Debye screening in single-molecule carbon nanotube field-effect sensors

Point-functionalized carbon nanotube field-effect transistors can serve as highly sensitive detectors for biomolecules. With a probe molecule covalently bound to a defect in the nanotube sidewall, two-level random telegraph noise (RTN) in the conductance of the device is observed as a result of a charged target biomolecule binding and unbinding at the defect site. Charge in proximity to the defect modulates the potential (and transmission) of the conductance-limiting barrier created by the defect. In this Letter, we study how these single-molecule electronic sensors are affected by ionic screening. Both charge in proximity to the defect site and buffer concentration are found to affect RTN amplitude in a manner that follows from simple Debye length considerations. RTN amplitude is also dependent on the potential of the electrolyte gate as applied to the reference electrode; at high enough gate potentials, the target DNA is completely repelled and RTN is suppressed.

The meaning and measurement of implementation climate

Background

Climate has a long history in organizational studies, but few theoretical models integrate the complex effects of climate during innovation implementation. In 1996, a theoretical model was proposed that organizations could develop a positive climate for implementation by making use of various policies and practices that promote organizational members' means, motives, and opportunities for innovation use. The model proposes that implementation climate--or the extent to which organizational members perceive that innovation use is expected, supported, and rewarded--is positively associated with implementation effectiveness. The implementation climate construct holds significant promise for advancing scientific knowledge about the organizational determinants of innovation implementation. However, the construct has not received sufficient scholarly attention, despite numerous citations in the scientific literature. In this article, we clarify the meaning of implementation climate, discuss several measurement issues, and propose guidelines for empirical study.

Discussion

Implementation climate differs from constructs such as organizational climate, culture, or context in two important respects: first, it has a strategic focus (implementation), and second, it is innovation-specific. Measuring implementation climate is challenging because the construct operates at the organizational level, but requires the collection of multi-dimensional perceptual data from many expected innovation users within an organization. In order to avoid problems with construct validity, assessments of within-group agreement of implementation climate measures must be carefully considered. Implementation climate implies a high degree of within-group agreement in climate perceptions. However, researchers might find it useful to distinguish implementation climate level (the average of implementation climate perceptions) from implementation climate strength (the variability of implementation climate perceptions). It is important to recognize that the implementation climate construct applies most readily to innovations that require collective, coordinated behavior change by many organizational members both for successful implementation and for realization of anticipated benefits. For innovations that do not possess these attributes, individual-level theories of behavior change could be more useful in explaining implementation effectiveness.

Summary

This construct has considerable value in implementation science, however, further debate and development is necessary to refine and distinguish the construct for empirical use.

Adjuvant capecitabine and oxaliplatin for gastric cancer: Results of the phase III CLASSIC trial

LBA4002

Background: Surgical resection is a recommended treatment for operable gastric cancer (GC) in general, despite high recurrence rates (40%–80%). Adjuvant chemotherapy aims to reduce recurrences; however, there is currently no universally accepted adjuvant regimen for GC. Methods: CLASSIC is a randomized, open-label, multicenter, international (South Korea, China, and Taiwan) study of XELOX (capecitabine 1000mg/m2 bid, d1–14, q3w and oxaliplatin 130mg/m2, d1, q3w x 8 cycles) vs observation, following D2 gastrectomy. Eligible patients were chemotherapy- and radiotherapy-naive, with stage II (T2N1, T1N2, T3N0), IIIa (T3N1, T2N2, T4N0), or IIIb (T3N2) GC resected within 6 weeks prior to randomization. The primary endpoint is 3-year disease-free survival (DFS). A sample size of 512 patients per arm was planned to observe the 385 DFS events required to provide 80% power at a 5% significance level for the hypothesized treatment effect (hazard ratio [HR] 0.75). The Independent Data Monitoring Committee recommended full evaluation and reporting of results following a positive pre-planned interim analysis at 266 events. Results: The XELOX and observation arms (ITT populations of 520 and 515 patients, respectively) were well balanced for baseline characteristics. The median duration of follow-up was 34.4 (16–51) months. XELOX-related grade 3/4 adverse events (AEs) occurred in 244/496 patients (49%) of the safety population. Neutropenia was the only AE observed in >10% of patients (21%, n=106/496). Serious XELOX-related grade 3/4 AEs occurred in 34/496 patients (7%). There were 62/496 (13%) and 80/476 (17%) deaths on study in the safety populations of XELOX and observation arms, respectively, mostly due to disease progression. Efficacy results in the ITT population are summarized below. Conclusions: This study demonstrates the superior efficacy of adjuvant XELOX vs observation alone following D2 gastrectomy. Although OS data are still immature, there is a trend towards superiority of XELOX. These data support the use of adjuvant XELOX for GC.

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Modifiable and fixed factors predicting quality of life in people with colorectal cancer

Background:

People with colorectal cancer have impaired quality of life (QoL). We investigated what factors were most highly associated with it.

Methods:

Four hundred and ninety-six people with colorectal cancer completed questionnaires about QoL, functioning, symptoms, co-morbidity, cognitions and personal and social factors. Disease, treatment and co-morbidity data were abstracted from case notes. Multiple linear regression identified modifiable and unmodifiable factors independently predictive of global quality of life (EORTC-QLQ-C30).

Results:

Of unmodifiable factors, female sex (P<0.001), more self-reported co-morbidities (P=0.006) and metastases at diagnosis (P=0.036) significantly predicted poorer QoL, but explained little of the variability in the model (R²=0.064). Adding modifiable factors, poorer role (P<0.001) and social functioning (P=0.003), fatigue (P=0.001), dyspnoea (P=0.001), anorexia (P<0.001), depression (P<0.001) and worse perceived consequences (P=0.013) improved the model fit considerably (R²=0.574). Omitting functioning subscales resulted in recent diagnosis (P=0.002), lower perceived personal control (P=0.020) and travel difficulties (P<0.001) becoming significant predictors.

Conclusion:

Most factors affecting QoL are modifiable, especially symptoms (fatigue, anorexia, dyspnoea) and depression. Beliefs about illness are also important. Unmodifiable factors, including metastatic (or unstaged) disease at diagnosis, have less impact. There appears to be potential for interventions to improve QoL in patients with colorectal cancer.

Exploring the limits of ultrafast polymerase chain reaction using liquid for thermal heat exchange: A proof of principle

Thermal ramp rate is a major limiting factor in using real-time polymerase chain reaction (PCR) for routine diagnostics. We explored the limits of speed by using liquid for thermal exchange rather than metal as in traditional devices, and by testing different polymerases. In a clinical setting, our system equaled or surpassed state-of-the-art devices for accuracy in amplifying DNA∕RNA of avian influenza, cytomegalovirus, and human immunodeficiency virus. Using Thermococcus kodakaraensis polymerase and optimizing both electrical and chemical systems, we obtained an accurate, 35 cycle amplification of an 85-base pair fragment of E. coli O157:H7 Shiga toxin gene in as little as 94.1 s, a significant improvement over a typical 1 h PCR amplification.

Spontaneous, elicited and cued causal attributions in the year following a first myocardial infarction

OBJECTIVES

To assess myocardial infarction (MI) patients' causal beliefs, how they change over time and the effects of different assessment methods.

METHOD

The study used a longitudinal design with a follow-up to 1 year. The participants were 100 MI patients who were recruited within 72 hours of admission. Each participant was interviewed and their causal attributions (spontaneous, elicited and cued) were assessed using four different methods.

RESULTS

'Stress', 'smoking', 'it is in the family', 'eating fatty foods' and 'work' items were the most commonly mentioned causes for the MI at all times of measurement and across all measures. On each occasion 'stress' and 'smoking' were selected as the most important causes and patients made fewer attributions over time. Finally, the attributional assessment method used did not affect type of attributions but fewer attributions were reported using the spontaneous method.

CONCLUSION

Patients do provide causal attributions following an MI. While many are similar to causal factors identified by medicine, patients appear to place more emphasis on 'stress'. As predicted by attribution theory, attributions changed over time. The method of obtaining the attributions does not appear to affect the attributions made but greatly affects their number. While all the methods used have their place, the cued method with a list of possible attributions offers a rich return for effort expended.

Alkalinity conversion of bauxite refinery residues by neutralization

Red mud remains the largest environmental issue for the alumina industry due to its high pH (>13), fine-grained nature (>90% is <10 microm), elevated sodium concentration (>50 g/kg), and soluble alkalinity (approximately 30 g/kg as equivalent CaCO(3)), which reduce the transport and reuse options of red mud. The neutralization of red mud provides potential reuse options because neutralization lowers pH, increases grain-size (e.g., coagulation), and precipitates or converts alkalinity. This paper investigates the geochemistry of 3 treatments of a red mud to affect neutralization and potentially convert materials from a waste material to a resource. This study investigates two commonly used neutralization techniques, a CO(2)-neutralized red mud (CNRM), a Basecon-neutralized red mud (Basecon), and a more novel approach of a CO(2)-neutralization followed by a Basecon-neutralization (Hybrid) to understand the effects that these treatments have on neutralization process. Data indicate that the neutralization techniques form two distinct geochemical groups when discriminated on total alkalinity alone, that is treatments with, and treatments without alkalinity precipitation. However, each treatment has distinct alkalinity speciation (hydroxide-dominant or carbonate/bicarbonate dominant) and residual Ca, Mg and Al in the treatment solution. Similarly, solids produced differ in their reaction pH and ANC, and contrary pH and ANC, a contrary to other studies, Dawsonite was not seen to precipitate during any neutralization. However, despite this approximately 17 g/kg CO(2) was sequestered during CNRM and hybrid neutralizations and all treatments increased either the transport or reuse options of red mud in some way.

Enterocutaneous fistula: a single-centre experience

BACKGROUND

Enterocutaneous fistulae (ECFs) present a difficult management problem and can cause significant morbidity. The aim of the study was to assess the outcome of these patients.

METHODS

A retrospective chart review of all patients with ECF managed at a tertiary centre between 1996 and 2006 was performed. Demographic, management and outcome data including ECF closure, morbidity and mortality were recorded.

RESULTS

A total of 33 patients (17 male) were identified with ECF (median age: 63 years, range: 27-84). The primary aetiology was Crohn's (30%), anastomotic leak (24%), iatrogenic (18%), mesh (6%), neoplasia (6%) and other (16%). Definitive surgery was undertaken in 21 (64%) at a median of 6.4 months (0.4-72 range) following presentation. Twenty percent of patients required emergency surgical intervention and 5 patients required preoperative total parenteral nutrition (TPN). Surgical management was formal resection and reanastomosis in all patients, with a mean operative time of 4.75 h (standard deviation = 1.8). The median hospital stay for the operative group was 19 days (7-85). Four patients required post-operative TPN with one patient requiring home TPN. Fistula closure rate was 97% (operative group: 21 out of 21; non-operative group: 11 out of 12). Mean follow-up was 37.3 months (0.5-217). Six (19%) operative patients developed fistula recurrence. There were two deaths at 2 and 5 months (fistula aetiology malignant colonic fistula and radiation enteritis, respectively).

CONCLUSION

Patients with ECF can be treated with low morbidity and low recurrence rate in a multidisciplinary setting. We believe that patients with ECF should be referred to specialist units for management.

The Terry Fox Research Institute’s Atlantic Dialogue on Patient-Centred Care in a Personalized Treatment World

The words “personalized medicine” are used daily now in cancer care and research conversations. But what do those words really mean to us as patients, caregivers, physicians, managers of the health system, or researchers? Do we know how personalized medicine will affect us over the next decade? Are we prepared?Those and other questions are part of a continuing conversation that the Terry Fox Research Insti-tute is having with the Canadian public in 2010 as part of its public research and outreach project, The Pan-Canadian Dialogue Series on Cancer: Let’s Get Personal. The first dialogue was held in St. John’s, Newfoundland and Labrador, April 12, to coincide with the 30th anniversary of the Terry Fox Marathon of Hope. It featured speakers and panellists from Newfoundland and Labrador, Nova Scotia, New Brunswick, and Prince Edward Island. Three core issues framed the Atlantic discussion: cancer and population health, cancer and the health system, and the science behind cancer care.

D-dimer testing in pregnant patients: towards determining the next 'level' in the diagnosis of deep vein thrombosis

SUMMARY BACKGROUND

The role of D-dimer in excluding deep vein thrombosis (DVT) in pregnancy is currently uncertain. We hypothesized that the specificity of sensitive D-dimer assays could be improved without compromising sensitivity by using higher D-dimer cut-off values.

OBJECTIVE

To determine the test characteristics of two rapid enzyme-linked immunosorbent assays and three latex agglutination assays in pregnancy.

METHOD

We recruited consecutive pregnant women who presented to participating centers with suspected DVT for the study. Symptomatic women were investigated with compression ultrasonography, and received 3 months of clinical follow-up to assess for the presence of venous thrombosis. Plasma samples for D-dimer were collected and frozen at the time of presentation. The median and mean D-dimer values for respective trimesters of pregnancy in patients with and without DVT were calculated. Receiver operating curves (ROCs) were plotted for respective assays to establish the best cut-points. The test characteristics corresponding to standard cut-points and these 'pregnancy' cut-points are presented.

RESULTS

The prevalence of DVT in our cohort was 6.6% (95% confidence interval 4.0-10.6%). The mean and median D-dimer values were significantly increased throughout pregnancy. Overall, women with confirmed DVT had higher D-dimer levels than women without DVT (P < 0.0001). Improved specificities (62-79%) were observed with the use of higher cut-points obtained from ROCs for all five assays, and high sensitivities were maintained (80-100%) for DVT diagnosis.

CONCLUSION

Using higher cut-points than those used in non-pregnant patients, the specificity of D-dimer assays for the diagnosis of DVT in pregnancy can be improved without compromising sensitivity. Validation in prospective management studies is needed.

Comparison of the anticoagulant intensities of fondaparinux and enoxaparin in the Organization to Assess Strategies in Acute Ischemic Syndromes (OASIS)-5 trial

BACKGROUND

In the OASIS-5 trial, fondaparinux reduced major bleeding with similar short-term efficacy as enoxaparin but lowered death and stroke during long-term follow-up. The mechanism of lower bleeding and improved efficacy with fondaparinux is uncertain.

METHODS AND RESULTS

We compared the anti-Xa concentration (reflecting drug levels), Xa clot time (reflecting anticoagulant effect) and endogenous thrombin potential (ETP; a global test of hemostatic function) in plasma samples collected 6, 24 and 72 h after the first dose of the study drug in 48 patients randomly assigned fondaparinux 2.5 mg day(-1) and 42 patients assigned enoxaparin 1 mg kg(-1) twice daily in the OASIS-5 trial. Patients assigned to fondaparinux compared with enoxaparin had a significantly lower mean anti-Xa level [0.52 IU mL(-1) (SD 0.22 IU mL(-1)) vs. 1.2 IU mL(-1) (SD 0.45 IU mL(-1)), P<0.0001] and Xa clot time [64.9 s (SD 17.7 s) vs. 111.8 s (SD 29.6 s), P<0.0001], and significantly higher ETP area under the curve (AUC) [386.7 mA (SD 51.5 mA) vs. 206.4 mA (SD 90.6 mA), P<0.001] at 6 h, and these differences remained evident at 24 and 72 h. There was significantly less variability of the results of anti-Xa levels, Xa clot time and ETP AUC for fondaparinux compared with enoxaparin at 6 h (P<0.001 for each comparison).

CONCLUSION

Fondaparinux 2.5 mg day(-1) compared with enoxaparin 1 mg kg(-1) twice daily produces less variable anticoagulant effect and lower mean anticoagulant intensity. These results most likely explain the reduced risk of bleeding seen with fondaparinux compared with enoxaparin in the OASIS-5 trial and suggest that a lower intensity of anticoagulation than used in the past may be sufficient to prevent recurrent ischemic events and death in patients with ACS who are concurrently treated with aspirin and clopidogrel.

The PRaCTICaL study of nurse led, intensive care follow-up programmes for improving long term outcomes from critical illness: a pragmatic randomised controlled trial

OBJECTIVES

To test the hypothesis that nurse led follow-up programmes are effective and cost effective in improving quality of life after discharge from intensive care.

DESIGN

A pragmatic, non-blinded, multicentre, randomised controlled trial.

SETTING

Three UK hospitals (two teaching hospitals and one district general hospital).

PARTICIPANTS

286 patients aged >or=18 years were recruited after discharge from intensive care between September 2006 and October 2007.

INTERVENTION

Nurse led intensive care follow-up programmes versus standard care. Main outcome measure(s) Health related quality of life (measured with the SF-36 questionnaire) at 12 months after randomisation. A cost effectiveness analysis was also performed.

RESULTS

286 patients were recruited and 192 completed one year follow-up. At 12 months, there was no evidence of a difference in the SF-36 physical component score (mean 42.0 (SD 10.6) v 40.8 (SD 11.9), effect size 1.1 (95% CI -1.9 to 4.2), P=0.46) or the SF-36 mental component score (effect size 0.4 (-3.0 to 3.7), P=0.83). There were no statistically significant differences in secondary outcomes or subgroup analyses. Follow-up programmes were significantly more costly than standard care and are unlikely to be considered cost effective.

CONCLUSIONS

A nurse led intensive care follow-up programme showed no evidence of being effective or cost effective in improving patients' quality of life in the year after discharge from intensive care. Further work should focus on the roles of early physical rehabilitation, delirium, cognitive dysfunction, and relatives in recovery from critical illness. Intensive care units should review their follow-up programmes in light of these results.

TRIAL REGISTRATION

ISRCTN 24294750.

Using the theory of planned behaviour to develop an assessment of attitudes and beliefs towards prosthetic use in amputees

PURPOSE

To develop a questionnaire based on the theory of planned behaviour (TPB) to predict prosthetic use.

METHOD

In part one, 31 amputees over 50 years of age with peripheral arterial disease completed attitude items containing 27 bipolar adjectives and open-ended questions on behavioural, normative and control beliefs relating to using the prosthesis. Academic, clinical and patient experts (n = 12) identified bipolar adjectives with best face validity. In part two, 15 amputees completed three behavioural format questions relating to prosthetic use and were asked to indicate the easiest to answer.

RESULTS

Following the completion of the attitude items by the amputees and the expert panel review, 5 items remained (Cronbach's alpha = 0.87) with corrected item-total correlations ranging from 0.43 to 0.83. Modal behavioural beliefs concerned mobility (46.5%), independence (25.6%) and participation restrictions (16.3%), normative beliefs concerned family (33.3%), NHS staff (31.7%), friends (19.1%) and other patients (15.9%) and control beliefs concerned stairs (21.1%), slippery/rough surfaces (28.9%), disabled facilities (54.8%) and people helping (22.6%). In relation to part 2, an exact numerical report of hours and days of prosthetic use was found easiest to answer (73%).

CONCLUSIONS

Based on this qualitative and quantitative development work, the questionnaire contains five attitude items, six behavioural, eight normative, eight control belief items and two self-report questions of the behaviour.

Unintended changes in cognition, mood, and behavior arising from cell-based interventions for neurological conditions: ethical challenges

The prospect of using cell-based interventions (CBIs) to treat neurological conditions raises several important ethical and policy questions. In this target article, we focus on issues related to the unique constellation of traits that characterize CBIs targeted at the central nervous system. In particular, there is at least a theoretical prospect that these cells will alter the recipients' cognition, mood, and behavior-brain functions that are central to our concept of the self. The potential for such changes, although perhaps remote, is cause for concern and careful ethical analysis. Both to enable better informed consent in the future and as an end in itself, we argue that early human trials of CBIs for neurological conditions must monitor subjects for changes in cognition, mood, and behavior; further, we recommend concrete steps for that monitoring. Such steps will help better characterize the potential risks and benefits of CBIs as they are tested and potentially used for treatment.

Changing clinicians' behavior: a randomized controlled trial of fees and education

The fissure-sealing of newly erupted molars is an effective caries prevention treatment, but remains underutilized. Two plausible reasons are the financial disincentive produced by the dental remuneration system, and dentists' lack of awareness of evidence-based practice. The primary hypothesis was that implementation strategies based on remuneration or training in evidence-based healthcare would produce a higher proportion of children receiving sealed second permanent molars than standard care. The four study arms were: fee per sealant treatment, education in evidence-based practice, fee plus education, and control. A cost-effectiveness analysis was conducted. Analysis was based on 133 dentists and 2833 children. After adjustment for baseline differences, the primary outcome was 9.8% higher when a fee was offered. The education intervention had no statistically significant effect. 'Fee only' was the most cost-effective intervention. The study contributes to the incentives in health care provision debate, and led to the introduction of a direct fee for this treatment.

Manual Detection of Spatial and Temporal Torque Variation through a Rotary Switch

We report three experiments on manual detection of torque variations experienced through a rotary switch. The experiments were designed to investigate whether torque perception was determined by the spatial or by the temporal characteristics of the rotary switch. In Exp. I, manual detection thresholds of torque variation were measured with raised sinusoidal torque profiles that varied in spatial period from 2.8deg to 180deg per cycle. In Exp. II, the same was measured for torque profiles that varied in temporal frequency from 2 to 300 Hz. Exp. III was similar to Exp. 1 except that the participants were required to turn the rotary switch at two different speeds for each of seven spatially specified torque profiles (spatial period: 2.8deg to 90deg per cycle). A comparison of the thresholds obtained in Exp. III and those in Exps. I and II suggests that the detection of torque variations depends on the spatial, not temporal, specification of the torque profiles. Our results can potentially shed new light on the design and engineering specification of rotary switches.