A modified two temperature molecular dynamics (2T-MD) model for cascades.

Two-Temperature molecular dynamics (2T-MD) is a common approach for describing how electrons contribute to the evolution of a damage cascade by addressing their role in the redistribution of energy in the system. However, inaccuracies in 2T-MD's treatment of the high-energy particles have limited its utilisation. Here, we propose a reformulation of the traditional 2T-MD scheme to overcome this limitation by addressing the spurious double-interaction of high-energy atoms with electrons. We conduct a series of radiation damage cascades for 30, 50, and 100 keV primary knock-on atoms in increasingly large cubic W cells. In the simulations, we employ our modified 2T-MD scheme along with other treatments of electron-phonon coupling to explore their impact on the cascade evolution and the number of remnant defects. The results suggest that with the proposed modification, 2T-MD simulations account for the temperature time evolution during the ballistic phase and remove arbitrary choices, thus providing a better description of the underlying physics of the damage process.

Relation between image charge and potential alignment corrections for charged defects in periodic boundary conditions.

Charged defects are often studied within the periodic density functional theory (DFT), but this introduces strong finite-size artifacts. In this work, we develop an electrostatic image interaction correction (IIC) method based on the direct solution of the Poisson equation for charge models constructed directly from DFT calculations. These IICs are found to be detail-insensitive, depending almost entirely on bulk dielectric properties. As these IICs are not able to fully explain the observed finite-size scaling, we explore potential alignment in detail and introduce a novel decomposition to separate out different contributions. We find that the two main sources of potential alignment are defect image interactions and changes in the number of atoms present in the supercell. This first effect is accurately predicted by the periodic part of our IIC. The second contribution is unrelated to the IIC and justifies the common observation that the magnitude of finite-size dependence can strongly vary between vacancy and interstitial defects. It can be approximately predicted using atomic radius, but is strongly sensitive to the pseudopotential employed. Combined, these developments provide a new justification for known finite-size scaling rules. Our results suggest that for cubic supercells, the Lany-Zunger IIC, combined with simplified potential alignment between neutral systems, can yield accurate corrections in spite of the simplicity of the approach.

Within-season dynamics of red palm mite (Raoiella indica) and phytoseiid predators on two host palm species in south-west India.

Field surveys were conducted monthly between December 2008 and July 2009 in Kerala, south-west India to compare the population dynamics of the red palm mite Raoiella indica (RPM) on two host plants Areca catechu and Cocos nucifera during one non-monsoon season when, in general, RPM populations increase. The aim was to examine the effects of host plant, host plant locality and the impact of climatic factors on RPM and related phytoseiid predators. There were significantly higher RPM densities on areca in peak season (May/June) compared to coconut; although significantly more coconut sites were infested with RPM than areca. Although no one climatic factor was significantly related to RPM numbers, interactions were found between temperature, humidity and rainfall and the partitioning of host plant locality showed that where conditions were warmer and drier, RPM densities were significantly higher. Specifically on coconut, there was a significant relation between RPM densities and the combined interaction between site temperature, site humidity and phytoseiid densities. There was a marked difference in the density of phytoseiids collected between areca and coconut palms, with significantly more on the latter, in several months. Amblyseius largoensis was the most commonly collected phytoseiid in association with RPM, although Amblyseius tamatavensis species group and Amblyseius largoensis species group were collected in association with RPM also. There was also evidence of a weak numerical response of the combined phytoseiid complex in relation to RPM density the previous month on coconut but this was not observed on areca.

A theoretical study of intrinsic point defects and defect clusters in magnesium aluminate spinel.

Point and small cluster defects in magnesium aluminate spinel have been studied from a first principles viewpoint. Typical point defects that occur during collision cascade simulations are cation anti-site defects, which have a small formation energy and are very stable, O and Mg split interstitials and vacancies. Isolated Al interstitials were found to be energetically unfavourable but could occur as part of a split Mg-Al pair or as a three atom-three vacancy Al 'ring' defect, previously observed in collision cascades using empirical potentials. The structure and energetics of the defects were investigated using density functional theory (DFT) and the results compared to simulations using empirical fixed charge potentials. Each point defect was studied in a variety of supercell sizes in order to ensure convergence. It was found that empirical potential simulations significantly overestimate formation energies, but that the type and relative stability of the defects are well predicted by the empirical potentials both for point defects and small defect clusters.

Comparative studies on populations of Pauesia juniperorum (Hymenoptera: Braconidae), a biological control agent for Cinara cupressivora (Hemiptera: Aphididae).

Pauesia juniperorum (Starý), a solitary endoparasitoid which attacks several Cinara spp. in the subgenus Cupressobium, was introduced into Africa for the control of the cypress aphid Cinara cupressivora Watson & Voegtlin (previously identified as Cinara cupressi (Buckton)) and is now established. Data on its biology including a comparison of populations from different hosts and geographical locations are presented. From the UK this consisted of populations reared from Cinara cupressivora, Cinara fresai Blanchard and Cinara juniperi De Geer, and from France, Cinara ?fresai. Between different populations, the duration of development varied within a narrow range (15.5-18.1 days) at 22 degrees C. Data on duration of development over a range of temperatures (15-26 degrees C) for two populations, from the UK and France ranged between 14.0-31.4 days for males and 14.7-32.8 days for females. The threshold temperature for development was 6.2 degrees C and 4.1 degrees C for the populations from the UK and France, respectively. The mean egg load for different populations ranged between 46.4 and 78.5 eggs. The host species had a significant effect on egg load which was directly related to size of the respective host aphids. The lowest egg load was recorded on specimens reared from C. cupressivora which was the smallest aphid. The population from the UK had a higher intrinsic rate of increase (0.232) than the one from France (0.207).

Online sales: profit without question.

OBJECTIVES: To examine the ease with which underage smokers can purchase cigarettes online using money orders and to evaluate the effectiveness of internet filtering programs in blocking access to internet cigarette vendors (ICVs). DESIGN: Four young people purchased 32 money orders using 32 different names to buy one carton of cigarettes for each named individual. Each money order was subsequently mailed to a different ICV in the USA. No age related information accompanied these online orders. Two internet filtering programs ("Bess" and filtertobacco.org) were tested for their relative efficacy in blocking access to ICV sites. RESULTS: Of the 32 orders placed, four orders never reached the intended ICV. Of the remaining 28 orders, 20 (71%) were filled despite a lack of age verification. Only four (14%) of the orders received were rejected because they lacked proof of age. "Bess" blocked access to 84% and filtertobacco.org to 94% of the ICV sites. CONCLUSIONS: Although underage smokers can easily purchase cigarettes online using money orders, access to these sites can be largely blocked if appropriate filtering devices are installed.

A comparison of the Ameroid constrictor versus ligation in the surgical management of single extrahepatic portosystemic shunts.

Twenty-two dogs were managed surgically for a single extrahepatic portosystemic shunt; 12 with surgical ligation and 10 with an Ameroid constrictor. Utilization of the Ameroid constrictor significantly decreased surgery time to approximately half that of the ligation technique. A decreased intraoperative and postoperative complication rate was noted with the Ameroid constrictor group. Follow-up evaluation demonstrated comparable efficacy when comparing surgical techniques. The Ameroid constrictor offered a surgical occlusion technique for management of a single extra-hepatic portosystemic shunt that was equally effective to ligation while shortening surgical time and minimizing the risks that are commonly associated with ligation of the shunting vessel.

Effects of ring diameter and wire tension on the axial biomechanics of four-ring circular external skeletal fixator constructs.

OBJECTIVE: To determine relative effects of ring diameter and wire tension on axial biomechanical properties of 4-ring circular external skeletal fixator constructs. SAMPLE POPULATION: 4-ring circular external skeletal fixator constructs and artificial bone models. PROCEDURE: 4-ring constructs were assembled, using 50-, 66-, 84-, or 118-mm-diameter rings. Two 1.6-mm-diameter fixation wires were attached to opposing surfaces of each ring at intersection angles of 90 degrees and placed through a gap-fracture bone model. Three examples of each construct were loaded in axial compression at 7 N/s to a maximum load of 400 N at each of 4 wire tensions (0, 30, 60, and 90 kg). Response variables were determined from resulting load-displacement curves (construct stiffness, load at 1 mm of displacement, displacement at 400 N). RESULTS: Ring diameter and wire tension had a significant effect on all response variables and had a significant interaction for construct stiffness and displacement at 400 N. Significant differences within all response variables were seen among all 4 ring diameters and all 4 wire tensions. As ring diameter increased, effect of increasing wire tension on gap stiffness and gap displacement at 400 N decreased. Ring diameter had a greater effect than wire tension on all response variables. CONCLUSIONS AND CLINICAL RELEVANCE: Although effects of wire tension decrease as ring diameter increases, placing tension on wires in larger ring constructs is important because these constructs are inherently less stiff. The differential contribution of ring diameter, wire tension, and their interactions must be considered when using circular external skeletal fixators.

Electrocardiographic findings in dogs with motor vehicle-related trauma.

Motor vehicle-related injury is the most common form of trauma incurred by dogs, and cardiac arrhythmias are a well-recognized complication. Although posttraumatic arrhythmias are often observed, little is known regarding their frequency. This study utilized continuous ambulatory electrocardiography (i.e., Holter monitoring) to describe the cardiac rhythm disturbances in 30 dogs sustaining trauma in motor vehicle accidents. Ventricular ectopy was identified by Holter monitoring in 29 of 30 dogs, although the initial electrocardiogram (EKG) only documented ventricular ectopic complexes (VECs) in four dogs. Ventricular ectopy was infrequent in most dogs (i.e., 62% of the dogs had less than 100 VECs per day for the entire study), but 16% developed frequent arrhythmias (greater than 4,000 VECs per day). In all cases, the VECs were observed within 24 hours of injury. Forty-three percent of dogs had at least one episode of ventricular tachycardia, including several dogs that had an overall infrequent rate of VECs (i.e., less than 100 or 100 to 1,000 VECs per day). Although baseline EKGs are useful in identifying arrhythmias in most dogs, the length of the recording should be increased to improve the likelihood of observing an abnormal EKG event. Most importantly, additional EKGs should be obtained or continuous EKG monitoring should be performed in dogs that display clinical signs that could be attributed to ventricular arrhythmias.

The New Stories/New Cultures after-school enrichment program: a direct cultural intervention.

This article describes the organization, curriculum, and outcomes for New Stories/New Cultures, an activity-based program for after-school enrichment in five schools in the low-income neighborhood near a major American university. The program encourages students (70% Hispanic-American, 30% African-American) to experience themselves as producers of culture, not just as consumers. Its methods include (a) creative team use of video equipment and other expressive media and (b) lessons about media literacy (i.e., making critical choices about images and activities depicted in popular culture and commercials). Outcome measures with the cohort of fifth and sixth graders support the programs occupation-based philosophy. They show that students are more likely to experience themselves as building skills when engaged in activities that are both challenging and enjoyable. The students reported greatest engagement and enjoyment in activities that were creative, team-based, and involving media production. These same activities were correlated with increased self-esteem. The term direct cultural intervention is used to describe the application of occupational principles and critical perspectives to provide a population with conceptual tools and skills for interpreting and successfully navigating the social world.

The impact of anemia correction on cardiovascular disease in end-stage renal disease.

Cardiovascular disease is a major cause of mortality and morbidity in patients with end-stage renal disease. Anemia, a result of erythropoietin deficiency, is associated with increased all-cause and cardiovascular mortality in this population, and predisposes patients to the development of symptomatic heart disease. Anemia is also associated with the development and progression of left ventricular echocardiographic disorders, which strongly predict cardiac failure and death. Left ventricular dilatation with compensatory hypertrophy, the major pattern of echocardiographic disease progression in hemodialysis patients, is a particularly strong predictor of late mortality. Partial correction of anemia with recombinant human erythropoietin likely reduces left ventricular mass and volume. Complete correction of anemia may prevent progressive left ventricular dilatation in patients with normal left ventricular volumes. A recent trial, however, reports excess mortality and vascular access loss in patients with preexisting symptomatic heart disease when anemia was completely corrected. Consequently, hematocrit target ranges above 32% to 36% cannot be recommended in this population. In patients without symptomatic heart disease, it is not possible to conclude that potential benefits derived from a normalized hematocrit will outweigh potential risks.

Preaching to the choir: preference for female-controlled methods of HIV and sexually transmitted disease prevention.

OBJECTIVES: This study assessed interest in female-controlled methods of HIV and sexually transmitted disease (STD) prevention. METHODS: Surveys were conducted with 168 African American women, aged 18 to 32 years, who had had unprotected sex and at least 3 sexual partners in the last 2 years. RESULTS: Of 44 potential features, "female control" (where women control the method by either wearing or applying it) ranked 22nd in average importance. Women who rated female control as highly important had fewer sex partners and fewer STDs and were more likely to use existing prevention methods frequently. CONCLUSIONS: Female control may be of less interest to women most at risk for HIV and other STDs. This underscores the need to take the priorities and preferences of women into consideration when developing new prevention methods.

Subliminal mere exposure: specific, general, and diffuse effects.

The present research examined the possibility that repeated exposure may simultaneously produce specific and diffuse effects. In Study 1, participants were presented with 5-ms exposures of 25 stimuli each shown once (single-exposure condition) or with five repetitions of 5 stimuli (repeated-exposure condition). Participants in the repeated-exposure condition subsequently rated their own mood more positively than those in the single-exposure condition. Study 2 examined whether affect generated by subliminal repeated exposures transfers to unrelated stimuli. After a subliminal exposure phase, affective reactions to previously exposed stimuli, to new but similar stimuli, and to stimuli from a different category were obtained. Previously exposed stimuli were rated most positively and novel different stimuli least positively. All stimuli were rated more positively in the repeated-exposure condition than in the single-exposure condition. These findings suggest that affect generated by subliminal repeated exposure is sufficiently diffuse to influence ratings of unrelated stimuli and mood.

Erythropoietin therapy in chronic uremia: the impact of normalization of hematocrit.

The target hematocrit to be achieved when treating anemia in hemodialysis patients with erythropoietin is controversial. Current evidence-based recommendations suggest a target hematocrit range of 33% to 36%. Small studies suggest that normalization of hematocrit with erythropoietin may benefit hemodialysis patients in terms of brain function, physical performance, quality of life, and prevention of progressive left ventricular dilatation. However a recent study of the effects of erythropoietin-induced normalization of hematocrit in hemodialysis patients with symptomatic heart disease has shown an increase in both mortality and the rate of vascular access thrombosis. Currently, normalization of hematocrit in patients with symptomatic heart disease is not recommended, nor is it possible to conclude that possible benefits of normalization of hematocrit will outweigh risks in hemodialysis patients without symptomatic heart disease.

Ethnicity and attitudes towards life sustaining technology.

The ethical and legal implications of decisions to withhold and withdraw life support have been widely debated. Making end-of-life decisions is never easy, and when the cultural background of doctor and patient differ, communication about these issues may become even more difficult. In this study, we examined the attitudes of people aged 65 and older from different ethnic groups toward foregoing life support. To this end, we conducted a survey of 200 respondents from each of four ethnic groups: European-American, African-American, Korean-American and Mexican-American (800 total), followed by in-depth ethnographic interviews with 80 respondents. European-Americans were the least likely to both accept and want life-support (p < 0.001). Mexican-Americans were generally more positive about the use of life-support and were more likely to personally want such treatments (p < 0.001). Ethnographic interviews revealed that this was due to their belief that life-support would not be suggested if a case was truly hopeless. Compared to European-Americans, Korean-Americans were very positive regarding life-support (RR = 6.7, p < 0.0001); however, they did not want such technology personally (RR = 1.2, p = 0.45). Ethnographic interviews revealed that the decision of life support would be made by their family. Compared to European-Americans, African-Americans felt that it was generally acceptable to withhold or withdraw life-support (RR = 1.6, p = 0.06), but were the most likely to want to be kept alive on life-support (RR = 2.1, p = 0.002). Ethnographic interviews documented a deep distrust towards the health care system and a fear that health care was based on one's ability to pay. We concluded that (a) ethnicity is strongly related to attitudes toward and personal wishes for the use of life support in the event of coma or terminal illness, and (b) this relationship was complex and in some cases, contradictory.

Radiographic evaluation of elbow joints before and after surgery in dogs with possible fragmented medial coronoid process.

OBJECTIVE: To determine the usefulness of 5 radiographic projections of the elbow joint for identification of fragmented coronoid process (FCP) and associated secondary degenerative changes in dogs. DESIGN: Longitudinal clinical study. ANIMALS: 19 dogs suspected of having FCP (7 dogs, 1 elbow joint; 12 dogs, both elbow joints). PROCEDURE: 5 radiographic projections were obtained before and after surgery for all elbow joints on which exploratory arthrotomy was performed because of suspected FCP. Radiographs obtained before surgery were compared with radiographs obtained after surgery and radiographs taken of the excised fragments. Each projection was evalated for its utility in definitively identifying FCP and 7 specific degenerative changes. Interevaluator agreement, use of each radiographic projection for definitively identifying a feature, and ability of the 4 evaluators to definitively identify a feature were analyzed. RESULTS: The craniolateral-caudomedial oblique (Cr15L-CdMO) projection had a significantly higher sensitivity for definitively identifying FCP, compared with the other 4 projections. Interevaluator and kappa agreement for the 5 projections did not differ significantly among the 7 degenerative changes evaluated. The radiographic projection with the highest sensitivity and specificity for detection of a particular degenerative change varied by feature. CLINICAL IMPLICATIONS: Of the 5 radiographic projections evaluated, the Cr15L-CdMO projection provided the highest sensitivity and was the best projection to use for definitively identifying FCP. The craniocaudal, Cr15L-CdMO, and mediolateral projections most reliably allowed for identification of secondary degenerative changes.

Effect of radiographic positioning on interpretation of cubital joint congruity in dogs.

OBJECTIVE: To ascertain effects of x-ray beam centering and limb position on apparent congruity of a normal cubital joint (elbow). ANIMALS: 6 skeletally mature male Treeing Walker Coonhounds without physical, radiographic, or gross evidence of elbow abnormalities. PROCEDURE: Relative movement among humerus, radius, and ulna and measured joint space width on mediolateral and craniocaudal radiographic views was compared, using various x-ray beam centering and limb positions. RESULTS: Highest agreement and greatest certainty on subjective determination of congruity was for the flexed 90 degrees mediolateral radiographic view with the x-ray beam centered on the elbow. Distortion artifact of the proximal ulnar measurements was significant when the x-ray beam was centered on the midpoint of the radius. On the mediolateral view, the humeroradial joint space became significantly wide when the elbow was flexed. On the craniocaudal view, maximal humeroradial joint space width was obtained when the x-ray beam bisected the angle of the joint or was angled +30 degrees toward the humerus. CONCLUSIONS: Artifact distortion of joint width affected objective and subjective assessment of elbow congruity when the limb was placed in extreme flexion or extension or when the x-ray beam was not centered over the area of interest. Optimal visualization of the humeroradial joint space on the craniocaudal view was achieved when the x-ray beam bisected the angle of the elbow or was slightly angled toward the humerus. CLINICAL RELEVANCE: Elbow congruity was best assessed on the flexed 90 degrees lateral radiographic view with the x-ray beam centered on the joint.

A discourse of relationships in bioethics: patient autonomy and end-of-life decision making among elderly Korean Americans.

A two-year, multidisciplinary study (N = 800) was conducted on attitudes about end-of-life decision making among elderly individuals in four ethnic groups (African American, European American, Korean American, and Mexican American). On a quantitative survey, Korean Americans reported negative attitudes about the use of life-sustaining technology for themselves but positive attitudes about its use in general. This article reports on an interview with a 79-year-old typical Korean American respondent to explain the contradiction in the survey data. Expectations among elderly Korean Americans include protecting family members with a life-threatening illness from being informed of their diagnosis and prognosis, and doing everything to keep them alive. Two conclusions, one substantive and the other methodological, are drawn: First, the bioethics discourse on individual rights (patient autonomy) is insufficient to explain the preferences of many Korean Americans and must be supplemented with a discourse on relationships. Second, the rigorous use of qualitative, narrative methods clarifies quantitative data and should not be dismissed as "anecdotal."

Osteosarcoma following total hip arthroplasty in a dog.

Osteosarcoma involving the distal right femur was diagnosed in a nine-year-old female neutered Rottweiler seven years after total hip arthroplasty had been performed on that limb. The findings were consistent with a primary bone tumour and pathological fracture of the right femoral condyle with loosening of the orthopaedic implant and fracture of the polymethylmethacrylate at the distal aspect of the femoral component. Possible hypotheses to explain the association of osteosarcoma with total hip arthroplasty suggest that the neoplastic process was the result of some derangement of host tissue and the healing process or that the implants or their by-products were carcinogenic. Given the large number of total hip arthroplasties that are routinely performed in dogs, the development of a malignant lesion appears to be an extraordinary complication and may be completely coincidental.