsiflexors, where they were one-tenth that of controls. Also of note was the fact that this same group of fallers had slowed gait velocity (58% of control) as well as an impaired response to postural perturbation as determined on the Postural Stress Test (55% of control). In a recently completed study we measured strength as balance (EquiTest balance platform) of community-dwelling subjects. The occurrence of loss of balance during the sensory organization test was correlated with diminished lower extremity (Pearson R = -.36, p = .001) as well as ankle dorsi and plantar flexion moments (Pearson R = -.37, p = .001). Using a logistic regression model, we demonstrated an independent effect of strength on the odds ratio of an SOT-LOB; for each newtonmeter per kg increase in strength there was a 20% decrease (95% CI, .74-87) in the odds ratio. The data from both nursing home and community-dwelling subjects indicate a strong relationship of lower extremity strength to balance and gait. The nursing home studies demonstrated an association between these functions and the occurrence of falls.(ABSTRACT TRUNCATED AT 250 WORDS)
659 citations
TL;DR: Laser cooling of a single Be ion held in a rf (Paul) ion trap to where it occupies the quantum-mechanical ground state of motion is reported, with the use of resolved-sideband stimulated Raman cooling.
Abstract: We report laser cooling of a single $^{9}\mathrm{Be}^{+}$ ion held in a rf (Paul) ion trap to where it occupies the quantum-mechanical ground state of motion. With the use of resolved-sideband stimulated Raman cooling, the zero point of motion is achieved 98% of the time in 1D and 92% of the time in 3D. Cooling to the zero-point energy appears to be a crucial prerequisite for future experiments such as the realization of simple quantum logic gates applicable to quantum computation.
612 citations
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TL;DR: An activist role in the community that encourages and supports zero tolerance for domestic violence will help stop this epidemic and crime.
582 citations
TL;DR: A recursive equation is derived to combine a variable number of family history reports, wherein the probabilities associated with a single report are computed from the logistic analysis, which permits the use offamily history information both as a proxy for an uninterviewed relative, as well as a second source of information to be used in the analysis of genetic family data.
Abstract: Using data from The Collaborative Study on the Genetics of Alcoholism, we compare direct interview diagnoses of alcohol dependence to those obtained by history from family members. Using a requirement of three or more positive implications by history, the specificity, sensitivity, and positive predictive values are 98%, 39%, and 45%, respectively. A logistic analysis found the gender of the relative and alcoholism in the informant to be significant, but not the gender of the informant. The partial odds ratio of a diagnosis at interview associated with a positive family history diagnosis was 13.6. The relationship between the informant and relative was significant, with negative reports from an offspring or mate more influential than a negative report from a parent or second-degree relative. We derived a recursive equation to combine a variable number of family history reports, wherein the probabilities associated with a single report are computed from the logistic analysis. This permits the use of family history information both as a proxy for an uninterviewed relative, as well as a second source of information to be used in the analysis of genetic family data.
485 citations
TL;DR: In this paper, the expression and function of integrin subunits in unfertilized mouse eggs were investigated and it was shown that the integrin alpha 6 beta 1 was a cell-cell adhesion receptor that mediates sperm-egg binding.
457 citations
TL;DR: A self-report measure, the Child Abuse and Trauma Scale, is described, which yields a quantitative index of the frequency and extent of various types of negative experiences in childhood and adolescence, suggesting that the construct of psychological maltreatment underlies the destructive elements of numerous forms of abuse and neglect.
TL;DR: It is argued that strict separation between chaotic and stochastic dynamics in ecological systems is unnecessary and misleading, and a more comprehensive approach is presented for systems subject to Stochastic perturbations.
Abstract: Chaos is usually regarded as a distinct alternative to random effects such as environmental fluctuations or external disturbances. We argue that strict separation between chaotic and stochastic dynamics in ecological systems is unnecessary and misleading, and we present a more comprehensive approach for systems subject to stochastic perturbations. The defining property of chaos is sensitive dependence on initial conditions. Chaotic systems are "noise amplifiers" that magnify perturbations; nonchaotic systems are "noise mufflers" that dampen perturbations. We also present statistical methods for detecting chaos in time-series data, based on using nonlinear time-series modeling to estimate the Lyapunov exponent λ, which gives the average rate at which perturbation effects grow (λ > 0) or decay (λ < 0). These methods allow for dynamic noise and can detect low-dimensional chaos with realistic amounts of data. Results for natural and laboratory populations span the entire range from noise-dominated and strongl...
TL;DR: This paper found that phonological deficits consistently accompany reading problems whether they occur in relatively pure form or in the presence of coexisting attention deficit or arithmetic disability, and this difficulty stemmed in large part from the same weakness in the phonological component that underlies reading disability.
Abstract: A comprehensive cognitive appraisal of elementary school children with learning disabilities showed that within the language sphere, deficits associated with reading disability are selective Phonological deficits consistently accompany reading problems whether they occur in relatively pure form or in the presence of coexisting attention deficit or arithmetic disability Although reading-disabled children were also deficient in production of morphologically related forms, this difficulty stemmed in large part from the same weakness in the phonological component that underlies reading disability In contrast, tests of syntactic knowledge did not distinguish reading-disabled children from those with other cognitive disabilities, nor from normal children after covarying for intelligence
TL;DR: The sit-to-stand test is a practical alternative to manual muscle testing and various instrumented options and several procedures for performing the test are presented in this review.
Abstract: When the intent is to quantify performance of lower extremity muscles, the sit-to-stand test is a practical alternative to manual muscle testing and various instrumented options. Several procedures for performing the test are presented in this review as is information relevant to test interpretation. Performance variables known to be associated with sit-to-stand performance are noted.
TL;DR: The authors argues that neither institutional structure is the panacea its supporters claim, and that both firms and networks, of which there are several kinds, can be successful, growth-promoting adaptations to the competitive environment.
TL;DR: Analyses of the nature of the in vivo host immune response to the vaccine revealed that the peptide-pulsed APCs are capable of inducing autologous melanoma-reactive and the nonapeptide-specific CTLs in situ at the immunization site and at distant metastatic disease sites.
Abstract: Human melanoma cells can process the MAGE-1 gene product and present the processed nonapeptide EADPTGHSY on their major histocompatibility complex class I molecules, HLA-A1, as a determinant for cytolytic T lymphocytes (CTLs). Considering that autologous antigen presenting cells (APCs) pulsed with the synthetic nonapeptide might, therefore, be immunogenic, melanoma patients whose tumor cells express the MAGE-1 gene and who are HLA-A1+ were immunized with a vaccine made of cultured autologous APCs pulsed with the synthetic nonapeptide. Analyses of the nature of the in vivo host immune response to the vaccine revealed that the peptide-pulsed APCs are capable of inducing autologous melanoma-reactive and the nonapeptide-specific CTLs in situ at the immunization site and at distant metastatic disease sites.
TL;DR: In this paper, the authors present simple hierarchical centring reparametrisations that often give improved convergence for a broad class of normal linear mixed models, including the Laird-Ware model, and a general structure for hierarchically nested linear models.
Abstract: SUMMARY The generality and easy programmability of modern sampling-based methods for maximisation of likelihoods and summarisation of posterior distributions have led to a tremendous increase in the complexity and dimensionality of the statistical models used in practice. However, these methods can often be extremely slow to converge, due to high correlations between, or weak identifiability of, certain model parameters. We present simple hierarchical centring reparametrisations that often give improved convergence for a broad class of normal linear mixed models. In particular, we study the two-stage hierarchical normal linear model, the Laird-Ware model for longitudinal data, and a general structure for hierarchically nested linear models. Using analytical arguments, simulation studies, and an example involving clinical markers of acquired immune deficiency syndrome (AIDS), we indicate when reparametrisation is likely to provide substantial gains in efficiency.
TL;DR: The intent of this minireview is to help microbiologists and molecular geneticists visualize the relationship between b-lactamase mutations and three-dimensional structure.
Abstract: In the last decade the usefulness of the oximino-b-lactams and monobactams has been compromised by the increasing presence of clinically derived extended-spectrum b-lactamases (10, 16, 40, 41, 53, 65, 74). Especially alarming are studies that describe isolates resistant to mechanism-based b-lactamase inhibitors of the clavulanate type (3, 4, 6, 62, 88). With the atomic-level detail that X-ray crystallography is now providing about the tertiary structures of the class A (or group 2) b-lactamases, it is becoming possible to rationalize how a particular amino acid change might alter the substrate profile and catalytic parameters. The intent of this minireview, therefore, is to help microbiologists and molecular geneticists visualize the relationship between b-lactamase mutations and three-dimensional structure. Although extended-spectrum b-lactamases from both chromosomal and plasmid genes are known (40, 67, 85), the focus here is on the better-characterized plasmidmediated TEM and SHV-type b-lactamases of class A.
TL;DR: This review will center on developments in the study of nonsyncopal falls among community-dwelling older adults since 1987, as several large, prospective studies of risk factors for falls and interventions to prevent falls have been published in the past 8 years.
Abstract: alls are common, often dreaded events in the lives of older F people and are an important focus of both research and clinical care. Nonsyncopal falls have been defined as events “which result in a person coming to rest inadvertently on the ground or other lower level and other than as a consequence of . . . sustaining a violent blow, loss of consciousness, sudden onset of paralysis, as in a stroke, [or] an epileptic seizure.’” The majority of nonsyncopal falls do not have well defined etiologies and are often felt to be the result of multiple interacting factors. Although most people who fall do not suffer major adverse consequences, falls can result in serious injuries, including fractures, or death. More often, falls result in restriction of mobility or activity and can lead to loss of independence. There have been a number of recently published reviews about falls in older and falls in the nursing home.’ This review will center on developments in the study of nonsyncopal falls among community-dwelling older adults since 1987, as several large, prospective studies of risk factors for falls and interventions to prevent falls have been published in the past 8 years. The adverse consequences of falls, and the complex relationship of falls, fall injuries, and functional decline, will be discussed. Factors that increase the risk of falling and the risk of injury with a fall, as well as their implications for medical care, will be examined. Interventions to reduce the risk of falls and injury in older people will be reviewed, and future areas of investigation will be addressed.
TL;DR: In this paper, the properties of films of these blends were evaluated using differential scanning calorimetry, dynamic mechanical thermal analysis and Instron tensile testing, and compared with similar blend films made with poly(3hydroxybutyrate-co-3-hydroxyvalerate) (PHBV, 11.6% HV content).
TL;DR: Accurate reproducible agreement among experienced board-certified oral pathologists diagnosing oral epithelial dysplasia is difficult to achieve.
Abstract: Objectives Pathologists differ in their definition of “dysplasia’. This study was done to test the hypothesis that experienced oral pathologists are consistent in diagnosing epithelial dysplasia. Study Design Six board-certified oral pathologists examined 120 oral biopsies exhibiting simple hyperkeratosis to severe dysplasia. No clinical information was given, and presence of dysplasia was judged by histomorphology. Examiners' diagnoses were compared with sign-out diagnoses for each case. Months later, each examiner viewed 60 relabeled slides from the original 120. Each diagnosis was compared with the diagnosis in the first round. Results Exact agreement with the sign-out diagnosis averaged 50.5% (within one histologic grade 90.4%). Examiners agreed exactly with their own diagnoses 50.8% of the time (within one histologic grade 92.4%). Agreement distinguishing dysplasia from no dysplasia compared with original sign-out diagnosis was 81.5%. Agreement with themselves distinguishing dysplasia from no dysplasia was 80.3%. Conclusions Accurate reproducible agreement among experienced board-certified oral pathologists diagnosing oral epithelial dysplasia is difficult to achieve.
TL;DR: A new ``second generation" reconstruction algorithm for irregular sampling, i.e. for the problem of recovering a band-limited function from its non-uniformly sampled values, is presented.
Abstract: Summary. We present a new “second generation” reconstruction algorithm for irregular sampling, i.e. for the problem of recovering a band-limited function from its non-uniformly sampled values. The efficient new method is a combination of the adaptive weights method which was developed by the two first named authors and the method of conjugate gradients for the solution of positive definite linear systems. The choice of ”adaptive weights” can be seen as a simple but very efficient method of preconditioning. Further substantial acceleration is achieved by utilizing the Toeplitztype structure of the system matrix. This new algorithm can handle problems of much larger dimension and condition number than have been accessible so far. Furthermore, if some gaps between samples are large, then the algorithm can still be used as a very efficient extrapolation method across the gaps.
TL;DR: The results suggest that Listeria spp.
TL;DR: In this paper, the authors distinguish between incremental and relative information content, and propose a new regression-based test for relative information contents, which applies to both returns and valuation studies, generalizes to any number of predictor variables, and can be used in conjunction with White's adjustment for heteroskedasticity.
Abstract: . This study distinguishes between incremental and relative information content. Incremental comparisons ask whether one accounting measure provides information content beyond that provided by another, and apply when one measure is viewed as given and an assessment is desired regarding the incremental contribution of another (e.g., a supplemental disclosure). Relative comparisons ask which measure has greater information content, and apply when making mutually exclusive choices among alternatives, or when rankings by information content are desired (e.g., when comparing alternative disclosures). Questions of both incremental and relative information content arise frequently in accounting. However, few previous studies have examined questions of relative information content. Possible explanations include unfamiliarity with the relative versus incremental distinction, and the additional statistical complexity involved in testing for relative information content.
First, we examine analytically the relation between incremental and relative information content, demonstrating that they address different research questions and require different tests for statistical significance. Second, we identify accounting research contexts in which questions of relative and incremental information content arise. Third, we propose a new regression-based test for relative information content. This test applies to both returns and valuation studies, generalizes to any number of predictor variables, and can be used in conjunction with White's (1980) adjustment for heteroskedasticity. Fourth, we illustrate tests for relative and incremental information content in a familiar research setting that compares the information contents of net income, cash flows, and net sales in 40 industries.
Resume. Les auteurs etablissent la distinction entre le contenu marginal et relatif en information. Les comparaisons du contenu marginal visent a determiner si une mesure comptable livre un contenu en information superieur a celui d'une autre, et elles s'appliquent dans les cas ou une mesure est consideree comme etant donnee et ou l'on souhaite evaluer la contribution marginale d'une autre mesure (par exemple, la presentation de renseignements complementaires). Les comparaisons du contenu relatif visent a determiner quelle mesure livre un contenu en information superieur, et elles s'appliquent dans les cas ou les choix entre differentes possibilites sont mutuellement exclusifs ou lorsqu'il s'agit d'etablir des classifications selon le contenu en information (par exemple, dans la comparaison de differentes possibilites en ce qui a trait a la presentation d'information). La question du contenu marginal aussi bien que du contenu relatif en information se pose frequemment en comptabilite. Dans les etudes realisees jusqu'a maintenant, l'on s'est peu interesse aux questions touchant le contenu relatif en information. Cette lacune pourrait s'expliquer, entre autres, par le caractere inusite de la distinction entre contenu relatif et contenu marginal en information et par la complexite statistique accrue que supposent des tests portant sur le contenu relatif en information.
Selon un schema analytique, les auteurs examinent en premier lieu la relation entre le contenu marginal et le contenu relatif en information, en demontrant que les mesures correspondantes se rapportent a des questions de recherche differentes et qu'elles exigent des tests de signification statistique differents. Ils determinent en deuxieme lieu quels sont les contextes de recherche comptable dans lesquels se posent les questions pertinentes au contenu relatif et marginal en information. Ils proposent, en troisieme lieu, un test inedit fonde sur la regression et s'appliquant au contenu relatif en information. Ce test convient a la fois aux etudes de rendement et aux etudes d'evaluation, peut etre generalise a n'importe quel nombre de variables predictives et peut etre utilise en association avec l'ajustement de White (1980) relatif a l'heteroscedasticite. Ils illustrent, en quatrieme lieu, l'application de tests du contenu relatif et marginal en information dans un contexte de recherche familier ou le contenu informationnel du benefice net, des flux de tresorerie et du chiffre d'affaires net est compare dans 40 entreprises.
TL;DR: The finding of a highly surface-active, deoxysugar-rich polysaccharide material that can be rapidly (<0.5 h) and selectively extracted by bubble adsorption is significant, as it is apparent that this material played important roles in particle stickiness and TEP formation in the tank, and thus it may, at times, play similar roles in particles aggregation in the sea.
Abstract: A study was undertaken to evaluate the role of exocellular polysaccharides in the flocculation of a marine diatom bloom in a large tank mesocosm. Surface-active organic matter was extracted from 1.0 μ-filtered tank water by bubble adsorption each day for 7 days of the experiment. In agreement with past studies, particles (3–51 urn equivalent spherical diameter) were readily formed by bubbling and became concentrated in the foam. At the beginning of the bubbling (0–0.5 h), both particles and surface-active carbohydrates were extracted at high rates; however, these rates dropped off steeply after about 0.5 h of bubbling. The rate of particle formation by bubbling could be modeled fairly well by second order kinetics. The extracted, surface-active material was enriched in deoxysugars and galactose, while the residual material was enriched in glucose. Extracted surface-active carbohydrates reached a maximum of 33% of the total dissolved sugars ( 0.99) with particle stickiness (alpha). In addition, the concentration of surface-active carbohydrates was well correlated (2 = 0.91) with the concentration of transparent exopolymer particles (TEP) in the tank, and it was demonstrated that TEP could be copiously formed by bubbling of 1.0 μm-filered seawater. The finding of a highly surface-active, deoxysugar-rich polysaccharide material that can be rapidly (<0.5 h) and selectively extracted by bubble adsorption is significant, as it is apparent that this material played important roles in particle stickiness and TEP formation in the tank, and thus it may, at times, play similar roles in particle aggregation in the sea.
TL;DR: In this paper, two simple balance scales comprising three or four familiar tests of static balance were developed, and their validity and reliability were described, such that the relative difficulties of the basic tests were taken into consideration.
Abstract: Background Two simple balance scales comprising three or four familiar tests of static balance were developed, and their validity and reliability are described. The scales were such that the relative difficulties of the basic tests were taken into consideration. Methods Using FICSIT data, Fisher's method was used to construct scales combining ability to maintain balance in parallel, semi-tandem, tandem, and one-legged stances. Reliability was inferred from the stability of the measure over 3-4 months. Construct validity was assessed by cross-sectional correlations. Results Test-retest reliability (over 3-4 months) was good (r = .66). Validity of the FICSIT-3 scale was suggested by its low correlation with age, its moderate to high correlations with physical function measures, and three balance assessment systems. The FICSIT-4 scale discriminated balance over a wide range of health status; the three-test scale had a substantial ceiling effect in community samples. Conclusion A balance scale was developed that appears to have acceptable reliability, validity, and discriminant ability.
01 Jun 1995
TL;DR: The results temper recent assertions concerning the overwhelming importance of bacterial biomass in the oligotrophic Sargasso Sea but still support a major role for these microorganisms in the open ocean as repositories for carbon and nutrients.
Abstract: Seawater samples were collected from the euphotic zone of the Sargasso Sea near Bermuda in August of 1989 and March–April of 1990. Microbial population abundances, chlorophyll concentration, particulate carbon and particulate nitrogen were measured. Calculations were performed to establish the relative and absolute importance of the various microbial assemblages. The choice of conversion factors (g C and N cell −1 , or g C and N μm −3 ) for the microbial populations dramatically affected the estimation of “living” and “detrital” particulate material in the samples, and the relative importance of the various microbial groups. Averaged over all samples on either of the two cruises, microbial biomass constituted a greater proportion of the total particulate carbon and nitrogen during March–April (55% and 63%, respectively), than during August (≈24% and 30%, respectively) using “constrained” conversion factors that were derived. Accordingly, detrital material constituted the bulk of the particulate material during August, but was similar to the amount of microbial biomass during March–April. The bacterial assemblage constituted the largest single pool of microbial carbon (35%) and nitrogen (45%) in the water, and a significant fraction of the total particulate carbon (≈10–20%) and nitrogen (≈15–30%). Phototrophic nanoplankton (microalgae 2–20 μm in size) were second in overall biomass, and often dominated the microbial biomass in the deep chlorophyll maxima that were present during both cruises. The results temper recent assertions concerning the overwhelming importance of bacterial biomass in the oligotrophic Sargasso Sea but still support a major role for these microorganisms in the open ocean as repositories for carbon and nutrients.
TL;DR: In this paper, a method for determining how much bias results from dyadic interdependence is presented, which depends on the type of design and the degree of nonindependence, while the number of dyads in the study ordinarily has only small effect on bias.
Abstract: Relationship researchers regularly gather data from both members of the dyad, and these two scores are likely to be correlated. This nonindependence of observations can bias p values in significance testing if person is the unit in the statistical analysis. A method for determining how much bias results from dyadic interdependence is presented. Correction factors based on the degree of interdependence, design type, and the number of dyads are used to adjust the F statistic and its degrees of freedom to produce a corrected p value. Bias depends on the type of design and the degree of nonindependence, while the number of dyads in the study ordinarily has only a small effect on bias. Various strategies for controlling for nonindependence are briefly reviewed.
TL;DR: In this paper, the authors use Eulerian and Lagrangian models and a simple analytical model to study the processes important in spray dispersion and evaporation within the droplet eva-oration layer (DEL).
Abstract: The part that sea spray plays in the air-sea transfer of heat and moisture has been a controversial question for the last two decades. With general circulation models (GCMs) suggesting that perturbations in the Earth's surface heat budget of only a few W m−2 can initiate major climatic variations, it is crucial that we identify and quantify all the terms in that heat budget. Thus, here we review recent work on how sea spray contributes to the sea surface heat and moisture budgets. In the presence of spray, the near-surface atmosphere is characterized by a droplet evaporation layer (DEL) with a height that scales with the significant-wave amplitude. The majority of spray transfer processes occur within this layer. As a result, the DEL is cooler and more moist than the atmospheric surface layer would be under identical conditions but without the spray. Also, because the spray in the DEL provides elevated sources and sinks for heat and moisture, the vertical heat fluxes are no longer constant with height. We use Eulerian and Lagrangian models and a simple analytical model to study the processes important in spray droplet dispersion and evaporation within this DEL. These models all point to the conclusion that, in high winds (above about 15 m/s), sea spray begins to contribute significantly to the air-sea fluxes of heat and moisture. For example, we estimate that, in a 20-m/s wind, with an air temperature of 20°C, a sea surface temperature of 22°C, and a relative humidity of 80%, the latent and sensible heat fluxes resulting from the spray alone will have magnitudes of order 150 and 15 W/m2, respectively, in the DEL. Finally, we speculate on what fraction of these fluxes rise out of the DEL and, thus, become available to the entire marine boundary layer.
TL;DR: Direct electron transfer is reported for myoglobin in films of didodecyldimethylammonium bromide on platinum, tin-doped indium oxide, and gold electrodes and results suggest that electron transfer in the Mb-DDAB films may be facilitated partly by strong adsorption of surfactants on electrodes.
Abstract: In previous work, greatly enhanced rates of electron transfer were found for myoglobin (Mb) in ordered films of surfactants on pyrolytic graphite (PG) electrodes. Direct electron transfer is now reported for Mb in films of didodecyldimethylammonium bromide (DDAB) on platinum, tin-doped indium oxide, and gold electrodes. Rates of electron transfer in these films were similar on all electrodes. In the absence of surfactant, electron transfer was observed on bare electrodes only when Mb was purified by chromatography, and only on hydrophilic tin-doped In 2 O 3 or PG. Treatment of tin-doped In 2 O 3 or PG electrodes with unpurified protein solutions blocked electron transfer to Mb in the purified solutions. Reflectance-absorbance infrared and X-ray photoelectron spectroscopy revealed proteinaceous adsorbates on electrodes exposed to unpurified solutions of Mb. This adsorbate blocks electron transfer to Mb and to ferricyanide in solution. Results suggest that electron transfer in the Mb-DDAB films may be facilitated partly by strong adsorption of surfactants on electrodes. Surfactant adsorbed at electrode-film interfaces appears to inhibit adsorption of macromolecules from Mb solutions which could otherwise block electron transfer between Mb and electrodes.