Can an inertial measurement unit, combined with machine learning, accurately measure ground reaction forces in cricket fast bowling?

This study examined whether an inertial measurement unit (IMU) could measure ground reaction force (GRF) during a cricket fast bowling delivery. Eighteen male fast bowlers had IMUs attached to their upper back and bowling wrist. Each participant bowled 36 deliveries, split into three different intensity zones: low = 70% of maximum perceived bowling effort, medium = 85%, and high = 100%. A force plate was embedded into the bowling crease to measure the ground truth GRF. Three machine learning models were used to estimate GRF from the IMU data. The best results from all models showed a mean absolute percentage error of 22.1% body weights (BW) for vertical and horizontal peak force, 24.1% for vertical impulse, 32.6% and 33.6% for vertical and horizontal loading rates, respectively. The linear support vector machine model had the most consistent results. Although results were similar to other papers that have estimated GRF, the error would likely prevent its use in individual monitoring. However, due to the large differences in raw GRFs between participants, researchers may be able to help identify links among GRF, injury, and performance by categorising values into levels (i.e., low and high).

The relationship between bowling intensity and ground reaction force in cricket pace bowlers

This study examined the relationship between perceived bowling intensity, ball release speed and ground reaction force (measured by peak force, impulse and loading rate) in male pace bowlers. Twenty participants each bowled 36 deliveries, split evenly across three perceived intensity zones: low = 70% of maximum perceived bowling effort, medium = 85%, and high = 100%. Peak force and loading rate were significantly different across the three perceived intensity zones in the horizontal and vertical directions (Cohen's d range = 0.14-0.45, p < 0.01). When ball release speed increased, peak force and loading rate also increased in the horizontal and vertical directions (η_p² = 0.04-0.18, p < 0.01). Lastly, bowling at submaximal intensities (i.e., low - medium) was associated with larger decreases in peak horizontal force (7.9-12.3% decrease), impulse (15.8-21.4%) and loading rate (7.4-12.7%) compared to decreases in ball release speed (5.4-8.3%). This may have implications for bowling strategies implemented during training and matches, particularly for preserving energy and reducing injury risk.

Quantifying cricket fast bowling volume, speed and perceived intensity zone using an Apple Watch and machine learning

This study examined whether an inertial measurement unit (IMU) and machine learning models could accurately measure bowling volume (BV), ball release speed (BRS), and perceived intensity zone (PIZ). Forty-four male pace bowlers wore a high measurement range, research-grade IMU (SABELSense) and a consumer-grade IMU (Apple Watch) on both wrists. Each participant bowled 36 deliveries, split into two different PIZs (Zone 1 = 70-85% of maximum bowling effort, Zone 2 = 100% of maximum bowling effort). BRS was measured using a radar gun. Four machine learning models were compared. Gradient boosting models had the best results across all measures (BV: F-score = 1.0; BRS: Mean absolute error = 2.76 km/h; PIZ: F-score = 0.92). There was no significant difference between the SABELSense and Apple Watch on the same hand when measuring BV, BRS, and PIZ. A significant improvement in classifying PIZ was observed for IMUs located on the dominant wrist. For all measures, there was no added benefit of combining IMUs on the dominant and non-dominant wrists.

Emergence of a non-sporulating secondary phenotype in Clostridium (Clostridioides) difficile ribotype 078 isolated from humans and animals

Clostridium (Clostridioides) difficile is a Gram positive, spore forming anaerobic bacterium that is a leading cause of antibiotic associated diarrhoea in the developed world. C. difficile is a genetically diverse species that can be divided into 8 phylogenetically distinct clades with clade 5 found to be genetically distant from all others. Isolates with the PCR ribotype 078 belong to clade 5, and are often associated with C. difficile infection in both humans and animals. Colonisation of animals and humans by ribotype 078 raises questions about possible zoonotic transmission, and also the diversity of reservoirs for ribotype 078 strains within the environment. One of the key factors which enables C. difficile to be a successful, highly transmissible pathogen is its ability to produce oxygen resistant spores capable of surviving harsh conditions. Here we describe the existence of a non-sporulating variant of C. difficile ribotype 078 harbouring mutations leading to premature stop codons within the master regulator, Spo0A. As sporulation is imperative to the successful transmission of C. difficile this study was undertaken to investigate phenotypic characteristics of this asporogenous phenotype with regards to growth rate, antibiotic susceptibility, toxin production and biofilm formation.

Cricket fast bowling detection in a training setting using an inertial measurement unit and machine learning

Fast bowlers are at a high risk of overuse injuries. There are specific bowling frequency ranges known to have negative or protective effects on fast bowlers. Inertial measurement units (IMUs) can classify movements in sports, however, some commercial products can be too expensive for the amateur athlete. As a large number of the world's population has access to an IMU (e.g. smartphones), a system that works on a range of different IMUs may increase the accessibility of automated workload monitoring in sport. Seventeen elite fast bowlers in a training setting were used to train and/or validate five machine learning models by bowling and performing fielding drills. The accuracy of machine learning models trained using data from all three bowling phases (pre-delivery, delivery and post-delivery) were compared to those trained using only the delivery phase at a sampling rate of 250 Hz. Next, models were trained using data down-sampled to 125 Hz, 50 Hz, and 25 Hz to mimic results from lower specification sensors. Models trained using only the delivery phase showed similar accuracy (> 95%) to those trained using all three bowling phases. When delivery-phase data were down-sampled, the accuracy was maintained across all models and sampling frequencies (>96%).

Early HIV disclosure and nondisclosure among men and women on antiretroviral treatment in Uganda

Efforts to expand access to HIV care and treatment often stress the importance of disclosure of HIV status to aid adherence, social support, and continued resource mobilization. We argue that an examination of disclosure processes early in the process of seeking testing and treatment can illuminate individual decisions and motivations, offering insight into potentially improving engagement in care and adherence. We report on baseline data of early HIV disclosure and nondisclosure, including reasons for and responses to disclosure from a cohort of men and women (n=949) currently accessing antiretroviral treatment in two regions of Uganda. We found early disclosures at the time of suspicion or testing positive for HIV by men and women to be largely for the purposes of emotional support and friendship. Responses to these selected disclosures were overwhelmingly positive and supportive, including assistance in accessing treatment. Nonetheless, some negative responses of worry, fear, or social ostracism did occur. Individuals deliberately chose to not disclose their status to partners, relatives, and others in their network, for reasons of privacy or not wanting to cause worry from the other person. These data demonstrate the strategic choices that individuals make early in the course of suspicion, testing, and treatment for HIV to mobilize resources and gain emotional or material support, and similarly their decisions and ability to maintain privacy regarding their status.

Phosphonoacetate biosynthesis: in vitro detection of a novel NADP(+)-dependent phosphonoacetaldehyde-oxidizing activity in cell-extracts of the marine Roseovarius nubinhibens ISM

A novel phosphonoacetaldehyde-oxidizing activity was detected in cell-extracts of the marine bacterium Roseovarius nubinhibens ISM grown on 2-aminoethylphosphonic acid (2-AEP; ciliatine). Extracts also contained 2-AEP transaminase and phosphonoacetate hydrolase activities. These findings indicate the existence of a biological route from 2-AEP via phosphonoacetaldehyde for the production of phosphonoacetate, which has not previously been shown to be a natural product. The three enzymes appear to constitute a previously-unreported pathway for the mineralization of 2-AEP which is a potentially important source of phosphorus in the nutrient-stressed marine environment.

Stimulation of phosphate uptake and polyphosphate accumulation by activated sludge microorganisms in response to sulfite addition

Enhanced phosphate removal from wastewaters is dependent on the synthesis and intracellular accumulation of polyphosphate by sludge microorganisms. However the role played by polyphosphate in microbial metabolism and the factors that trigger its formation remain poorly-understood. Many examples of the accumulation of the biopolymer by environmental microorganisms are documented; these include a recent report of the presence of large polyphosphate inclusions in sulfur-oxidizing marine bacteria. To investigate whether any link might exist outside the marine environment between the presence of reduced sulfur compounds and enhanced levels of microbial phosphate uptake and polyphosphate accumulation, activated sludge cultures were grown under laboratory conditions in media that contained sulfite, thiosulfate, hydrosulfite or tetrathionate. Only in the presence of sulfite was there any evidence of a stimulatory effect; in medium that contained 0.5 mM sodium sulfite some 17% more phosphate was removed by the sludge, whilst there was an almost two-fold increase in intracellular polyphosphate levels. No indications of sulfite toxicity were observed.

Evidence for phosphonate usage in the coral holobiont

Phosphonates are characterized by a stable carbon-phosphorus bond and commonly occur as lipid conjugates in invertebrate cell membranes. Phosphonoacetate hydrolase encoded by the phnA gene, catalyses the cleavage of phosphonoacetate to acetate and phosphate. In this study, we demonstrate the unusually high phnA diversity in coral-associated bacteria. The holobiont of eight coral species tested positive when screened for phnA using degenerate primers. In two soft coral species, Sinularia and Discosoma, sequencing of the phnA gene showed 13 distinct groups on the basis of 90% sequence identity across 100% of the sequence. A total of 16 bacterial taxa capable of using phosphonoacetate as the sole carbon and phosphorus source were isolated; 8 of which had a phnA+ genotype. This study enhances our understanding of the wide taxonomic and environmental distribution of phnA, and highlights the importance of phosphonates in marine ecosystems.

Effect of reduced pH on inorganic polyphosphate accumulation by Burkholderia cepacia complex isolates

AIMS

Burkholderia cepacia complex (Bcc) isolates causing pulmonary infection in cystic fibrosis (CF) patients grow within an acidic environment in the lung. As exposure to acid pH has been shown to increase intracellular inorganic polyphosphate (polyP) formation in some bacteria, we investigated the inter-relationship between acidic pH and polyP accumulation in Bcc isolates.

METHODS AND RESULTS

The formation of polyP by one Burkholderia cenocepacia clinical isolate was initially examined at a range of pH values by measuring total intracellular polyP accumulation and phosphate uptake. The pattern of polyP accumulation corresponded with the pattern of phosphate uptake with the maximum for both occurring at pH 5.5. Phosphate uptake and formation of polyP by this isolate was further determined over 48 h at pH 5.5, 6.5 and 7.5; formation of polyP was maximal at pH 5.5 at all time points studied. Sixteen of 17 additional clinical and environmental Bcc isolates examined also exhibited maximum phosphate uptake at pH 5.5.

CONCLUSIONS

Both clinical and environmental Bcc isolates, of five genomovars, show enhanced formation of polyP in an acidic environment. Given both the speculated role of polyP in pathogenesis, cell signalling and biofilm formation and the acidic nature of the CF lung, this may be of considerable clinical importance.

SIGNIFICANCE AND IMPACT OF THE STUDY

Growth of Bcc in an acidic environment, such as that found in the lungs of CF patients may be influenced in part by polyP accumulation.

An evaluation of three new-generation tetrazolium salts for the measurement of respiratory activity in activated sludge microorganisms

XTT (3'-[1-[(phenylamino)-carbonyl]-3,4-tetrazolium]-bis(4-methoxy-6-nitro)benzenesulfonic acid hydrate), MTS (3-(4,5-dimethylthiazol-2-yl)-5-(3-carboxymethoxyphenyl)-2-(4-sulfophenyl)-2H-tetrazolium, inner salt), and WST-1 (4-(3-4-iodophenyl)-2-(4-nitrophenyl)-2H-5-tetrazolio)-1,3-benzenedisulfonate) are tetrazolium salts that have become commercially available only in relatively recent years; they differ from earlier such compounds in that their reduction gives rise to a formazan product that is water soluble. We have established the sites in the prokaryotic respiratory chain at which each of the dyes is reduced to its corresponding formazan and have evaluated the suitability of each for the colorimetric estimation of electron transport system activity in populations of activated sludge microorganisms. Reduction of all three tetrazolium salts was shown to be proportional to cell biomass and oxygen uptake and to be susceptible to low levels of the reference toxicant 3,5-dichlorophenol. XTT, which was not inhibitory at concentrations of up to 2 mM and was reduced by 91% of isolates from a sample of culturable activated sludge bacteria, was chosen for further assay development. XTT-formazan production was found to be stimulated by the availability of an exogenous carbon and energy source, and by the presence of the electron-coupling agent phenazine methosulfate. Less than 3% of XTT reduction by an activated sludge sample was abiotic. An assay based on this compound could be a valuable and simple tool for the routine monitoring of the performance of wastewater treatment systems.

Enhanced phosphate uptake and polyphosphate accumulation in Burkholderia cepacia grown under low pH conditions

Of bacterial cells in a sample of activated sludge, 34% contained detectable intracellular polyphosphate inclusions following Neisser staining, when grown on glucose/mineral salts medium at pH 5.5; at pH 7.5 only 7% of cells visibly accumulated polyphosphate. In a sludge isolate of Burkholderia cepacia chosen for further study, maximal removal of phosphate and accumulation of polyphosphate occurred at pH 5.5; levels were up to 220% and 330% higher, respectively, than in cells grown at pH 7.5. During the early stationary phase of growth at pH 5.5 a maximum level of intracellular polyphosphate that comprised 13.6% of cellular dry weight was reached. Polyphosphate kinase activity was detected in actively growing cells only when cultured at pH 5.5. The phenomenon of acid-stimulated phosphate uptake and polyphosphate accumulation in this environmental bacterial population parallels observations previously made by us in the yeast Candida humicola and may thus represent a widespread microbial response to low external pH values.

Acid-stimulated phosphate uptake by activated sludge microorganisms under aerobic laboratory conditions

Activated sludge inocula taken from five different wastewater treatment plants were grown aerobically under laboratory conditions on mineral salts medium containing either glucose or skimmed milk powder as carbon source. Cultures showed increases of between 50% and 143% in levels of phosphate uptake from the medium when the growth pH was 5.5 rather than 7.5. Of 100 individual sludge microbial isolates studied, 34 demonstrated such acid-stimulated luxury phosphate uptake; the optimum pH for the process was shown to lie between 5.0 and 6.5. Enhanced phosphate removal by these isolates was accompanied by increases of between 2 and 10.5-fold in their polyphosphate content; this was visualised as intracellular inclusions. Acid-stimulated luxury phosphate uptake by environmental microorganisms is a previously-unrecognised phenomenon that may have application in novel technologies for nutrient removal from wastewaters.

Knowledge about vaccine trials and willingness to participate in an HIV/AIDS vaccine study in the Ugandan military

In preparation for HIV vaccine trials, knowledge about vaccines, willingness to participate in a vaccine study, and motivations for participation must be assessed. The Preparation for AIDS Vaccine Evaluation study assessed knowledge about vaccines and vaccine trials and willingness to participate in a hypothetical trial in 1,182 Ugandan military men (aged 18-30 years). Participants received education about vaccine trials and were interviewed during 24 months of follow-up observation. Its key findings are that: 1) throughout follow-up, most participants expressed willingness to participate in a hypothetical HIV vaccine trial; 2) participants are familiar with vaccines but do not clearly distinguish the use of vaccines for prevention or curing; 3) the most common reason given for being interested in participating in a vaccine trial was to be protected from HIV/AIDS; 4) trials' procedures (e.g., placebos, randomization, and blinding) were unfamiliar; and 5) knowledge about trials' procedures increased incrementally over follow-up, but at different rates for different concepts. These data demonstrate that potential vaccine trials' participants may benefit from vaccine trial education if adequate time is allowed to ensure that participants are able to master the complex information required for trial participation.

Organized sports for children and preadolescents

Participation in organized sports provides an opportunity for young people to increase their physical activity and develop physical and social skills. However, when the demands and expectations of organized sports exceed the maturation and readiness of the participant, the positive aspects of participation can be negated. The nature of parental or adult involvement can also influence the degree to which participation in organized sports is a positive experience for preadolescents. This updates a previous policy statement on athletics for preadolescents and incorporates guidelines for sports participation for preschool children. Recommendations are offered on how pediatricians can help determine a child's readiness to participate, how risks can be minimized, and how child-oriented goals can be maximized.

Prevalence of acanthosis nigricans and its association with hyperinsulinemia in New Mexico adolescents

PURPOSE

To determine whether the association between acanthosis nigricans (AN) and hyperinsulinemia is independent of obesity and other variables.

METHODS

A convenience sample of 675 New Mexico middle school students was screened to determine the presence of AN, obesity, and other variables, including: ethnicity, parental history of diabetes, and level of physical activity. Fasting glucose and insulin levels were drawn on 233 students to determine the association between risk factors and hyperinsulinemia.

RESULTS

Acanthosis nigricans (AN) was present in 18.9% of students screened. Twenty-one percent of the subsample had hyperinsulinemia. Based on these results, the estimated prevalence of hyperinsulinemia among all middle school students in New Mexico was 8.9%. Forty-seven percent (47.2%) of students who had AN and were obese had hyperinsulinemia, compared with 2.4% of students who did not have either of these conditions. In multiple logistic regression analysis, AN and obesity were independently and positively associated with hyperinsulinemia, whereas physical activity was protective.

CONCLUSIONS

The high prevalence of risk factors in this population makes diabetes prevention a priority for public health action. AN screening is an easily performed, noninvasive method for identifying adolescents at risk for type 2 diabetes.

Developing AIDS vaccine trials educational programs in Uganda

In preparation for HIV vaccine trials, data on a cohort's knowledge about vaccines and vaccine studies are required so as to tailor educational materials to adequately meet local needs. Interviews (n = 1,182) conducted as part of a 3-year prospective study of Ugandan military men aged 18 to 30 years determined what information, in addition to standard trials information, would be required to ensure comprehension of trial procedures. The interviews highlighted four points: (1) the cohort has a lot of knowledge about vaccines but conflates whether vaccines cure or prevent disease; (2) there is a general lack of knowledge about clinical trials procedures; (3) the desire to be protected from HIV/AIDS is a common reason for being willing to participate in a hypothetical vaccine trial; and (4) concern about side effects is a common reason for being unwilling to participate in a trial. These four points guided the focus of the vaccine trials education, which used locally appropriate analogies to introduce complex unfamiliar concepts such as placebos and blinding. This case study highlights the value of incorporating baseline interviews to assess the educational needs of study populations.

Intracellular accumulation of polyphosphate by the yeast Candida humicola G-1 in response to acid pH

Cells of a newly isolated environmental strain of Candida humicola accumulated 10-fold more polyphosphate (polyP), during active growth, when grown in complete glucose-mineral salts medium at pH 5.5 than when grown at pH 7.5. Neither phosphate starvation, nutrient limitation, nor anaerobiosis was required to induce polyP formation. An increase in intracellular polyP was accompanied by a 4.5-fold increase in phosphate uptake from the medium and sixfold-higher levels of cellular polyphosphate kinase activity. This novel accumulation of polyP by C. humicola G-1 in response to acid pH provides further evidence as to the importance of polyP in the physiological adaptation of microbial cells during growth and development and in their response to environmental stresses.

Biodegradation of phosphonomycin by Rhizobium huakuii PMY1

The biodegradation by Rhizobium huakuii PMY1 of up to 10 mM phosphonomycin as a carbon, energy, and phosphorus source with accompanying P(i) release is described. This biodegradation represents a further mechanism of resistance to this antibiotic and a novel, phosphate-deregulated route for organophosphonate metabolism by Rhizobium spp.

Common bile duct ligation in the rat: a model of intrapulmonary vasodilatation and hepatopulmonary syndrome

Hepatopulmonary syndrome (HPS) causes impaired oxygenation due to intrapulmonary vasodilatation in patients with cirrhosis. Chronic common bile duct ligation (CBDL) in the rat results in gas-exchange abnormalities similar to HPS, but intrapulmonary vasodilatation has not been evaluated. We assess intrapulmonary vasodilatation, measured in vivo, after CBDL. Sham, 2- and 5-wk CBDL, and 3-wk partial portal vein ligated (PVL) rats had hepatic and lung injury, portal pressure, and arterial blood gases assessed. The pulmonary microcirculation was evaluated by injecting microspheres (size range 5.5-10 microm) intravenously and measuring the size and number of microspheres bypassing the lungs in arterial blood. CBDL animals developed progressive hepatic injury and portal hypertension accompanied by gas-exchange abnormalities and intrapulmonary vasodilatation. PVL animals, with a similar degree of portal hypertension, did not develop intrapulmonary vasodilatation or abnormal gas exchange. No lung injury was observed. CBDL, but not PVL, causes progressive intrapulmonary vasodilatation, which accompanies worsening arterial gas exchange. These findings validate CBDL as a model to study HPS.

The purification and properties of phosphonoacetate hydrolase, a novel carbon-phosphorus bond-cleavage enzyme from Pseudomonas fluorescens 23F

A novel, inducible, carbon-phosphorus bond-cleavage enzyme, phosphonoacetate hydrolase, was purified from cells of Pseudomonas fluorescens 23F grown on phosphonoacetate. The native enzyme had a molecular mass of approximately 80 kDa and, upon SDS/PAGE, yielded a homogenous protein band with an apparent molecular mass of about 38 kDa. Activity of purified phosphonoacetate hydrolase was Zn2+ dependent and showed pH and temperature optima of approximately 7.8 and 37 degrees C, respectively. The purified enzyme had an apparent Km of 1.25 mM for its sole substrate phosphonoacetate, and was inhibited by the structural analogues 3-phosphonopropionate and phosphonoformate. The NH2-terminal sequence of the first 19 amino acids displayed no significant similarity to other databank sequences.

Secretory IgA in cervical mucus

PURPOSE

Sexually active adolescent girls are uniquely vulnerable to sexually transmitted disease, including cervical cancer and AIDS. Little is known about the development of genital immunity in adolescents. Secretory IgA (sIgA) in cervical mucus is an important component of genital immunity. We studied sIgA levels in cervical mucus samples for both adolescent and adult females.

METHODS

Samples were collected in a university-based adolescent medicine clinic and a university student health center. Participants consisted of 13 sexually active adolescent girls and fourteen adult controls. Samples were collected in the course of routine pelvic exams. All subjects were at least two years post menarche. Mucus was aspirated directly from the cervical os. Diluted samples were liquefied with a proteolytic enzyme (bromelain). Secretory IgA levels were measured by radial immunodiffusion using IgA2 from pooled human plasma as a standard.

RESULTS

Secretory IgA levels for the adolescent group (mean 0.157 g/L SD 0.080) were slightly lower than for the adult group mean (0.199 g/L SD 0.130) although not statistically significant.

CONCLUSIONS

Cervical sIgA levels were comparable between sexually active adolescents and adults.

Anthropology and AIDS: the cultural context of sexual risk behavior among urban Baganda women in Kampala, Uganda

One hundred and thirty Baganda women (65 HIV antibody positive and 65 HIV antibody negative), recruited from the Makerere University-Case Western Reserve University Collaborative Pediatric follow-up clinic in Kampala, Uganda were interviewed about cultural rules and norms for sexual behavior and HIV-specific risk behaviors. Interviews were analyzed for themes related to sexual risk, cultural rules regarding sex, and individual sexual practices. Statistical relationships were tested using chi 2 and t-test statistics. The mean age of the women was 21 years (range 15-30). Despite sexual norms prohibiting sex for women outside marriage, subjects reported that there are certain circumstances when a woman may take other partners, including economic need, desire for greater sexual satisfaction, or revenge on a husband with other partners. Cases were more likely to state that women may have outside partners for economic reasons (P < 0.05) and that women have outside partners for sexual satisfaction (P < 0.01). Women interviewed for this study are complying with Ugandan AIDS control messages to 'zerograze' and 'stick to one partner'. Fear of AIDS remains high, however, because women fear that their partners have not responded to risk reduction messages. Of those women stating fear of AIDS, 57% of cases and 62% of controls based their fear on their perceptions of their partners' activities. Therefore, women feel that they remain at risk of infection despite their own behavior change. We find that, while the potential for risk reduction is high for these women, cultural norms permitting males to have multiple partners limit a woman's ability to control her risk reduction. Important conclusions are: (1) a focus on women's behavior alone is not sufficient as both partners must respond to risk reduction messages; (2) knowledge about AIDS is not sufficient to achieve change in sexual behavior because sexual behavior is linked to economics, gender relations, and other complex socio-cultural factors; and (3) a study of Baganda male sexual values and behavior is urgently needed.

AIDS and the urban family: its impact in Kampala, Uganda

Twenty-two families with one or more adult members with AIDS were extensively interviewed about sociodemographic variables, knowledge of AIDS, responses to AIDS, material needs, psychological state and perception of stigma. A total of 24 individuals were enrolled. Seven subjects did not permit contact with family members. Of the 24 subjects, four denied that they have AIDS, four informed everyone in the household of the AIDS diagnosis, eight told no one at all, and eight told some of their family. Subjects reportedly did not tell their family because the family would worry, they feared rejection, it is none of their business or they wouldn't understand. Family members expressed fear of loss, shock and disbelief at the diagnosis, but did not reject the subject or fear infection. Persons with AIDS and their families expressed fear of rejection from those outside the household due to the perceived stigma associated with AIDS. The labelling of someone as having AIDS relates to their physical condition, so with declining health, subjects and their families may avoid outside contacts. A direct impact of AIDS is to diminish mobility, decreasing available economic resources. These data indicate the importance of assisting families responsible for caring for AIDS patients.

The biological impact of social responses to the AIDS epidemic

This paper examines the extent to which social responses to the AIDS epidemic contribute to the continued transmission of the virus, thereby exacerbating the biological impact of the epidemic. Following the model of McGrath (1991), social responses to AIDS are examined in terms of their impact on potential transmission of HIV. Responses are evaluated using established criteria for decreasing disease transmission: eliminating the source of infection, eliminating contact necessary for infection, decreasing susceptibility of hosts, or decreasing the infectivity of infectious persons. The most frequent responses to AIDS have been scapegoating, resulting in ostracism, stigma, and blame; resignation; use of alternative therapies; political mobilization; and research. With the exception of political mobilization in some communities, the social responses to AIDS have not decreased the biological impact of the epidemic, and, therefore, may not be "biologically appropriate".

Biological impact of social disruption resulting from epidemic disease

Whereas previous research on the disruptive effects of epidemic disease have focused on the ways in which epidemics affect social structure and function, this study focuses on the biological impact of social disruption. The hypothesis is that social disruption resulting from the occurrence of epidemic disease increases the biological impact of the epidemic, as assessed by disease incidence. This hypothesis is explored in terms of a "level of response" model, borrowed from Slobodkin and Rapoport (Q. Rev. Biol. 49:181-200, 1974). The Human Area Relations File (HRAF) provides ethnographic reports of social responses to epidemics. The most frequently reported response in the HRAF is flight or migration away from the locus of the epidemic, followed in frequency by extraordinary preventive and/or therapeutic measures and scapegoating. The model proposes a continuum of responses beginning with responses that are already part of the indigenous response to disease and proceeding through disruptive processes, including flight and rejection of authority systems. Social disruption increases the biological impact of epidemics by robbing the social group of important participants, dismantling public health programs, or producing general economic hardship. The model proposes a scheme for identification of situations under which particular social group responses are "biologically appropriate."

Social networks of disease spread in the lower Illinois valley: a simulation approach

This study illustrates the use of disease modeling and simulation techniques to the study of the spread of disease within and between social networks. A Reed-Frost type model of disease spread is used to construct a simulation of the spread of tuberculosis within three prehistoric populations of the Lower Illinois River Valley during Middle Woodland, Late Woodland, and Mississippian times. A high and low population size was modeled for each time period. Late Woodland model 2 (low population estimate) is the only model that experienced pathogen extinction with host survival. The rest of the models experienced rapid and severe host population decline. The results of the simulation suggest that a social network size of between 180 and 440 persons is required under the conditions of this model for host-pathogen coexistence (i.e., endemicity) to occur. The severe population decline experienced by these populations suggests that tuberculosis as modeled here could not have existed in these populations. Future refinements of modeling and simulation techniques can provide additional insights into how disease spreads among social contacts.

Quantitative genetics of cranial nonmetric traits in randombred mice: heritability and etiology

Cheverud and Buikstra (1981) demonstrated a tendency for nonmetric traits representing the number of foramina to have lower heritabilities than those representing hyperstotic or hypostotic traits in a sample of rhesus macaques. Based on this observation, Cheverud and Buikstra hypothesize that differences in the heritability of the two sets of traits may be due to differences in trait etiology. This study addresses the proposed relationship between trait heritability and etiology. Heritability values are calculated for 35 cranial nonmetric traits in a sample of 320 randombred mice using analysis of variance. The results are minimally consistent with the etiological hypothesis, but only 4 of the 35 traits showed statistically significant heritability values. These results are discussed with reference to the assumption that nonmetric traits have a strong genetic component. It is concluded that the developmental pathways that genetic variation traverses before being expressed in the form of nonmetric traits must be understood before variation in nonmetric traits can be used to its fullest potential.

Genetic correlations between sides and heritability of asymmetry for nonmetric traits in rhesus macaques on Cayo Santiago

The use of nonmetric traits for estimation of biological distance is a long-standing practice in biological anthropology. Nonmetric traits can be scored using either the individual or the side of the individual as the unit of measure. If sides of the individual are genetically correlated the use of sides would produce redundant genetic information. For this reason, Korey (Am. J. Phys. Anthropol. 53:19-23, 1980) argues for the use of individuals as the unit of measure for nonmetric traits. Ossenberg (Am. J. Phys, Anthropol. 54:471-479, 1981), however, argues that bilateral occurrence of nonmetric traits indicates greater genetic liability for the trait and that therefore the sides are the more biologically correct unit of measure. Genetic correlations for 13 cranial nonmetric traits are estimated for a sample of rhesus macaque skeletons from Cayo Santiago. In addition, heritability of asymmetry is estimated for these 13 traits as a test of Ossenberg's contention that asymmetry is genetically influenced. Significant genetic correlations between sides support Korey's contention that nonmetric traits should be scored by individual. Only two asymmetry heritabilities were significantly different from zero, providing no significant support for Ossenberg's contention that asymmetry is genetically determined. Our results support the theory that asymmetry represents a measure of the ability of an organism to buffer stresses. Therefore, a measure of the heritability of asymmetry is a measure of the heritability of the ability to buffer stresses. This ability does not appear to be heritable in this sample.