Mueller matrix of the particle-free atmospheric enhanced backscatter.

The spatially resolved Mueller matrix of a mono-static optical system with the corner-cube retro-reflector operating in the presence of clear-air atmospheric turbulence is measured for the first time, to the best of our knowledge. The changes in the polarization properties of the beam are caused by the combination of deterministic polarimetric modulation by the retro-reflector and random scalar modulation of the return beam by atmospheric turbulence. In particular, the spatial structure of the Mueller matrix within the enhanced backscatter area is revealed.

Effect of dilution rate and nutrients addition on the fermentative capability and synthesis of aromatic compounds of two indigenous strains of Saccharomyces cerevisiae in continuous cultures fed with Agave tequilana juice.

Knowledge of physiological behavior of indigenous tequila yeast used in fermentation process is still limited. Yeasts have significant impact on the productivity fermentation process as well as the sensorial characteristics of the alcoholic beverage. For these reasons a better knowledge of the physiological and metabolic features of these yeasts is required. The effects of dilution rate, nitrogen and phosphorus source addition and micro-aeration on growth, fermentation and synthesis of volatile compounds of two native Saccharomyces cerevisiae strains, cultured in continuous fed with Agave tequilana juice were studied. For S1 and S2 strains, maximal concentrations of biomass, ethanol, consumed sugars, alcohols and esters were obtained at 0.04 h⁻¹. Those concentrations quickly decreased as D increased. For S. cerevisiae S1 cultures (at D=0.08 h⁻¹) supplemented with ammonium phosphate (AP) from 1 to 4 g/L, concentrations of residual sugars decreased from 29.42 to 17.60 g/L and ethanol increased from 29.63 to 40.08 g/L, respectively. The S1 culture supplemented with AP was then micro-aerated from 0 to 0.02 vvm, improving all the kinetics parameters: biomass, ethanol and glycerol concentrations increased from 5.66, 40.08 and 3.11 g/L to 8.04, 45.91 and 4.88 g/L; residual sugars decreased from 17.67 g/L to 4.48 g/L; and rates of productions of biomass and ethanol, and consumption of sugars increased from 0.45, 3.21 and 7.33 g/L·h to 0.64, 3.67 and 8.38 g/L·h, respectively. Concentrations of volatile compounds were also influenced by the micro-aeration rate. Ester and alcohol concentrations were higher, in none aerated and in aerated cultures respectively.

Physicians' opinions about partner notification methods: case reporting, patient referral, and provider referral.

BACKGROUND: The United States has relied upon partner notification strategies to help break the chain of infection and re-infection for sexually transmitted diseases (STD). Physicians are a vital link in the system of STD control, but little is known of physician opinions about partner notification strategies. METHODS: We collected opinions about partner notification from a national probability sample of physicians in specialties diagnosing STDs. Physicians responded to 17 questions about three relevant forms of STD partner notification: patient based referral, provider based referral, and case reporting. RESULTS: Exploratory factor analyses showed that responses for each form of partner notification could be grouped into four categories: perceived practice norms, infection control, patient relationships, and time/money. Multivariate analyses of the factors showed that physicians endorsed patient based referral most favourably and provider based referral least favourably. CONCLUSION: Physicians' opinions about partner notification strategies appear to reflect objective reality in some areas, but not in others. Strategies that improve the fit between physicians' opinions and effective notification are needed: some are discussed here.

The effects of variations in mode of delivery and monetary incentive on physicians' responses to a mailed survey assessing STD practice patterns.

High response rates from physicians are key to obtaining valid and generalizable data regarding their sexually transmitted disease (STD) diagnosis, treatment, and control practices. A factorial (3 x 2) study was designed using varying cash incentives ($0, $15, $25) and delivery modes (Federal Express, U.S. mail). Surveys, with three follow-up mailings, were sent to a national probability sample of 311 physicians in OB-GYN, family practice, internal and emergency medicine, and pediatrics specialties. Overall, 156 physicians returned completed surveys (56% overall response rate). Significant effects for incentive level (F = 28.2, df = 2, p < .01) and delivery mode (F = 4.1, df = 1, p < .05) existed. Highest response was among physicians in the $25-FedEx condition (81%). High response rates from busy practicing physicians can be achieved if surveys are relevant to clinical practice, sponsored by a reputable organization (the Centers for Disease Control and Prevention), include a monetary incentive, and are delivered by courier.

Prostitution and the sex discrepancy in reported number of sexual partners.

One of the most reliable and perplexing findings from surveys of sexual behavior is that men report substantially more sexual partners than women do. We use data from national sex surveys and studies of prostitutes and their clients in the United States to examine sampling bias as an explanation for this disparity. We find that prostitute women are underrepresented in the national surveys. Once their undersampling and very high numbers of sexual partners are factored in, the discrepancy disappears. Prostitution's role in the discrepancy is not readily apparent because men are reluctant to acknowledge that their reported partners include prostitutes.

Explaining physician rates of providing flexible sigmoidoscopy.

Colorectal cancer is the third most frequent cancer, yet screening rates for this cancer remain low. This study was designed to identify factors associated with family physicians' rates of recommending or providing flexible sigmoidoscopy. We applied a behavioral model consisting of three components: physician attitude toward providing the test, facilitating conditions, and reinforcing conditions. Qualitative interviews identified relevant measures of each model component and guided the design of the survey. The survey was administered to 60 randomly selected family physicians in Washington State. Chart reviews were conducted to measure physician rates of providing flexible sigmoidoscopy. All three model components were significantly correlated with sigmoidoscopy rate. Multiple regression found physician attitude, facilitating conditions, and their interaction to be significant determinants of sigmoidoscopy rate (multiple R = 0.72). Analyses of specific items used to measure physician attitude found that physician beliefs about cost, time, income, degree of distaste, risk of complications, and screening effectiveness were significantly correlated with sigmoidoscopy rate. Specific facilitating conditions found to be correlated with rate of providing the test included physician and staff training, availability of a reminder system, and clinic structural conditions. This study provides strong support for application of a theory-based model to understand physician provision of flexible sigmoidoscopy testing for colorectal cancer. The findings provide very specific information to guide development of educational and motivational efforts and modification of facilitating conditions to increase physician provision of sigmoidoscopy to control colorectal cancer.

Acting on one's intentions: Variations in condom use intentions and behaviours as a function of type of partner, gender, ethnicity and risk.

People may not take protective action (e.g. use condoms) either because they have no intention to engage in the protective behaviour, or because they have the appropriate intention but are unable to act upon it. This paper examines variations in intentions to use condoms for vaginal intercourse with main and casual partners as a function of gender, ethnicity and risk. Additionally, the paper examines the extent to which these different factors influence the degree to which people can (or cannot) act upon their intentions. While 68% of men and 81% of women report intentions to use condoms for vaginal sex with their casual partners, only 33% of men and 37% of women intend to use condoms for vaginal sex with their main partner. Men with positive intentions were able to carry out those intentions about 64% of the time with respect to both main and casual partners; women with positive intentions were able to act upon these intentions 53% of the time with their main partners, but almost 82%, of the time with their casual partners. Possible factors influencing the ability to act on one's intentions are explored and implications for interventions are discussed.

A clinic-based mammography intervention targeting inner-city women.

OBJECTIVE: The objective was to evaluate the effect of a clinic-based intervention program on mammography use by inner-city women. DESIGN: A randomized controlled trial employing firm system methodology was conducted. SETTING: The study setting was a general internal medicine clinic in the university-affiliated county hospital serving metropolitan Seattle. PARTICIPANTS: Women aged 50 to 74 years with at least one routine clinic appointment (when they were due for mammography) during the study period were enrolled in the trial (n = 314). INTERVENTIONS: The intervention program emphasized nursing involvement and included physician education, provider prompts, use of audiovisual and printed patient education materials, transportation assistance in the form of bus passes, preappointment telephone or postcard reminders, and rescheduling assistance. Control firm women received usual care. MEASUREMENTS AND MAIN RESULTS: Mammography completion within 8 weeks of clinic visits was significantly higher among intervention (49%) than control (22%) firm women (p < .001). These effects persisted after adjustment for potential confounding by age, race, medical insurance coverage, and previous mammography experience at the hospital (odds ratio 3.5; 95% confidence interval 1.9, 6.5). The intervention effect was modified by type of insurance coverage as well as prior mammography history. Process evaluation indicated that bus passes and rescheduling efforts did not contribute to the observed increases in screening participation. CONCLUSIONS: A clinic-based program incorporating physician education, provider prompts, patient education materials, and appointment reminders and emphasizing nursing involvement can facilitate adherence to breast cancer screening guidelines among inner-city women.

Mammography use among women attending an inner-city clinic.

BACKGROUND: Low-income, minority, and inner city women have breast cancer screening rates that are below those of the general population. METHODS: The authors surveyed women who received primary care at Seattle's county hospital about their mammography behaviors in early 1995. Data were analyzed within the context of the PRECEDE framework. RESULTS: Only half (48%) of the women were obtaining regular screening. Breast cancer and mammography beliefs differed by racial group. The following factors differentiated between inner-city women who were and were not regular users: mammography beliefs concerning early detection of disease, pressure from the machine causing breast cancer, and cost (these were less important among white women than members of other racial groups); previous physician discussions, concerns about appointment scheduling, and transportation problems; and social support from physicians, family, and friends. CONCLUSION: Interventions to encourage regular screening among inner-city women should address predisposing, enabling, and reinforcing factors.

Understanding mammography intention and utilization among women in an inner city public hospital clinic.

BACKGROUND: Most research on mammography utilization has been conducted among middle-class women. There is a need for research to identify factors affecting mammography utilization among low-income women to develop effective interventions for this underserved subgroup. METHODS: An expanded theory of reasoned action guided this research among low-income inner-city women who use a public hospital. Qualitative interviews were conducted to develop a questionnaire with items relevant to this population. The questionnaire included 5 affect measures, 13 behavioral beliefs, 5 sources of influence, and 6 facilitator/constraint measures. The survey was mailed to 584 women ages 50 to 69 identified through the hospital database. RESULTS: After those ineligible and undeliverable were excluded, responses rates were obtained from 361 women (84% adjusted response rate). Sixty-six percent had a mammogram within the previous year and 58% were very sure that they would get a mammogram in the next year. Affect, attitude, subjective norm, and facilitator scores were computed. All four constructs had significant correlations (r = 0.38 to 0.41) with intention to get a mammogram in the next year and all had significant multiple regression weights (R = 0.54). All but three items making up the model components were significantly correlated with screening intention. CONCLUSIONS: The data from applying a behavioral model indicate that intervention efforts to increase mammography utilization among low-income women should target all four model components. A clinic-based intervention could use multiple methods to deliver messages developed to target each of the model component items found to be associated with mammography intention.

Attitudes and beliefs toward mammography among women using an urban public hospital.

Although overall use of mammography is steadily increasing, low-income and minority women consistently have relatively lower screening rates than white, middle-class women. To assess the mammography-seeking behavior of low-income women using an urban public hospital, this study sought to understand why women in this population decide whether or not to obtain a screening mammogram. Two qualitative techniques, elicitation interviews and focus groups, were used to develop an understanding of attitudes, concerns, and barriers of this group relative to mammography. Fear, embarrassment, susceptibility to breast cancer, inconvenience, cost, concerns about efficacy of mammography, fear of acquiring cancer, and scheduling difficulties were identified as important concerns. "People in the news" were the most influential social referents for mammography decision making, followed by physicians, family members, and friends. The insights gained from these women will assist in developing interventions that encourage mammography-seeking behavior by low-income women.

Community organization to promote breast cancer screening among women ages 50-75.

BACKGROUND: To reduce breast cancer mortality, ways to promote the use of mammography screening among women age 50 and above are needed. Community organization may be a useful approach. METHODS: The Washington State Community Breast Cancer Screening Project involved implementation of promotional activities initiated by physician and lay community boards in two communities. Two comparable communities served as controls for evaluation purposes. Random-digit-dial telephone interviews were used to assess recent use of mammography at baseline and follow-up in independent samples of women ages 50 to 75 from the four communities. The extent of exposure to intervention activities and the relationship between exposure to intervention activities and mammography use were estimated from data collected at follow-up. RESULTS: Exposure to patient reminders from physicians, wallet reminder cards, and newspaper advertisements were consistently related to mammography use. Physician office staff encouragement and a display board were significantly related to mammography use only in Intervention Communities A and B, respectively. Neither exposure to promotional activities nor the change in prevalence of mammography use was significantly higher in the intervention communities than in the comparison communities at follow-up. CONCLUSIONS: Although several activities were useful in promoting mammography use, organization of the community did not enhance efforts undertaken spontaneously by comparable communities.

Cancer screening by primary care physicians: a comparison of rates obtained from physician self-report, patient survey, and chart audit.

OBJECTIVES: This study measured the cancer screening rates of family physicians and compared the measures obtained through physician self-reports, chart audits, and patient surveys. METHODS: A cancer screening survey was sent to 50% of the members of the Washington Academy of Family Physicians, with 326 family physicians (74% response rate) completing the survey. Sixty physicians were recruited for the patient survey and chart audit phase, with a 90% participation rate. Patient surveys were conducted with about 350 patients per physician, and chart audits were conducted on a subset of about 50 patients per physician. Each physician's rate of providing each service was computed from the self-report, the patient survey, and the chart audit. RESULTS: Physicians provided many of these services at rates different from those commonly recommended. Large discrepancies were found between the rates measured by different methods. Correlations between rates derived from chart audits and patient surveys were high; however, correlations between rates from physician self-report and either patient survey or chart audit were much lower for all services. CONCLUSIONS: Studies of physicians' provision of cancer prevention services should not rely on physician self-report, but should obtain the rates through patient surveys or chart audits.

Specialty differences and the ordering of screening mammography by primary care physicians.

BACKGROUND: Careful attention to factors that affect women and their physicians is necessary to achieve the national goal that, by the year 2000, 60 percent of women should have had a screening mammogram in the previous 2 years. This report evaluates factors that differentiate primary care physicians who regularly order mammograms from those who do not. The study was conducted as part of a large demonstration project in Washington State and includes a survey of women served by the physicians. METHODS: We conducted a survey of primary care physicians and women in four counties to assess factors that influenced self-reported ordering of screening mammography. RESULTS: Among the 73 percent of family physicians, general practitioners, internists, and obstetrician-gynecologists who returned the questionnaire, there were more obstetrician-gynecologists (76 percent) who reported ordering screening mammograms in 90 percent or more of women aged 50 to 75 years, but they cared for only 15 percent of women in the sample. Women's survey results confirmed the physicians' reported differences and also revealed demographic characteristics that distinguished populations associated with particular primary care specialists. These specialists differed in their perceptions of their colleague's mammography practices, the adequacy of insurance coverage, and how often they had spent an unreasonable time explaining mammography results. In a multivariate model of factors expected to influence behavior, performance of clinical breast examination rather than specialty was the salient factor associated with ordering screening mammography. CONCLUSIONS: These results suggest that the context of practice, rather than specialty type or beliefs about mammography, has the major influence upon behavior. To achieve national screening mammography goals in the Northwest, we must influence the context of family physicians' preventive care practices because they care for 47 percent of women aged 50 years or older.

Using physician correspondence and postcard reminders to promote mammography use.

OBJECTIVES: In a health maintenance organization that mails letters to women recommending that they schedule mammograms, we conducted a randomized trial to evaluate simple methods of increasing the use of screening mammography. METHODS: Using a 2 x 2 factorial design, we tested the effects of (1) mailing the recommendation letter from each woman's primary care physician rather than from the program director and (2) sending a subsequent reminder postcard. RESULTS: Sending a reminder postcard nearly doubled the odds that women would get mammograms within 1 year (participate). The letter from the woman's personal physician had no effect. Attending a clinic more than 45 minutes from the screening center, being a current smoker, or being in fair or poor health were negatively associated with subsequently obtaining a mammogram. The odds of participation doubled if women had had previous mammograms. CONCLUSIONS: When preceded by written recommendations to schedule mammograms, reminder postcards effectively increased participation. Future randomized trials to promote use of screening mammography should compare interventions with a reminder condition.

Use of screening mammography by general internists.

While physician endorsement has been shown to be highly important in motivating women to obtain screening mammograms, there is evidence that doctors do not refer women for the procedure as often as they should. The objective of this study was to help understand why physicians do not routinely utilize screening mammography. Randomly selected Washington State general internists were surveyed by mail, concerning mammography, during 1989. An expanded theory of reasoned action was used as a broad conceptual framework for considering factors potentially associated with use. The survey response rate was 66%, yielding a study sample of 85. Only 38% of the respondents reported they always ordered mammograms for women aged 50 years and over during preventive office visits. Nearly half (43%) had no reminder system for the test. Correlates of use included beliefs concerning the screening behavior of other doctors, the location of mammography facilities in relation to physician offices, and age. Physician-related barriers, such as doubts about effectiveness, were found to affect use more than patient-related barriers, such as cost. The recommendations of professional organizations were shown to have been important in influencing physician use of screening mammography. This study indicates a proportion of general internists are not routinely ordering mammograms for their age-eligible female patients. The findings identify barriers to use of mammography that need to be overcome if national efforts to promote use of the procedure by primary care physicians are to succeed. Implications for intervention are reviewed.

Attitudes, age, and participation in mammographic screening: a prospective analysis.

BACKGROUND: To address the needs of older women, we investigated age-specific attitudes toward mammography that might be influenced by written or verbal communications. METHODS: Attitudinal scores for women aged 40 through 64 years and 65 years and older were calculated prospectively from responses to a mailed questionnaire based on the theory of reasoned action. Age-group mean scores were compared using t-tests for eight components of the attitude measure. Score correlations with participation were compared between age groups using multivariate analysis. RESULTS: Of the 919 eligible women, 666 (72 percent) completed the study questionnaire, and 433 (65 percent) of the 666 women obtained mammograms. A woman aged 65 years or older was less likely to believe that mammography could find a cancer that she (P < 0.01) or her physician (P < 0.05) could not find, and she valued this characteristic less than a younger woman in each instance (P < 0.01). The belief that mammography involved asymptomatic detection was more highly correlated with participation in older women (P < 0.05), as was the attitude that mammography was unfamiliar, but acceptable (P < 0.05). CONCLUSIONS: Older women are less likely to understand that mammography can find cancers that might be missed by other screening methods. Communications to encourage mammography among older women should explain its strengths and familiarize them with the procedure. Communications to younger women need to consider other factors.

A test of an expanded theory of reasoned action to predict mammography participation.

This paper presents the results of a prospective study testing an expanded theory of reasoned action (TRA) to predict mammography participation. A questionnaire was developed to measure each of the expanded TRA model components. A sample was identified of 946 women age 40 and above who were invited to obtain a mammogram at the Group Health Cooperative of Puget Sound Breast Cancer Screening Program (BCSP). The sample was stratified by risk category as determined by the screening program. The study questionnaire was administered to all women in the sample within 2 weeks after they were sent the invitation to obtain a mammogram. Mammography participation was obtained from the BCSP data base 6 months after the invitation. Regression analyses found attitude, affect, subjective norm, and facilitating conditions to all be significantly associated with participation. The expanded TRA model explained 39% of the variance in women's intentions and 20% of the variance in participation behavior. A stepwise hierarchical regression found that no other psychosocial measures were able to improve the model predictions of behavior. An interaction between habit and intention was found such that women with larger numbers of previous mammograms were less likely to carry out their intentions than women with fewer previous mammograms. Contrary to expectations, some demographic characteristics did significantly improve prediction. The need for further work investigating the roles of fear and experience is discussed.

A survey of the attitudes of physician specialists toward capitation-based health plans with primary care gatekeepers.

A survey of 414 Washington state physicians board certified in one of seven non-primary care specialties (gastroenterology, cardiology, dermatology, otolaryngology, orthopedics, psychiatry, and general surgery) assessed physician attitudes towards capitation-based health plans with primary care gatekeepers. Responses indicated significant differences in attitude according to specialty. Negative attitudes were more prevalent among physicians in solo practices and those practicing in smaller communities and were related to quality of care provided, lack of information regarding benefits, loss of physician autonomy, and heavy administrative demands in these plans. Although most respondents disapproved of capitation-based health plans, a significant number agreed that gatekeeper-based plans serve to increase public awareness about health care costs as well as to control health care costs.