Intermediate Incidence Research Articles

Double ionization of a negative hydrogen ion by positron and electron impact athigh and intermediate energies

Double ionization (DI) of a negative hydrogen ion (H−)has been studied in a comparative manner by e and e+ impactsat high and intermediate incident energies using the framework of the Coulomb–Bornapproximation. Unlike other existing theories for the DI process of H−, thepresent model is the first one to take account of the residual Coulomb potential betweenthe projectile and the ionic target and as such distinguishes between the e and e+results (fully differential cross sections), thereby allowing for the study of thecharge asymmetry in such DI processes. Furthermore, due to the neglect of thelong-range Coulomb interaction between the incident e/e+ and the targetH−ion in both the channels in the previous models, the perturbing potential does notvanish asymptotically with these approaches and the wavefunctions do not satisfy theproper asymptotic boundary conditions for the particular ionization process. Thepresent model is free from this defect. The expected symmetry about the ±q (momentumtransfer) direction in the first-order theories is broken in the present model, indicatingthe presence of non-first-order effects. Deviations from the dipolar limit (q → 0) for optical transitions(γ, 2e)are also discussed. This behaviour corroborates with the experimental findings forinert gas targets, there being no experiments for the (e, 3e) of H− asyet. Results are presented for some selected kinematics (both symmetrical andasymmetrical) chosen in accordance with the experiments on the (e, 3e) process ofinert gas targets.

Reação de híbridos de milho à podridão branca da espiga

Neste trabalho, avaliou-se a reação de seis híbridos de milho (Zea mays)(AG 9012, C 808, P 3041, C 901, XL 212 e X 9403) de germoplasmas diferentes, a Diplodia maydis inoculados artificalmente nas espigas e à infecção natural de D. maydis e de D. macrospora. O híbrido X 9403 apresentou a menor incidência de grãos infetados e o rendimento de grãos superior dos demais híbridos; o híbrido XL 212 apresentou incidência e rendimento de grãos intermediários. Esses dois híbridos possuem textura de grãos dentados. Os híbridos P 3041, AG 9012 e C 808, com textura de grãos duro, apresentaram rendimentos inferiores e reações variáveis a D. maydis e a D. macrospora. Esses resultados mostraram que existe variabilidade entre híbridos quanto à reação à podridão da espiga causada por D. maydis e a D. macrospora. Na identificação de materiais resistentes, se sugere utilizar métodos artificiais de inoculação, visando aumentar a pressão de seleção e confiabilidade nos resultados.

A stochastic, multiscale model of microwave backscatter from the ocean

The conventional view of microwave backscatter from the ocean is based on composite surface and quasi‐specular theories. In this view, backscatter at intermediate incidence angles is due to Bragg scattering from freely propagating short surface waves that are advected and modulated by longer waves. At small incidence angles the scattering process becomes quasi‐specular, coming from small facets aligned normal to the incident waves. The transition between these two processes is said to occur at incidence angles of about 10° to 20°. In this paper we demonstrate that advances in scattering theory and in computing speed make it possible to improve this view. We show that recent scattering theories agree on the form of the backscatter for incidence angles below that where multiple scattering must be considered, i.e., below about 80°. This form involves the Kirchhoff integral multiplied by a coefficient dependent on dielectric constant and incidence angle. We avoid the higher‐order calculations necessary in these theories to include the variable local incidence angle caused by surface wave slopes by applying them over restricted regions of the surface. We successively break the surface into regions from which the scatter comes from small‐, intermediate‐, and large‐scale waves. We show that in this picture, scattering from small‐scale waves is classic Bragg scattering and is very common while from large‐scale waves it is classic quasi‐specular scattering and is rarely important. For intermediate‐scale waves we evaluate the Kirchhoff integral numerically; this type of scattering becomes increasingly important with increasing wind speed. For all scales but the large one we correct the incidence angle for the slopes of all longer waves as required by composite surface theory. On this picture the transition from Bragg scattering to Kirchhoff scattering occurs gradually in a manner that is dependent on incidence angle, azimuth angle, wind speed, and the surface wave spectrum. The model indicates that Bragg scattering is often viable to surprisingly low incidence angles at low wind speeds. The model is sensitive to the wave height variance spectrum over a wide range of wave numbers. We use two recently published forms of this spectrum to compare the predictions of the model to various data that have been collected over the incidence angles range from 0° to 50°. At 0° this model produces a better fit to Ku band data from the TOPEX altimeter than does quasi‐specular theory and does so with no artificial “effective reflection coefficient.” As the incidence angle increases, the model continues to show good agreement with data without an artificial division into “quasi‐specular” and “Bragg” scattering. The advantage of this formulation over a quasi‐specular one is demonstrated by comparing the two models with data on received power taken at 36 GHz for incidence angles between nadir and 30°.

Measurement of Neutron-Production Double-Differential Cross Sections for Intermediate Energy Pion Incident Reaction

Neutron-production double-differential cross sections for 870-MeV π+ and π− and 2.1-GeV π+ mesons incident on iron and lead targets were measured with NE213 liquid scintillators by time-of-flight technique. NE213 liquid scintillators 12.7 cm in diameter and 12.7 cm thick were placed in directions of 15, 30, 60, 90, 120 and 150°. The typical flight path length was 1.5 m. Neutron detection efficiencies were derived from the calculation results of SCINFUL and CECIL codes. The experimental results were compared with the JAM code. The double differential cross sections calculated by the JAM code disagree with experimental data at neutron energies below about 30 MeV. JAM overestimates π+-incident neutron-production cross sections in forward angles at neutron energies of 100 to 500 MeV.

Accuracy of the initial endoscopic diagnosis in the discrimination of gastric ulcers: is endoscopic follow-up study always needed?

Endoscopic follow-up study of gastric ulcers has been recommended routinely because of the possibility that a gastric neoplasm will be missed in the initial endoscopy. Some authors, most of them reporting data from areas of low gastric carcinoma incidence, have questioned this policy because of the low numbers of curable cancers detected and the high cost of such a program. To assess the accuracy of endoscopy diagnosis of gastric ulcers, and to evaluate the efficacy and cost of a gastric ulcer follow-up endoscopic program in an area with an intermediate incidence rate of gastric cancer. A retrospective study was used to identify all the gastroscopies in which a gastric ulcer had been diagnosed during a 6-year period. The endoscopic impression was compared with the histologic diagnosis, sensitivity, specificity, positive and negative predictive values, and the likelihood ratio. Patients who completed a follow-up program also were reviewed. For each neoplasm discovered, the number of endoscopies and global cost were calculated. In the 741 gastroscopies performed, 547 gastric ulcers were diagnosed in 529 patients. Biopsies were taken in 330 patients, in whom 341 gastric ulcers were found. At the index endoscopy, 41 gastric neoplasms (12.4%) were diagnosed. The accuracy of endoscopic malignancy diagnosis was as follows: positive predictive value of 0.68, negative predictive value of 0.98, sensitivity of 0.82, and specificity of 0.95. The likelihood ratio was 16. A total of 117 patients completed the follow-up program. Three new cases of gastric cancer (2.6%) were identified. In these three cases, the initial opinion of the endoscopist was uncertain. In the authors' experience, the cost of each gastric cancer diagnosed has been $4.653 (U.S. dollars). The endoscopic impression correlates with the histologic diagnosis even in a area of intermediate gastric cancer incidence. Endoscopic follow-up study may be restricted to cases of uncertain or malignant endoscopic impression.

Epidemiology of hepatocellular carcinoma

Because of its high incidence in many of the most populous countries in the world, its often fulminant course, poor response to conservative treatment, low resectabilty rate when symptomatic, high recurrence rate after resection and liver transplantation, and grave prognosis, hepatocellular carcinoma is now regarded as one of the major malignant diseases. Hepatocellular carcinoma is the most common primary malignant tumour of the liver. Relative to other tumours, it ranks fifth in overall frequency (fifth in men and eighth in women) and fourth in annual mortality rate. An estimated 372 000 new cases of hepatocellular carcinoma are diagnosed each year, constituting 4.6% of all new human cancers (6.3% in men; 2.7% in women). The annual mortality rate from the tumour is virtually the same as its annual incidence. The highest incidences occur in eastern and southeastern Asia, some of the Western Pacific islands, and sub-Saharan Africa. Intermediate incidences are found in eastern and southern Europe, the Caribbean, Central America, and Western Asia. Hepatocellular carcinoma is uncommon in the remaining countries. Men are affected more often than are women. The incidence generally increases with increasing age, although there is a definite shift towards a younger age distribution in black African and ethnic Chinese populations.

Species Diversity and Abundance of Vascular Epiphytes on Vellozia piresiana in Brazil1

ABSTRACTThe composition, structure, and ecology of epiphyte communities have been intensely studied in tropical rain forests. Studies involving epiphytes, however, are scarce in other vegetational physiognomies. This study examined the composition of an epiphyte community on Vellozia piresiana (Velloziaceae) in a Brazilian rupestrian field, and investigated the factors influencing their abundance and distribution. In July 1998, 98 individuals of V. piresiana were sampled inside three transects in rocky outcrops of Serra do Cipó, Minas Gerais, and their height were measured. All epiphytes growing on these phorophytes were counted and identified. Height and branch diameter at which each epiphyte individual occurred were recorded. Luminosity intensity was measured in the upper canopy, middle canopy, and 10 cm above ground 100 phorophytes in the same population; 712 epiphytes were found growing on V. piresiana belonging to six species: Vrisea oligantha (Bromeliaceae; 344 individuals), Epidendrum saxatile (251), Constancia ci‐poencis (50), Prosthechea vespa (31) Sophronites brevipedunculata (30; all Orchidaceae), and Tillandsia usneoides (1; Bromeliaceae). A higher abundance of epiphytes occurred at intermediate heights on the phorophytes, probably because of an intermediate light incidence at these positions. We found epiphytic species across different distributions, both in terms of height and branch diameter of V, piresiana, which may have reflected distinct degrees of tolerance to drought and excessive luminosity. These results indicated that despite the low richness observed in this study, the epiphyte community on V. piresiana presented ecological features similar to that observed for tropical rain forests (e.g., phorophyte partitioning and differential vertical distribution).RESUMESThe composition, structure, and ecology of epiphyte communities have been intensely studied in tropical rain forests. Studies involving epiphytes, however, are scarce in other vegetational physiognomies. This study examined the composition of an epiphyte community on Vellozia piresiana (Velloziaceae) in a Brazilian rupestrian field, and investigated the factors influencing their abundance and distribution. In July 1998, 98 individuals of V. piresiana were sampled inside three transects in rocky outcrops of Serra do Cipó, Minas Gerais, and their height were measured. All epiphytes growing on these phorophytes were counted and identified. Height and branch diameter at which each epiphyte individual occurred were recorded. Luminosity intensity was measured in the upper canopy, middle canopy, and 10 cm above ground 100 phorophytes in the same population; 712 epiphytes were found growing on V. piresiana, belonging to six species: Vrisea oligantha (Bromeliaceae; 344 individuals), Epidendrum saxatile (251), Constancia ci‐poencis (50), Prosthechea vespa (31) Sophronites brevipedunculata (30; all Orchidaceae), and Tillandsia usneoides (1; Bromeliaceae). A higher abundance of epiphytes occurred at intermediate heights on the phorophytes, probably because of an intermediate light incidence at these positions. We found epiphytic species across different distributions, both in terms of height and branch diameter of V, piresiana, which may have reflected distinct degrees of tolerance to drought and excessive luminosity. These results indicated that despite the low richness observed in this study, the epiphyte community on V. piresiana presented ecological features similar to that observed for tropical rain forests (e.g., phorophyte partitioning and differential vertical distribution).

Species Diversity and Abundance of Vascular Epiphytes on Vellozia piresiana in Brazil1

The composition, structure, and ecology of epiphyte communities have been intensely studied in tropical rain forests. Studies involving epiphytes, however, are scarce in other vegetational physiognomies. This study examined the composition of an epiphyte community on Vellozia piresiana (Velloziaceae) in a Brazilian rupestrian field, and investigated the factors influencing their abundance and distribution. In July 1998, 98 individuals of V. piresiana were sampled inside three transects in rocky outcrops of Serra do Cipo ´, Minas Gerais, and their height were measured. All epiphytes growing on these phorophytes were counted and identified. Height and branch diameter at which each epiphyte individual occurred were recorded. Luminosity intensity was measured in the upper canopy, middle canopy, and 10 cm above ground 100 phorophytes in the same population; 712 epiphytes were found growing on V. piresiana, belonging to six species: Vrisea oligantha (Bromeliaceae; 344 individuals), Epidendrum saxatile (251), Constancia cipoencis (50), Prosthechea vespa (31) Sophronites brevipedunculata (30; all Orchidaceae), and Tillandsia usneoides (1; Bromeliaceae). A higher abundance of epiphytes occurred at intermediate heights on the phorophytes, probably because of an intermediate light incidence at these positions. We found epiphytic species across different distributions, both in terms of height and branch diameter of V. piresiana, which may have reflected distinct degrees of tolerance to drought and excessive luminosity. These results indicated that despite the low richness observed in this study, the epiphyte community on V. piresiana presented ecological features similar to that observed for tropical rain forests (e.g., phorophyte partitioning and differential vertical distribution).

The effects of metallic underlayers on magnetic properties of obliquely sputtered Co thin films

By using oblique sputtering, Co films have been grown on polymer substrate (PET) with and without metallic underlayers such as Cu and Al. The microstructure and magnetic properties have been investigated at large as well as intermediate incident angle of deposition. It was confirmed that the underlayer induces a significant change in microstructure by isolating the nuclei and reducing their sizes. Consequently, the magnetic properties are strongly affected due to the low magnetocrystalline anisotropy (face-centered-cubic Co). Other analyses (Δ M, MFM) support these observations.

Risk factors for cancer of the oral cavity and oro-pharynx in Cuba.

In terms of worldwide levels, Cuba has an intermediate incidence of cancer of the oral cavity and oro-pharynx. We studied 200 cases of cancer of the oral cavity and pharynx, of whom 57 women (median age = 64) and 200 hospital controls, frequency matched with cases by age and sex, in relation to smoking and drinking history, intake of 25 foods or food groups, indicators of oral hygiene and sexual activity, and history of sexually transmitted diseases. Odds ratios (OR) and 95% confidence intervals (CI) were obtained from unconditional multiple logistic regressions and adjusted for age, sex, area of residence, education, and smoking and drinking habits. In the multivariate model, high educational level and white-collar occupation, but not white race, were associated with halving of oral cancer risk. Smoking ≥30 cigarettes per day showed an OR of 20.8 (95% CI: 8.9–48.3), similar to smoking ≥4 cigars daily (OR = 20.5). Drinking ≥ 70 alcoholic drinks per week showed an OR of 5.7 (95% CI: 1.8–18.5). Hard liquors were by far the largest source of alcohol. Increased risk was associated with the highest tertile of intake for maize (OR = 1.9), meat (OR = 2.2) and ham and salami (OR = 2.0), whereas high fruit intake was associated with significantly decreased risk (OR = 0.4). Among indicators of dental care, number of missing teeth and poor general oral condition at oral inspection showed ORs of 2.7 and 2.6, respectively. Number of sexual partners, marriages or contacts with prostitutes, practice of oral sex and history of various sexually transmitted diseases, including genital warts, were not associated with oral cancer risk. 82% of oral cancer cases in Cuba were attributable to tobacco smoking, 19% to smoking cigars or pipe only. The fractions attributable to alcohol drinking (7%) and low fruit intake (11%) were more modest. Thus, decreases in cigarette and cigar smoking are at present the key to oral cancer prevention in Cuba. © 2001 Cancer Research Campaign http://www.bjcancer.com

Measurement of Neutron-Production Double-Differential Cross Sections for Intermediate Energy Pion Incident Reaction

Neutron-production double-differential cross sections for 870-MeV π+ and π - and 2.1-GeV π+ mesons incident on iron and lead targets were measured with NE213 liquid scintillators by time-of-flight technique. NE213 liquid scintillators 12.7cm in diameter and 12.7cm thick were placed in directions of 15°, 30°, 60°, 90°, 120° and 150°. The typical flight path length was 1.5 m. Neutron detection efficiencies were derived from the calculation results of SCINFUL and CECIL codes. The experimental results were compared with the cascade-evaporation calculation code NUCLEUS. The calculation results are higher typically by a factor of two than the experimental data at neutron energies below about 30MeV. NUCLEUS overestimates π+-incident neutron-production cross sections in forward angles at neutron energies of 100 to 500 MeV.

Low energy electron impact on C 76 and C 84: excitation, metastable anion formation, and lifetime

Low energy (0–15 eV) electron impact on gas phase fullerenes C 76 and C 84 has been investigated in an e − beam experiment (electron energy resolution 0.050 eV). Electron energy loss spectroscopy results are presented for C 76 at intermediate and low incident energy and are compared with the UV–visible absorption spectrum. The lowest triplet state 3 B 3 has not been detected; however, two bands at 1.70 and 2.58 eV, clearly of triplet character are observed. The band at 1.70 eV is assigned to 3 B 1 and 3 B 2 states. Ion yields of C 76 − and C 84 − versus e − energy are presented in the range 0–10 eV. The capture threshold is shown to appear at zero energy (within 0.030 eV), indicating the occurrence of an s-wave capture. The nature of other features due to resonances appearing on the spectrum is discussed. Lifetimes τ of C 76 − and C 84 − are observed to be strongly dependent of the electron energy. They are reported in the range 10–15 eV. For the capture of a 14 eV electron we have measured τ(C 76 −) = 100 μs and τ(C 84 −) = 180 μs. Comparison between the lifetimes of C 60 −, C 70 −, C 76 −, and C 84 − shows that τ behaves exponentially with the number of carbon atoms involved in the fullerene anion.

Measurement of Neutron-Production Double-Differential Cross Sections for Intermediate Energy Pion Incident Reaction.

Neutron-production double-differential cross sections for 870-MeV π+ and π - and 2.1-GeV π+ mesons incident on iron and lead targets were measured with NE213 liquid scintillators by time-of-flight technique. NE213 liquid scintillators 12.7cm in diameter and 12.7cm thick were placed in directions of 15°, 30°, 60°, 90°, 120° and 150°. The typical flight path length was 1.5 m. Neutron detection efficiencies were derived from the calculation results of SCINFUL and CECIL codes. The experimental results were compared with the cascade-evaporation calculation code NUCLEUS. The calculation results are higher typically by a factor of two than the experimental data at neutron energies below about 30MeV. NUCLEUS overestimates π+-incident neutron-production cross sections in forward angles at neutron energies of 100 to 500 MeV.

Epidemiology of Musculoskeletal and Soft Tissue Injuries aboard a U.S. Navy Ship

The objective of this study was to characterize injuries occurring to crew members aboard a U.S. Navy ship. A retrospective review of crew member medical records was conducted covering a 90-day period during which the ship was intermittently at sea. Data on new injuries were collected and sorted. Injuries were classified as soft tissue or musculoskeletal, acute or overuse, and occurring with the ship at sea or in port. There was a total incidence of 16.5 injuries per 100 man-months. Acute musculoskeletal injuries contributed 2.6 injuries per 100 man-months and resulted in 79 lost and 192.5 modified work days. Overuse musculoskeletal injuries were responsible for 9.3 injuries per 100 man-months and caused 1 lost and 255.5 modified work days. Soft tissue injuries had an incidence of 4.6 injuries per 100 man-months and resulted in no lost and only 106 modified work days. The relative risk of sustaining a soft tissue injury in port compared with at sea was 1.1, but this was not statistically significant. The relative risk of sustaining an acute musculoskeletal injury in port compared with at sea was 3.5 (p = 0.01). Overuse musculoskeletal injuries occurred with the greatest incidence, but acute musculoskeletal injuries were responsible for the greatest morbidity. Soft tissue injuries occurred with an intermediate incidence but had the lowest overall morbidity. The safest place for crew members assigned to this Navy ship was aboard that ship at sea. Further studies of this nature could help guide medical efforts at injury treatment and prevention for shipboard personnel.

Incidence of childhood type 1 diabetes worldwide. Diabetes Mondiale (DiaMond) Project Group.

To investigate and monitor the patterns in incidence of childhood type 1 diabetes worldwide. The incidence of type 1 diabetes (per 100,000 per year) from 1990 to 1994 was determined in children < or =14 years of age from 100 centers in 50 countries. A total of 19,164 cases were diagnosed in study populations totaling 75.1 million children. The annual incidence rates were calculated per 100,000 population. The overall age-adjusted incidence of type 1 diabetes varied from 0.1/100,000 per year in China and Venezuela to 36.8/100,000 per year in Sardinia and 36.5/100,000 per year in Finland. This represents a >350-fold variation in the incidence among the 100 populations worldwide. The global pattern of variation in incidence was evaluated by arbitrarily grouping the populations with a very low (<1/100,000 per year), a low (1-4.99/100,000 per year), an intermediate (5-9.99/100,000 per year), a high (10-19.99/100,000 per year), and a very high (> or =20/100,000 per year) incidence. Of the European populations, 18 of 39 had an intermediate incidence, and the remainder had a high or very high incidence. A very high incidence (> or =20/ 100,000 per year) was found in Sardinia, Finland, Sweden, Norway Portugal, the U.K., Canada, and New Zealand. The lowest incidence (<1/100,000 per year) was found in the populations from China and South America. In most populations, the incidence increased with age and was the highest among children 10-14 years of age. The range of global variation in the incidence of childhood type 1 diabetes is even larger than previously described. The earlier reported polar-equatorial gradient in the incidence does not seem to be as strong as previously assumed, but the variation seems to follow ethnic and racial distribution in the world population.

Positron impact ionisation of He ion

Triple differential cross-sections (TDCS) of a hydrogenic (He+) ion has been studied by positron impact using coplaner geometry for both symmetric and asymmetric kinematics in the intermediate and medium high incident energy region. TDCS has also been studied of He+ ion by electron impact for symmetric kinematics taking account of the electron exchange effect. The final state wavefunction is chosen as the correlated 3-body Coulomb wavefunction satisfying the exact asymptotic boundary condition. The long range Coulomb interaction in the initial channel between the ionic target and the projectile has also been taken into account properly. For positron impact, the collision is found to be almost recoilless at lower incident energies, in contrast to the strong recoil peak noted in the case of electron impact ionisation. For electron impact, the exchange effect is found to be significantly high for equal energy sharing in the final channel.

A theory on the distribution function of backscatter radar cross section from ocean waves of individual wavelength

A new and simple method of interpreting the of the backscatter radar cross section (RCS) from ocean waves of individual wavelength is presented. Using the Kirchhoff scattering (Physical Optics) theory, the RCS from the ambient waveheight spectrum is first computed as a function of the wavenumber. Differentiating this cumulative RCS yields the distribution function of the RCS from ocean waves of different wavenumbers. The present study shows, as a general feature, that the maximum RCS contribution tends to come from the ocean waves of wavenumbers closer to the Bragg wavenumber as the radar incidence angle increases. Under low wind speeds (/spl sim/2 m/s) and at incidence angles between 200 and 45/spl deg/, the dominant RCS contribution at both C-band and L-band comes from ocean waves of wavenumbers close to the Bragg wavenumber. Under intermediate to high wind speeds (/spl sim/10-15 m/s) and at the small incidence angle of 200, the radar backscatter is dominated by long ocean waves with little contribution from the Bragg waves at both bands. At the intermediate incidence angles (/spl sim/35/spl deg/ to 45/spl deg/), the RCS distribution is centered at wavenumbers near the Bragg wavenumber at all wind speeds from 2 m/s to 15 m/s. These features are more pronounced at C-band than at L-band. The present theory is based on the Kirchhoff scattering model, and as such, its validity may also be limited to a range of small to intermediate incidence angles where the polarization effect is not very significant. The RCS distribution is evaluated for the ambient sea surface and the surface perturbed by varying currents induced by the interaction between the current and bottom topography.

Outcome of Tuberculosis Treatment: A Comparison between Alberta and Nicaragua

To measure the outcome of tuberculosis treatment in a low incidence, high income region, Alberta, and compare with an intermediate incidence, low income country with a model national tuberculosis program, Nicaragua. All 1992 sputum smear-positive pulmonary cases from both regions were included. Treatment outcome was assigned retrospectively to Alberta cases according to the International Union Against Tuberculosis and Lung Diseases' (IUATLD) criteria of cure, failure, transfer, absconder and death. Alberta laboratories are required to report all Mycobacterium tuberculosis cultures to Alberta provincial tuberculosis services. Nicaragua cases are reported centrally to the Programa de control de tuberculosis in Managua using the IUATLD criteria. In Alberta, 222 tuberculosis cases were identified, of which 61 were smear positive. Nicaragua had 1552 smear positive cases of 2885 tuberculosis cases. Alberta's outcomes were 82% cured, no failed treatment, 5% absconded, 2% transferred and 11% died; Nicaragua's outcomes were 77% cured, 2% failed, 13% absconded, 5% transferred and 4% died. There was no significant difference in cure rates between Alberta and Nicaragua, P=0.33. Treatment outcomes can be measured effectively and reported in high income, low incidence settings. Alberta is achieving comparable cure rates with the Nicaraguan national tuberculosis program.

Evaluation of a selective screening for colorectal carcinoma

Although the efficacy of mass screening for colorectal carcinoma (CRC) with a fecal occult blood test has been demonstrated in several randomized trials, a mass screening approach used in countries with intermediate or low incidence of CRC might be costly. Screening high risk people may be an alternative approach, to aid in the prevention of death from CRC. However, the efficacy of CRC screening for high risk people in such countries is uncertain. For this study, a multicenter design was devised to identify high risk groups without clinical symptoms related to CRC; these subjects were identified through the study of index cases of CRC in Taiwan. Colonoscopy, in combination with a fecal occult blood test or double-contrast barium enema, was used to screen high risk groups. A total of 8909 subjects were invited to attend screening. Of 8909, 81 with asymptomatic CRC were detected in one-shot screening. Markov models, in conjunction with a simulated approach, were proposed to estimate relevant parameters in relation to disease progression and to assess the effect of the interval between screenings on the efficacy of CRC screening for these high risk groups. The estimated preclinical incidence rate was 0. 00396 (95% confidence interval [CI], 0.002944-0.004985), which was 21 times that reported from a cancer registry in 1994. The simultaneous estimations of mean sojourn time (the average duration between the preclinical screen-detectable phase and the clinical phase) and sensitivity were 2.8 years (95% CI, 2.15-4.30) and 95.0% (95% CI, 24.4-99.9%), respectively. Predictions of mortality reduction for people who received annual, biennial, and triennial screening regimes compared with controls were 26% (95% CI, 0-50%), 23% (95% CI, 0-48%), and 21% (95% CI, 0-47%), respectively. The efficacy of selective colorectal carcinoma screening has been demonstrated in this study. A high preclinical CRC incidence rate also suggests that such a screening strategy might be cost-effective for countries with intermediate or low incidence of CRC. Methods proposed in this study can be used to evaluate the efficacy of CRC screening in similar screening trials.

A simulation‐based approach to radar backscatter from the sea surface

A numerical procedure for simulating electromagnetic scattering from the sea surface is presented. The simulation scheme is based on a physical model of the sea surface; the surface is generated starting from its two‐dimensional directional spectrum. The scattered electromagnetic field is evaluated by resorting to a two‐scale electromagnetic model. Physical parameters can be taken into account in simulations, as for instance, the local wind velocity direction and strength. The procedure is applied to the case of real aperture radar systems operating at low and intermediate incidence angles. In order to demonstrate the effectiveness of the simulation technique proposed, numerical results are presented and compared with experimental data available in the literature.