Virial expansion coefficients in the harmonic approximation.

The virial expansion method is applied within a harmonic approximation to an interacting N-body system of identical fermions. We compute the canonical partition functions for two and three particles to get the two lowest orders in the expansion. The energy spectrum is carefully interpolated to reproduce ground-state properties at low temperature and the noninteracting high-temperature limit of constant virial coefficients. This resembles the smearing of shell effects in finite systems with increasing temperature. Numerical results are discussed for the second and third virial coefficients as functions of dimension, temperature, interaction, and transition temperature between low- and high-energy limits.

Quantum statistics and thermodynamics in the harmonic approximation.

We describe a method to compute thermodynamic quantities in the harmonic approximation for identical bosons and fermions in an external confining field. We use the canonical partition function where only energies and their degeneracies enter. The number of states of given energy and symmetry is found by separating the center-of-mass motion, and by counting the remaining states of given symmetry and excitation energy of the relative motion. The oscillator frequencies that enter the harmonic Hamiltonian can be derived from realistic model parameters, and the method corresponds to an effective interaction approach based on harmonic interactions. To demonstrate the method, we apply it to systems in two dimensions. Numerical calculations are compared to a brute force method, which is considerably more computationally intensive.

Complexity of quantum states in the two-dimensional pairing model.

It is known that many-fermion systems, such as complex atoms and nuclei, reveal (at some level of excitation energy) local signatures of quantum chaos similar to the predictions of random matrix theory. Here, we study the gradual development of such signatures in a model system of up to 16 fermions interacting through short-range pairing-type forces in a two-dimensional harmonic trap. We proceed from the simplest characteristics of the level spacing distribution to the complexity of eigenstates, strength, and correlation functions. For increasing pairing strength, at first, chaotic signatures gradually appear. However, when the pairing force dominates the Hamiltonian, we see a regression towards regularity. We introduce a "phase correlator" that allows us to distinguish the complexity of a quantum state that originates from its collective nature, from the complexity originating from quantum chaos.

Cold fermionic atoms in two-dimensional traps: pairing versus Hund's rule.

The microscopic properties of few interacting cold fermionic atoms confined in a two-dimensional (2D) harmonic trap are studied by numerical diagonalization. For repulsive interactions, a strong shell structure dominates, with Hund's rule acting at its extreme for the midshell configurations. In the attractive case, odd-even oscillations due to pairing occur simultaneously with deformations in the internal structure of the ground states, as seen from pair correlation functions.

Burns from illegal drug manufacture: case series and management.

This case series presents our experience with burns sustained while manufacturing illegal drugs. All adult burn admissions in an 18-month period were retrospectively reviewed. All patients suspected of sustaining burns from illegal drug manufacture were contacted. Information regarding the burn mechanism was sought. Nine of the 64 adult burn admissions were caused by explosions during the manufacture of cannabis oil. Young males with hand and face burns were heavily represented. First-aid treatment was often ignored in favor of hiding incriminating evidence. Only two patients gave honest admission histories. Illegal drug manufacture is becoming more common as synthetic drugs become more consumer desirable. Burns sustained may be thermal and/or chemical. Dishonest patient histories negatively influence burn management. A high level of suspicion is required for diagnosing and treating burns from illegal drug manufacture. Public education is unlikely to be effective as the financial rewards outweigh the perceived risks.

Pulsed dye laser therapy for rosacea.

Rosacea is a chronic and progressive inflammatory skin disorder affecting the facial convexities for which no curative measure is currently available. Forty consecutive patients with rosacea were treated with the Cynosure PhotoGenica V pulsed dye laser. The improvement following laser therapy was assessed according to a sliding scale: 1 (worse after treatment), 2 (no improvement), 3 (slight improvement), 4 (moderate improvement), 5 (marked improvement). Following an average of 2.4 (range 1-10) laser treatments, a mean score of 4.4 and 4.3 for overall improvement was achieved as judged by the patients and independently assessed by a family member or a close friend of the patients, respectively. The response of erythema and telangiectasia to laser therapy, evaluated by an independent panel of 10 members, showed a mean score of 3.7. Three patients experienced an exacerbation of rosacea during the treatment period requiring antibiotic therapy. During the follow-up period of 6.0-55.5 (mean, 23.3) months after completion of laser therapy, no patient (including 13 patients in whom papulation and pustulation which were amongst the presenting symptoms) required medical treatment. Six patients developed post-inflammatory hyper-pigmentation necessitating skin bleach but no other complication such as scarring was observed. Three patients reported that the residual erythema had progressed after an initial improvement during follow-up periods of 52.4, 15.8 and 6.0 months. All patients felt that laser therapy was worthwhile. We conclude that pulsed dye laser therapy is a useful treatment for rosacea.

Barriers to podiatric care among diabetic patients in the San Francisco Bay area.

This study investigates the provision of general medical and foot care, the barriers to access for foot care, and the awareness of foot risks in an urban diabetic population. A survey composed of 26 questions was mailed to 2375 diabetic patients in the San Francisco Bay area who are members of the American Diabetes Association (ADA). Three hundred ninety-two surveys were returned for a response rate of 16%. Of the 392 respondents, 7 (1.8%) indicated that they were not receiving any medial care for their diabetes, with another 15 (3.8%) receiving general medical care from an alternative health care provider. Among the respondents, 87 (22%) did not have their feet examined by any health care provider. The remainder of the patients were receiving foot care from a health care provider with 191 (48.7%) under the care of a provider other than a podiatrist. Of those not receiving any foot care, 53 (61%) reported that they did not seek any pedal care because they do not have any apparent foot or leg problems. Another 12 (13.8%) indicated that they did not know whom to see for their lower extremity problems. Lack of insurance or inability to afford medical care was the main reason that prevented 7 (8%) of the patients from receiving routine foot care. With respect to the patient's knowledge of diabetes-associated foot disorders, the majority (72%-79%) knew that poor circulation, neuropathy, ulcers, painful leg and foot conditions, infection, and amputation were associated with diabetes. From all the surveyors, 106 (27%) reported that they were not advised or educated on the potential lower extremity complications of diabetes by their health care provider. The results of this study indicate that in an urban population of diabetic patients, all of whom were members of ADA, a significant number are not adequately educated on the importance of routine foot care.

Dermofasciectomy in the management of Dupuytren's disease.

Dupuytren's disease may present with well-defined subcutaneous cords or as more diffuse disease with involvement of the skin. Fasciectomy is the procedure commonly carried out for the full range of disease, but is associated with rates of recurrence of up to 66%. We reviewed 143 rays in 103 patients undergoing dermofasciectomy for diffuse disease with involvement of the skin. We found recurrence in 12 rays (8.4% of rays; 11.6% of patients) during a mean follow-up of 5.8 years, eight as cords and four as nodules. We suggest that dermofasciectomy is a better method of disease control than fasciectomy for the more diffuse type of disease with involvement of the skin.

Quantitative analysis of wound healing.

In this article, we initially review several problems associated with the design and interpretation of certain types of experiments currently used to study wound healing, drawing attention to the fact that applications for standard statistical techniques in the analysis of the experimental results are often of limited value. We then argue that, because of the special nature of wound healing data, curve fitting of empirical model equations can often provide a convenient way to summarize treatment effects with large data sets. The various ways in which this technique could be used to facilitate the interpretation of experimental wound healing results are then explored. To illustrate this approach, we then took several wound healing experiments and introduced possible models that could be used, paying particular attention to simple equations with the smallest possible number of parameters. For each equation, the way that the parameters of the model could be interpreted with regard to the biologic effects represented is given. Examples are given to show the application of each model discussed theoretically in the interpretation of some typical experimental data sets.

Ontogeny of the skin and the transition from scar-free to scarring phenotype during wound healing in the pouch young of a marsupial, Monodelphis domestica.

The marsupial Monodelphis domestica provides a versatile model for the study of "fetal" wound healing. The pouch young of this species have been used to perform a systematic histological study of wound healing and skin development throughout pouch life; from Pouch Day 0 to Pouch Day 30 with comparisons drawn against adults. We have demonstrated that pouch young heal without macroscopic scars if wounded before Pouch Day 9 and that a transition into a scarring healing phenotype occurs around the ninth pouch day. The inflammatory reaction of wounds and aspects of skin differentiation such as dermal collagen organisation, adipose layer development, hair follicle growth, and epithelial maturation have been documented using simple ranking scales to highlight trends through pouch life. Inflammation was noted to become prominent after Pouch Day 9. There was also a general temporal correlation between the other aspects of differentiation and the transition into a scarring phenotype. It is concluded that although fetal wounds may have different cytokine profiles due to the differences of inflammatory reaction compared to adults, other aspects of skin development play a role in determining the healing phenotype.

A homodigital reverse pedicle island flap in soft tissue reconstruction of the finger and the thumb.

A single stage homodigital reverse pedicle island flap is described for the repair of volar or dorsal tissue loss on the finger or thumb. Donor site morbidity is minimal, and the length of the digit is preserved. Satisfactory function results in 25 patients are presented.

Variation in attractiveness of human subjects to malaria mosquitoes (Diptera: Culicidae) in The Gambia.

During experimental hut trials to assess the efficacy of insecticide-treated bednets against malaria mosquitoes, we observed that human subjects varied consistently in their attractiveness to mosquitoes. Attractiveness was assessed by estimating the numbers of wild Anopheles gambiae Giles mosquitoes entering a hut in which a man was sleeping, and the numbers of human-bloodfed An. gambiae sensu lato collected from each hut each morning. Five trials were carried out at Wali Kunda in rural Gambia during 2.5 yr. During each 6-wk trial a man slept under a bednet in each of the six huts. Morning collections of mosquitoes from the room, enclosed verandas, and window traps of each hut provided estimates of the number of mosquitoes that had entered during the night. Blood meals were analyzed using an ELISA technique to identify those mosquitoes feeding on humans. Specimens were collected by field workers, not the subjects; therefore, sampling was independent of the subjects' ability to catch mosquitoes. Moreover, the trials were designed to measure the relative attractiveness of individual sleepers to mosquitoes, allowing for other sources of variation (i.e., among huts, bednets, nights, and day of the week). Attractiveness of men to mosquitoes differed significantly among individuals as indicated by the consistent differences between the numbers of mosquitoes entering each man's hut and the numbers feeding on each man. However, the two measures of attractiveness were apparently independent of each other: subjects who attracted consistently high numbers of vectors into their hut did not necessarily have high numbers of mosquitoes feeding on them. These findings support the view that some individuals within a community are at greater risk from mosquito-borne pathogens than others.

For a few parasites more: Inoculum size, vector control and strain-specific immunity to malaria.

What precipitates malaria illness in an area of intense transmission? Greenwood, Marsh and Snow(1) and Marsh(2) have discussed the hypothesis that the severity of malaria depends on the size of the inoculum, that is, on the number of sporozoites inoculated at one time(3). According to these authors, this is suggested by the results of vector control trials in which parasite prevalence remained the same but episodes of disease were reduced. This is clearly an important observation, but Jo Lines and Jo Armstrong interpret it differently. They see the primary implication of these results as being that natural immunity to malaria must be largely strain specific, and only if there is strain specificity can inoculum size be important. Here they present arguments to support this view,and point out that, if there is strain specific immunity, then short-term evaluation o f vector control is likely to overestimate its long-term benefit.

Malaria chemoprophylaxis, birth weight and child survival.

Study of the effects of malaria chemoprophylaxis given during pregnancy on birthweight and investigation of the influence of birthweight on child survival suggest that, in a rural area of The Gambia, chemoprophylaxis given during pregnancy might reduce infant mortality by about one-fifth in the children of primigravidae but by less than 5% in the children of multigravidae. In malaria endemic areas, primigravidae should be protected against malaria not only for their own sake but also for that of their infants.

PIP: Over 3 years, researchers randomly assigned more than 1775 pregnant women (many in their 3rd trimester of pregnancy) from 41 villages near Farafenni, The Gambia, to receive either Maloprim (malaria chemoprophylaxis of pyrimethamine and dapsone) or a placebo to determine Maloprim's effects on birth weight and child survival. All births occurred at home. Field workers went to each home as soon as possible after delivery to weigh the newborns. The relative risks for neonatal and infant mortality were 23 for infants weighing less than 2000 gms and 12 for those who weighed at least 2500 gms. While they were 2.1 and 0.8, respectively, for infants weighing between 2000 and 2500 gms. 33.3% of low birth weight infants of primigravidae died compared with 19% of those of multigravidae. Taking Maloprim during pregnancy reduced infant mortality by 18% for infants of primigravidae and only 4% for infants of multigravidae. It reduced neonatal deaths by 42% for infants of primigravidae and by just 6% for infants of multigravidae. These results suggested that health workers should distribute antimalarial medicine to all primigravidae. Chemoprophylaxis along with other malaria control efforts, such as insecticide impregnated bed nets or a malaria vaccine, would protect mothers and their infants.

Childhood deaths in Africa: uses and limitations of verbal autopsies.

The verbal autopsy (VA) is an epidemiological tool that is widely used to ascribe causes of death by interviewing bereaved relatives of children who were not under medical supervision at the time of death. This technique was assessed by comparison with a prospective survey of 303 childhood deaths at a district hospital in Kenya where medically confirmed diagnoses were available. Common causes of death were detected by VA with specificities greater than 80%. Sensitivity of the VA technique was greater than 75% for measles, neonatal tetanus, malnutrition, and trauma-related deaths; however, malaria, anaemia, acute respiratory-tract infection, gastroenteritis, and meningitis were detected with sensitivities of less than 50%. There may have been unwarranted optimism in the ability of VAs to detect some of the major causes of death, such as malaria, in African children. VA used in malaria-specific intervention trials should be interpreted with caution and only in the light of known sensitivities and specificities.

Pyrethroid-treated bednet effects on mosquitoes of the Anopheles gambiae complex in The Gambia.

The response of Anopheles gambiae complex mosquitoes to men sleeping under insecticide-impregnated or untreated bednets in six verandah trap huts was studied during the dry season in The Gambia. With this type of hut it was possible to collect live and dead indoor-resting mosquitoes and estimate the number of wild mosquitoes which entered, bloodfed on man, and exited each night. Bednets were treated with emulsions targetted to leave deposits of 25 mg/m2 lambda-cyhalothrin, or 5, 50 or 500 mg/m2 permethrin, diluted from emulsifiable concentrates (EC), or a blank formulation similar to the EC except that the permethrin was omitted; the sixth net was left untreated. Nets and sleepers were rotated between huts on different nights, the design being based on a series of Latin squares and conducted double-blind. Permethrin-impregnated bednets deterred mosquitoes from entering the huts. The degree of deterrency was proportional to the dosage of permethrin. This effect was also caused by the blank formulation and therefore attributed to other components of the formulation, rather than to the permethrin itself. The net impregnated with 500 mg permethrin per square metre gave the best individual protection, reducing mosquito bloodfeeding by 91% compared with untreated nets. However, lambda-cyhalothrin was proportionately more insecticidal than permethrin at doses of equivalent deterrency. At this stage of research, it remains conjectural whether chemical deterrency or killing of malaria vectors is better for community protection.

Experimental hut trials of bednets impregnated with synthetic pyrethroid or organophosphate insecticide for mosquito control in The Gambia.

1. Nylon bednets impregnated with different insecticides were evaluated in 1988 against wild adult mosquito populations, mostly Mansonia africana (Theobald) and Anopheles gambiae Giles sensu lato, entering experimental verandah-trap huts in The Gambia. Each bednet had six 10 x 10 cm holes made in the walls to simulate torn conditions and permit female mosquitoes to enter and feed on sleepers. 2. Individual net treatments, determined by gas chromatography of net samples from before and after 12 weeks use of the bednets, were: permethrin 670 +/- 159 and 405 +/- 190 mg/m2 (40% loss), cypermethrin 37 +/- 8 and 16 +/- 9 mg/m2 (57% loss), deltamethrin 10 +/- 7 and 10 +/- 8 mg/m2 (no loss), lambda-cyhalothrin 2.6 +/- 0.9 and 1.6 +/- 0.5 mg/m2 (38% loss), pirimiphos-methyl 4017 +/- 117 and 1160 +/- 319 mg/m2 (71% loss). 3. Washing three times in the traditional manner with local cow-fat soap reduced the initial dosages by about 85% of cypermethrin and lambda-cyhalothrin, 99.8% of pirimiphos-methyl and left no detectable residues of deltamethrin or permethrin. 4. The unwashed permethrin-treated bednet reduced the number of mosquitoes entering a hut by 60% of An.gambiae s.l. and 68% of Mansonia spp. This deterrency was less pronounced with the other insecticides and was lost by washing the bednets. 5. Each insecticide, especially lambda-cyhalothrin and pirimiphosmethyl, caused significant mortality rates of mosquitoes that entered huts with impregnated bednets, and prevented the majority of An. gambiae s.l. and Mansonia females from bloodfeeding. Washing completely removed the efficacy of deltamethrin and permethrin treated bednets, whereas nets treated with cypermethrin, lambda-cyhalothrin or pirimiphos-methyl remained significantly insecticidal after washing. 6. Aerial toxicity from the pirimiphos-methyl treated bednet killed 80% of An.gambiae s.l. confined overnight in the hut at the end of the trial, whereas the pyrethroid-treated bednets gave negligible mortality rates of mosquitoes. 7. Sleepers using the bednets had no medical symptoms significantly associated with any of the treatments. On the contrary, from 216 interviews, 4/10 complaints were associated with the use of untreated nets (P approximately 0.05), perhaps because sleepers were kept awake by mosquitoes and became more aware of any ailments. 8. It is concluded that permethrin tends mainly to deter mosquitoes from house-entry, enhancing personal protection, whereas the other insecticides kill higher proportions of the endophilic mosquitoes, which would give better community protection against malaria transmission.