Competing risks, left truncation and late entry effect in A-bomb survivors cohort

The cohort under study comprises A-bomb survivors residing in Hiroshima Prefecture since 1968. After this year, thousands of survivors were newly recognized every year. The aim of this study is to determine whether the survival experience of the late entrants to the cohort is significantly different from the registered population in 1968. Parametric models that account for left truncation and competing risks were developed by using sub-hazard functions. A Weibull distribution was used to determine the possible existence of a late entry effect in Hiroshima A-bomb survivors. The competing risks framework shows that there might be a late entry effect in the male and female groups. Our findings are congruent with previous studies analysing similar populations

Using blind analysis for software engineering experiments

Context: In recent years there has been growing concern about conflicting experimental results in empirical software engineering. This has been paralleled by awareness of how bias can impact research results. Objective: To explore the practicalities of blind analysis of experimental results to reduce bias. Method : We apply blind analysis to a real software engineering experiment that compares three feature weighting approaches with a na ̈ıve benchmark (sample mean) to the Finnish software effort data set. We use this experiment as an example to explore blind analysis as a method to reduce researcher bias. Results: Our experience shows that blinding can be a relatively straightforward procedure. We also highlight various statistical analysis decisions which ought not be guided by the hunt for statistical significance and show that results can be inverted merely through a seemingly inconsequential statistical nicety (i.e., the degree of trimming). Conclusion: Whilst there are minor challenges and some limits to the degree of blinding possible, blind analysis is a very practical and easy to implement method that supports more objective analysis of experimental results. Therefore we argue that blind analysis should be the norm for analysing software engineering experiments

To assess the value of satellite photographs in resource evaluation on a national scale

The author has identified the following significant results. The limit of resolution on ERTS imagery is normally acknowledged to be about 60 miles although very long features such as roads and railways which are often less than 10 miles long are easily detectable. An example is the north-south road and railway from Lobatse to Francistown. Vegetation growth from winter to summer is readily monitored on false color imagery. The limits of government ranches and special farming areas can be quite accurately ascertained from ERTS imagery. Another aspect to which ERTS imagery lends itself is the location and demarcation of bush fires, many of which were seen on the first imagery which was acquired at the end of the cold, dry season. As a whole, MSS 7 offers maximum reflectance contrast among black and white imagery and is the wavelength used most for interpretation

Kant, causation and laws of nature

In the Second Analogy, Kant argues that every event has a cause. It remains disputed what this conclusion amounts to. Does Kant argue only for the Weak Causal Principle that every event has some cause, or for the Strong Causal Principle that every event is produced according to a universal causal law? Existing interpretations have assumed that, by Kant’s lights, there is a substantive difference between the two. I argue that this is false. Kant holds that the concept of cause contains the notion of lawful connection, so it is analytic that causes operate according to universal laws. He is explicit about this commitment, not least in his derivation of the Categorical Imperative in Groundwork III. Consequently, Kant’s move from causal rules to universal laws is much simpler than previously assumed. Given his commitments, establishing the Strong Causal Principle requires no more argument than establishing the Weak Causal Principle

Identifying studies for systematic reviews - An example from medical imaging

Objectives: To determine if published figures on the proportion of articles included in systematic reviews and identified in electronic databases are applicable to an example from medical imaging. Methods: A systematic review was performed. Additionally, sensitivity and precision of a MEDLINE search were compared with values from three published searches, each customized for a specific field. Results: All articles included in the systematic review were in electronic databases. The MEDLINE search had low precision compared with searches in other fields. Conclusions: in a specific area of medical imaging, electronic databases, including MEDLINE, are reliable sources of articles

Costs of publicly provided maternity services in Rosario, Argentina

This material is posted here with permission of the publishers, Instituto Nacional de Salud Pública. Internal or personal use of this material is permitted. However, permission to reprint/republish this material must be obtained from the Publisher.Objective. This study estimates the costs of maternal health services in Rosario, Argentina. Material and Methods. The rovider costs (US$1999) of antenatal care, a normal vaginal delivery and a caesarean section, were evaluated retrospectively in two municipal hospitals. The cost of an antenatal visit was evaluated in two health centres and the patient costs associated with the visit were evaluated in a hospital and a health centre. Results. The average cost per hospital day is$114.62. The average cost of a caesarean section ($525.57) is five times greater than that of a normal vaginal delivery ($105.61). A normal delivery costs less at the general hospital and a c-section less at the aternity hospital. The average cost of an antenatal visit is $31.10. The provider cost is lower at the health centre than at the hospital. Personnel accounted for 72-94$4.70. Direct costs are minimal compared to indirect costs of travel and waiting time. Conclusions. These results suggest the potential for increasing the efficiency of resource use by promoting antenatal care visits at the primary level. Women could also benefit from reduced travel and waiting time. Similar benefits could accrue to the provider by encouraging normal delivery at general hospitals, and complicated deliveries at specialised maternity hospitals.Josephine Borghi is funded by the Department for International Development through the Maternal Health Programme at the London School of Hygiene and Tropical Medicine. This project was conducted for and funded by the Human Reproduction Programme at WHO, Geneva

MODELING OF ULTRASONIC INSPECTION METHODS FOR GENERATION IV REACTORS

The Lead-cooled Fast Reactor (LFR), a prominent category of Generation IV advanced reactors, involves design challenges for reactor plant in-service inspection (ISI) due to high operating temperatures, coolant opacities that prevent visual inspection, and the tendency for coolant corrosive attack. These challenges limit the feasibility and effectiveness of conventional ISI technologies. To overcome these challenges, acoustic methods that can operate under high temperature conditions are being actively considered in the U.S. as well as internationally. This research investigates the application of ultrasonic transducers, either piezoelectric or electro-magnetic, for LFR inspections. COMSOL Multiphysics software is used to model the effectiveness of thickness measurements, defect detections, and acoustic reflectance, for the reactor vessel and components within or in contact with the coolant. Acoustic absorption due to wave propagation through molten lead is also investigated. The models were designed in conjunction with future experimental work to provide comparison data between theory and experiment.Department of Energy, Livermore, CA 94950Outstanding ThesisLieutenant, United States NavyApproved for public release. Distribution is unlimited

Attentional load and sensory competition in human vision: Modulation of fMRI responses by load fixation during task-irrelevant stimulation in the peripheral visual field.

Perceptual suppression of distractors may depend on both endogenous and exogenous factors, such as attentional load of the current task and sensory competition among simultaneous stimuli, respectively. We used functional magnetic resonance imaging (fMRI) to compare these two types of attentional effects and examine how they may interact in the human brain. We varied the attentional load of a visual monitoring task performed on a rapid stream at central fixation without altering the central stimuli themselves, while measuring the impact on fMRI responses to task-irrelevant peripheral checkerboards presented either unilaterally or bilaterally. Activations in visual cortex for irrelevant peripheral stimulation decreased with increasing attentional load at fixation. This relative decrease was present even in V1, but became larger for successive visual areas through to V4. Decreases in activation for contralateral peripheral checkerboards due to higher central load were more pronounced within retinotopic cortex corresponding to 'inner' peripheral locations relatively near the central targets than for more eccentric 'outer' locations, demonstrating a predominant suppression of nearby surround rather than strict 'tunnel vision' during higher task load at central fixation. Contralateral activations for peripheral stimulation in one hemifield were reduced by competition with concurrent stimulation in the other hemifield only in inferior parietal cortex, not in retinotopic areas of occipital visual cortex. In addition, central attentional load interacted with competition due to bilateral versus unilateral peripheral stimuli specifically in posterior parietal and fusiform regions. These results reveal that task-dependent attentional load, and interhemifield stimulus-competition, can produce distinct influences on the neural responses to peripheral visual stimuli within the human visual system. These distinct mechanisms in selective visual processing may be integrated within posterior parietal areas, rather than earlier occipital cortex

Soil Survey Circular No. 1: Nitrogen From the Air

Summary1. Nitrogen is necessary for the growth of crops.2. Nitrogen is disappearing from cultivated soils.3. Maintain the nitrogen supply by growing legume crops.a. See to it that the soil is not sour.b. Inoculate the seed.4. Don’t burn stalks or straw, becausea. A ton of wheat straw contains $4 worth of nitrogen.b. A ton of oats straw contains$4.80 worth of nitrogen.c. A ton of corn stalks contains $6.40 worth of nitrogen