Compression-induced crossovers for the ground state of classical dipole lattices on a Möbius strip.

We explore the ground-state properties of a lattice of classical dipoles spanned on the surface of a Möbius strip. The dipole equilibrium configurations depend significantly on the geometrical parameters of the Möbius strip, as well as on the lattice dimensions. As a result of the variable dipole spacing on the curved surface of the Möbius strip, the ground state can consist of multiple domains with different dipole orientations which are separated by domain-wall-like boundaries. We analyze in particular the dependence of the ground-state dipole configuration on the width of the Möbius strip and highlight two crossovers in the ground state that can be correspondingly tuned. A first crossover changes the dipole lattice from a phase which resists compression to a phase that favors it. The second crossover leads to an exchange of the topological properties of the two involved domains. We conclude with a brief summary and an outlook on more complex topologically intricate surfaces.

Driven toroidal helix as a generalization of the Kapitza pendulum.

We explore a model system consisting of a particle confined to move along a toroidal helix while being exposed to a static potential as well as a driving force due to a harmonically oscillating electric field. It is shown that in the limit of a vanishing helix radius, the governing equations of motion coincide with those of the well-known Kapitza pendulum-a classical pendulum with oscillating pivot-implying that the driven toroidal helix represents a corresponding generalization. It is shown that the two dominant static fixed points present in the Kapitza pendulum are also present for a finite helix radius. The dependence of the stability of these two fixed points on the helix radius, the driving amplitude, and the static potential are analyzed analytically. These analytical results are subsequently compared to results corresponding of numerical simulations. Additionally, the most prominent deviations of the driven helix from the Kapitza pendulum with respect to the resulting phase space are investigated and analyzed in some detail. These effects include an unusual transition to chaos and an effective directed transport due to the simultaneous presence of multiple chaotic phase space regions.

Legislative view of research.

Congress has its own perception of research; whether it equates to reality is up to the research community. Many in Congress perceive that the research community is free-floating and is not focused on addressing the problems that face the United States today. Recent government reports have reviewed the purposes, accountability, and challenges facing the traditional research and extension system as it enters the 1990s. These reports send a strong message that the status quo will not work sufficiently in the 1990s. How does this affect agricultural research dollars? Congress, in response to its own perceptions, has strived to establish priorities by allocating resources to key projects. Whether this is in the best interest of the nation is debatable. The agricultural research community needs to establish priorities and to communicate them effectively; otherwise someone less informed in the Congress will do it.

Yearling adjustments for pelvic area of test station bulls.

Yearling bulls (n = 3,071) located at 18 stations in Missouri, Nebraska, Virginia, and Wisconsin were measured for pelvic area, in addition to standard performance traits. Linear adjustments for age and weight were determined using covariate regression analyses. Only bulls that were 300 to 452 d of age, 325 to 640 kg, and were in consignments offering more than nine bulls per breed were included in the analyses. Because the subsets of Angus, Polled Hereford, and Simmental bulls had large numbers of observations (817, 271, and 449, respectively), individual adjustment coefficients were determined for each breed. Angus, Polled Hereford, and Simmental bulls had pelvic area adjustment regressions on age of .20, .32, and .20 cm2/d, respectively, and regressions on body weight of .15, .22, and .18 cm2/kg, respectively. Homogeneous linear responses of all breeds (11 breeds including Angus, Polled Hereford, and Simmental) were combined to form all-breed coefficients for age and weight adjustments, which were .21 cm2/d and .15 cm2/kg, respectively. Weight or age adjustments can be used to compare contemporaries for relative pelvic area differences, but both should not be used on the same bull. Although many factors contribute to dystocia, high priority should be given to identifying sires of replacement heifers of low to moderate birth weight genotype and above average pelvic area genotype.

Composition of pork carcasses by potassium-40 liquid scintillation detection: estimation and validation.

Liquid scintillation detection of potassium-40 was used to estimate pork carcass composition of 124 boars, barrows and gilts. Pigs were fed to five live weights (23, 45, 68, 91 and 114 kg) and 40K emissions were determined on live pigs in a whole body counter (WBC) equipped with a two-pi liquid scintillation detector. Then, pigs were slaughtered conventionally and the right side of each carcass was weighed, 40K emissions of this carcass side was determined in the WBC and total grams of potassium were calculated. The right side of each carcass was ground, sampled and analyzed for fat, protein, moisture and potassium. Fat, protein, moisture and overall potassium percentage means were 23.9 +/- 7.2, 16.5 +/- .94, 57.0 +/- 6.5 and .25 +/- .02, respectively. Whole body counter carcass potassium was highly correlated (P less than .01) to chemically determined carcass potassium (r = .70). Percentage of fat, protein and moisture prediction equations were formed by stepwise regression using the linear, quadratic and interactive effects of live animal and carcass side weight. Whole body counter live animal and carcass potassium and sex were utilized as independent variables. Carcass weight and 40K determined potassium of the carcass explained more of the variation in carcass composition than did live animal weight and 40K determined potassium of the live animal.

Vasectomy and cardiovascular deaths in Korean men: a community-based case-control study.

This community-based case-control study was carried out in four cities in South Korea to examine whether vasectomy is associated with a long-term increased risk of cardiovascular death in Korean men. Our results coincide with those from epidemiological studies conducted in Western countries as well as the one study conducted in China and do not support the vasectomy--atherosclerosis hypothesis originating from animal research.

PIP: Researchers compared data on 413 35-65 year old men who died between October 1982-September 1983 with data on 413 healthy 35-65 year old men. Both cases and controls were from Seoul, Pusan, or Incheon, South Korea. Interviewers spoke only to wives as proxies of the deceased. 36 cases and 26 controls had undergone a vasectomy, but none of their counterparts had undergone a vasectomy. This paired analysis revealed a statistically nonsignificant odds ratio (OR) of 1.38. The researchers then controlled for all confounding variables while conducting a multivariate analysis. They found the adjusted OR to be 1 for vasectomy. None of the 3 underlying causes of death ORs (cerebrovascular disease, ischemic heart disease, and hypertensive disease) different significantly from unity. The leading cause of death was stroke (71.4%). Just 7% died from ischemic heart disease. Limitations of the study included problematic diagnosis of underlying causes of death, heterogeneous cardiovascular deaths, and the lack of distinction between thrombotic or hemorrhagic stroke, and small number of cases when stratified by length of exposure to vasectomy or by cause of death. Nevertheless, like other epidemiologic studies, this community-based study did not find an association between cardiovascular deaths and vasectomy, even though animal research in the late 1970s-early 1980s found that vasectomy in monkeys brought on a progression of atherosclerosis.

Comparison of market hog characteristics of pigs selected by feeder pig frame size or current USDA feeder pig grade standards.

Two feeder pig grading systems were tested. Forty-five barrows were selected using current USDA Feeder Pig Grade Standards (U.S. No. 1, No. 2 and No. 3). Additionally, 45 barrows were selected using three frame sizes (large, medium and small). Pigs were slaughtered at 100, 113.5 of 127 kg live weight. Trimmed four lean cuts were separated into soft tissue, skin and bone. The skinless belly and soft tissue from the four lean cuts were ground separately and analyzed chemically. Data from each grading system were analyzed separately in a 3 X 3 factorial plan. Pigs selected using current USDA grade standards differed (P less than .05) for last rib backfat, 10th rib fat depth, longissimus muscle area, percentage of trimmed four lean cuts and USDA carcass grade. In the frame size system, pigs with large frame size had less last rib backfat, less 10th rib fat depth, longer carcasses, higher percentage of four lean cuts and superior USDA carcass grades than pigs with small frame size did (P less than .05). The Bradley and Schumann test of sensitivity showed that selection by frame size was more sensitive than current USDA grade standards for discriminating feeder pig foreleg length, body depth and ham width. In addition, selection by frame size was more sensitive than current USDA grade standards for discriminating carcass length and carcass radius length. No increase in sensitivity (P greater than .10) was noted for carcass composition or growth traits over the current USDA Feeder Pig Grade Standards.

Evidence for a cultivar and a chronology from patterned wetlands in central veracruz, Mexico.

The patterning found in certain wetlands of lowland Mesoamerica has added an important element to the subsistence system that may be attributed to pre-Hispanic inhabitants of the region. The form of the remains, largely expressed in terms of surface vegetation, suggests agriculture on planting platforms, separated by canals. The physical and chemical aspects of the stratigraphy have clarified depositional environments but have not indicated agricultural horizons. Maize phytoliths at about 1 meter below the surface in two Central Veracruzan wetlands do confirm the practice of agriculture. Associated ceramics indicate wetlands agriculture was practiced by A.D. 500 and perhaps earlier.

Rare events occurring at insertion of an intrauterine device--a review of an international experience.

Events occurring at the time of insertion of an intrauterine device (IUD) are rarely studied, especially for parous women for whom, in theory, IUD contraception is most suitable. These events, although rare, cause personal distress, embarrassment and inconvenience and can have a negative impact on IUD acceptance. Sixty million women worldwide are using IUDs. Thus, even a rare event may have important public health implications. To avoid such occurrences, the risk factors of these rare events need to be delineated. The large international IUD data set compiled by Family Health International (FHI) since 1972 provides a unique opportunity to achieve this purpose. Four IUD insertion-related rare events have been studied, namely: insertion failure, uterine perforation, syncope and other vasovagal reactions, and severe insertional pain. This review paper summarizes the important findings from these as well as other relevant studies. This broad experience should form the basis by which health personnel inserting IUDs can improve the quality of care for women requesting a device for contraception.

Pregnancy following minilaparotomy tubal sterilization--an update of an international data set.

Seventeen pregnancies were reported from an international tubal sterilization data set comprising 1,862 minilaparotomy cases between 1978 and 1984. Of these 17, seven (41.2%) were diagnosed as luteal phase pregnancies. Of the 10 pregnancies due to sterilization failure, one was an ectopic pregnancy which occurred much later (20 months poststerilization) than the intrauterine pregnancies (10 months or less). Poststerilization pregnancy risk was greater among gravid women (those undergoing sterilization at the time of abortion or soon after childbirth) than among non-gravid women (those undergoing interval sterilization). These findings are, in general, consistent with those of previous studies using a much larger data set of primarily laparoscopic sterilizations. Pregnancies occurred with every type of mechanical tubal occlusion techniques included for study (the tubal ring, the Rocket Clip, the Secuclip and the Filshie Clip), and a frequently reported reason for failure was incorrect placement of the device. No pregnancies occurred in women sterilized with the non-mechanical Pomeroy/modified Pomeroy techniques. Findings of this analysis suggest that in minilaparotomy sterilization, for the mechanical tubal occlusion techniques to be as effective as the Pomeroy/modified Pomeroy techniques, more care and skill are required for the operator.

PIP: 17 pregnancies were reported from an international tubal sterilization data set comprising 1,862 minilaparotomy cases between 1978 and 1984. Of these 17, 7 (41.2%) were diagnosed as luteal phase pregnancies. Of the 10 pregnancies due to sterilization failure, 1 was an ectopic pregnancy which occurred much later (20 months poststerilization) than the intrauterine pregnancies (10 months or less). Poststerilization pregnancy risk was greater among gravid women (those undergoing sterilization at the time of abortion or soon after childbirth) than among non-gravid women (those undergoing interval sterilization). These findings are, in general, consistent with those of previous studies using a much larger data set of primarily laparascopic sterilizations. Pregnancies occurred with every type of mechanical tubal occlusion technic included for study (the tubal ring; the Rocket Clip; the Secuclip; and the Filshie Clip), and a frequently reported reason for failure was incorrect placement of the device. No pregnancies occurred in women sterilized with the non-mechanical Pomeroy/modified Pomeroy technics. Findings of this analysis suggest that in minilaparotomy sterilization, for the mechanical tubal occlusion technics to be as effective as the Pomeroy/modified Pomeroy technics, more care and skill are required for the operation.

A clinical trial of Neo Sampoon vaginal tablets and Emko foam in Alexandria, Egypt.

Results are reported for a comparative 12-month study of Neo Sampoon foaming vaginal tablets containing 60 mg of the spermicide, menfegol, and Emko vaginal foam containing an 8.0% concentration of the spermicide, nonoxynol-9. Conducted in cooperation with the Family Planning Association in Alexandria, Egypt, the trial included 349 women who were randomly allocated to use one of the two contraceptive products. The twelve-month cumulative life-table rate for accidental pregnancy (per 100 women) was 2.8 for Neo Sampoon tablet users and 2.1 for Emko foam users. The 12-month continuation rates were 77.6 and 77.2 per 100 women for the tablet and foam groups, respectively. In both groups, the majority of discontinuations from the study were for personal reasons, including lack of confidence in the method, messiness, partner's objection and a burning sensation. Few women reported a product-related complaint while using their assigned contraceptive method. The most commonly reported complaint for both methods was that use of the product led to an uncomfortable burning sensation for the woman and/or her partner. This complaint, however, was cited by less than 5% of the women in each group. Thus, a combination of low pregnancy rates, few complications and complaints and high continuation rates confirm the relative acceptability, effectiveness and short-term safety of these methods of contraception among this sample of Egyptian women.

PIP: Results are reported for a 12-month study of Neo Sampoon foaming vaginal tablets containing 60mg of the spermicide, menfegol, and EMKO vaginal foam containing an 8.0% concentration of the spermicide, nonoxynol-9. Conducted in cooperation with the Family Planning Association in Alexandria, Egypt, the trial included 349 women randomly allocated to use 1 of 2 contraceptive products. The 12-month cumulative life-table rate for accidental pregnancy (per 100 women) was 2.8 for Neo Sampoon tablet users and 2.1 for Emko foam users. The 12-month continuation rates were 77.6 and 77.2/100 women for the tablet and foam groups, respectively. In both the majority of discontinuations from the study were for personal reasons, including lack of confidence in the method, messiness, partner's objection and a burning sensation. Few women reported a product-related complaint while using their assigned contraceptive method. The most commonly reported complaint for both methods was that use of the product led to an uncomfortable burning sensation for the woman and/or her partner. This complaint, however, was cited by 5% of the women in each group. Thus, a combination of low pregnancy rates, few complications and complaints and high continuation rates confirm the relative acceptability, effectiveness and short-term safety of these methods of contraception among this sample of Egyptian women.

[Vasectomy and cardiovascular deaths in Korean men].

PIP: This community-based case-control study was carried out in 4 cities in South Korea to investigate whether vasectomy is associated with a long-term increased risk of cardiovascular death. The cases are 413 men who died at ages 35-65 between October 1982 and September 1983 with an underlying cause of death, as reported in the death certificate, of ischemic heart disease (29 men), nontraumatic cerebrovascular disease (295 men), or hypertensive disease (89 men). Each case was matched for age and parity to a living male from the same neighborhood. Wives of cases and controls were interviewed at home as surrogates. Univariate analysis of the association between vasectomy and cardiovascular death revealed an odds ration of 1.4. Multivariate logistic regression analysis, controlling for potentially confounding variables, revealed a lower adjusted odds ratio of 1. The authors did not detect an association between vasectomy and cardiovascular death in Korean men; nor did they find a statistically significant increased risk for those subjects who had a vasectomy 15 years or more previously. These results concur with those from Western epidemiologic studies and do not support the vasectomy-atherosclerosis hypothesis originating from animal research.^ieng

Severe pain at interval IUD insertion: a case-control analysis of patient risk factors.

This investigation, using a case-control analysis approach on an IUD data set from a less-developed country center, delineated four risk factors in patient characteristics that are associated with severe pain at interval IUD insertion. They are: higher education (greater than or equal to seven years), low-parity (1-2 live births), longer open interval (greater than or equal to 13 months) between the end of the last pregnancy and insertion, and non-breastfeeding at the time of insertion. Adjusted relative risks estimated by odds ratios are 2.1, 2.7, 2.7 and 5.0, respectively. For women with a combination of the above risk factors, they have a further increased (additive in nature) risk of suffering severe insertion pain. Similar analysis was also performed on a developed country center data set for which only the effect of education and parity could be studied; an odds ratio of 5.0 for nulliparity was obtained. The plausibility of these findings as well as their clinical and programmatic implications are discussed.

PIP: This investigation, using a case-control analysis approach on an intrauterine device (IUD) data set from a less-developed country center, delineated 4 risk factors in patient characteristics that are associated with severe pain at interval IUD insertion. They are: higher education ( or = 7 years) low parity (1-2 live births), longer open interval ( or = 13 months) between the end of the last pregnancy and insertion, and non-breast feeding at the time of insertion. Adjusted relative risks estimated by odds ratios are 2.1, 2.7, 2.7, and 5.0 respectively. For women with a combination of the above risk factors, they have a further increased (additive in nature) risk of suffering severe insertion pain. Similar analysis was also performed on a developed country center data set for which only the effect of education and parity could be studied; an odds ratio of 5.0 for nulliparity was obtained. Better educated women are probably less inhibited to complain of pain than less-educated women. A tighter uterine cervix and a smaller uterine cavity in women of low parity may account for IUD insertion pain. Postpartum involution of the uterus could explain pain upon insertion for women with a long open interval. These findings support the hypothesis that cervical stretching and direct endometrial pressure are probably the most important factors for IUD insertion pain.

Clinical evaluation of drugs used in fertility regulation.

The clinical evaluation of drugs used in fertility regulation is initially assessed in Phase I, II and III trials. The design of each phase and the investigative staff must be adequate. In Phase I, normal, healthy human volunteers meeting specific guidelines are usually studied. Numbers vary between 20 and 80 and the purpose is to determine the acute toxicity of the compound. In Phase II, efficacy and safety are examined in a clinical target population, and emphasis may be placed on pharmacological and mechanistic studies. Usually between 50 and 200 patients are involved. In Phase III, large-scale clinical studies for local registration and the introduction of drugs to various countries are included. This paper describes the evaluation of various drugs used in contraception, including NORPLANT implants, and considers the efficiency, safety and acceptability of such drugs. Phase IV studies are usually needed to reveal chronic toxicities or rare events.

PIP: The nature of clinical studies in Phases I to III of various drugs used in contraception, including Norplant implants, are described. International ethical standards generally agree that subjects should give informed consent before entering a study. Study subjects in Phase I of clinical evaluation are generally normal human volunteers who meet very specific selection guidelines. In special cases a target population of patients might be studied. Typically, the number of subjects studied in this phase ranges from 20-80 depending upon the specific product and the specific study objectives. The primary purpose of Phase I studies is to determine the acute toxicity potential of the product. In addition, one may want to determine the pharmacological or metabolic effects of the product. Family Health International (FHI) currently is planning the development of a new vaginal contraceptive product (FD 100). Initial studies will focus on safety parameters associated with the vaginal route. A subsequent Phase I study of FD 100 will provide an initial assessment of efficacy as well as safety. Phase II studies typically provide an opportunity to examine issues of efficacy and safety in a clinical target population and often permit a determination of the dose and dose intervals which will be most appropriate for that particular population and allow for a more definitive evaluation of the pharmacokinetics and, perhaps, bioavailability of a particular formulation. Typically, between 50-200 subjects are enrolled in a series of Phase II studies. The Program for Applied Research on Fertility Regulation and FHI recently have conducted a Phase II evaluation of a norethindrone (NET) pellet implant system. The most important side effect associated with this implant system consisted of changes in menstrual patterns. The Norplant subdermal implant system is in advanced stages of Phase III evaluation in the US and in selected other countries. In all study countries, the principal investigators are specialists in obstetrics and gynecology and the implants are offered to 400-600 healthy, nonlactating women who want to limit their family size. Beyond a typical study of product safety and efficacy, the novel nature of this implant technology has required the incorporation of special approaches into the multinational Phase III evaluation of the Norplant system. The Today-TM contraceptive sponge was approved for marketing by the Food and Drug Administration in 1983 based largely upon a multicenter study conducted by FHI in the US.

IUD insertion at cesarean section--the Chinese experience.

This review reports the experience of nine studies in Chinese maternity hospitals with insertions of an intrauterine device (IUD) at the time of cesarean section. In contrast to the usually high expulsion rates associated with immediate postpartum vaginal insertions, all nine studies reported low expulsion rates, thus resulting in high continuation rates with this procedure, comparable to those with interval insertions. This immediate post-cesarean section insertion procedure was also found to be safe. These findings are of programmatic importance for postpartum family planning delivery services and may eventually lead to an understanding of the expulsion mechanism in postpartum IUD contraception. Results of these reports have been synthesized in this review. Seven of these nine reports were originally in Chinese and were translated into English for the benefit of a broad international audience. Future research directions on this insertion procedure are also discussed.

[Contraceptive development--the view from the U.S.A. in the mid 80s]. / Developpement de produits contraceptifs: la situation aux U.S.A. au milieu des annees 1980.

PIP: Contraceptive research and development in the US has been slowed by declining investment at a time of rising costs and increasingly complex US Food and Drug Administration (FDA) regulation. Public and private investment in contraceptive research reached its maximum in the early 1970s. Since then, investment has stagnated while research and development costs have continued to rise. Development of a new product costs between 50-60 million dollars and corresponds to over 2/3 of its legal life of 17 years. In addition, the majority of pharmaceutical liability cases in the past few years have involved contraceptives. Although recent epidemiological studies have demonstrated that oral contraceptives (OCs) have some significant benefits, such as prevention of at least 2 types of cancer, OCs continue to be held responsible for secondary cardiovascular effects as well as for some effects whose true etiology has not been demonstrated. The growing use of contraceptive sterilization at the expense of most other methods and the opposition to making contraceptives easily available among those who believe that contraception encourages premarital sexual activity are other factors which have resulted in the near abandonment of contraceptive research and development by American pharmaceutical companies, who no longer consider family planning a viable market. In the US, most research and innovation in the field of contraception now comes from not-for-profit institutions such as Family Health International (FHI) the Population Council, and to a lesser extent the Program of Applied Research for Fertility Regulation and some universities. Such organizations receive some research funds from the Agency for International Development and the National Institutes of Health. The role of FHI in the development of the contraceptive sponge and of the Population Council in developemnt of the Copper T 380A IUD demonstrate the transfer of supremacy in contraceptive development from the pharmaceutical industry to social organizations. 2 or 3 sustained release steroid systems, including the Norplant subcutaneous implant system which releases levonorgestrel, the simpler Norplan II system, biodegradable injectable microcapsules containing norethindrone, or subcutaneous steriod pellets, are likely to acheive FDA approval by the early 1990s. Other efforts are underway to develop contraceptive substances using drugs already authorized by the FDA for other indications. Examples of this approach are the use of propranolol and chlorhexidine as vaginal spermicides. A small number of studies are continuing on simplified methods of sterilization appropriate for Third World Countries. An anti-zone pellucida or anti-sperm pregnancy vaccine may be at the stage of clinical testing by 1990, but doubts about product liability may slow prevent clinical utilization in the US. FDA regulations specify the characteristics of required studies but not their location. Because funds are limited but the need for contraception is universal, it is probable that international cooperation in contraceptive development will assume increasing importance.^ieng

Syncope and other vasovagal reactions at interval insertion of Lippes Loop D--who is most vulnerable?

Syncope and other vasovagal reactions occasionally occur at or immediately after IUD insertion. This analysis, using an international data set comprised of interval insertions of Lippes Loop D, found that women who are primiparous (as compared to those who are multiparous), and/or those who want more children are at higher risk for vasovagal reactions and deserve more careful counseling and gentler cervical manipulation. Moderate to severe pelvic pain at insertion is closely associated with the development of vasovagal reaction. Measures to alleviate or prevent pain at insertion could reduce the incidence of vasovagal reactions.

Mitochondrial fluorescence patterns in rhodamine 6G-stained myocardial cells in vitro. Analysis by real-time computer video microscopy and laser microspot excitation.

Cellular fluorescence in vitro has been studied employing a low light-level video system interfaced with a real-time image array-processing computer system. Changes in cytoplasmic (mitochondrial) fluorescence in myocytes employing the probe rhodamine 6G have been studied over real time with the aid of several computer-based programs. An oscillating pattern of fluorescence is observed that appears to reflect localized variations in mitochondrial activity. The low light level video computer system used in this study compares favorably with laser-stimulated microspot fluorescence photon-counting techniques for the detection of subcellular fluorescence.