Portable Diffuse Reflectance Spectroscopy of Potato Leaves for Pre-Symptomatic Detection of Late Blight Disease

We report on the use of leaf diffuse reflectance spectroscopy for plant disease detection. A smartphone-operated, compact diffused reflectance spectrophotometer is used for field collection of leaf diffuse reflectance spectra to enable pre-symptomatic detection of the progression of potato late blight disease post inoculation with oomycete pathogen Phytophthora infestans. Neural-network-based analysis predicts infection with >96% accuracy, only 24 h after inoculation with the pathogen, and nine days before visual late blight symptoms appear. Our study demonstrates the potential of using portable optical spectroscopy in tandem with machine learning analysis for early diagnosis of plant diseases.

Iteratively seeded mode-locking

Ultrashort pulsed mode-locked lasers enable research at new time-scales and revolutionary technologies from bioimaging to materials processing. In general, the performance of these lasers is determined by the degree to which the pulses of a particular resonator can be scaled in energy and pulse duration before destabilizing. To date, milestones have come from the application of more tolerant pulse solutions, drawing on nonlinear concepts like soliton formation and self-similarity. Despite these advances, lasers have not reached the predicted performance limits anticipated by these new solutions. In this letter, towards resolving this discrepancy, we demonstrate that the route by which the laser arrives at the solution presents a limit to performance which, moreover, is reached before the solution itself becomes unstable. In contrast to known self-starting limitations stemming from suboptimal saturable absorption, we show that this limit persists even with an ideal saturable absorber. Furthermore, we demonstrate that this limit can be completely surmounted with an iteratively seeded technique for mode-locking. Iteratively seeded mode-locking is numerically explored and compared to traditional static seeding, initially achieving a five-fold increase in energy. This approach is broadly applicable to mode-locked lasers and can be readily implemented into existing experimental architectures.

Holographic coherent anti-Stokes Raman scattering bio-imaging

CARS holography captures both the amplitude and the phase of a complex anti-Stokes field, and can perform three-dimensional imaging by digitally focusing onto different depths inside a specimen. The application of CARS holography for bio-imaging is demonstrated. It is shown that holographic CARS imaging of sub-cellular components in live HeLa cells can be achieved.

Preoperative skin antiseptics for preventing surgical wound infections after clean surgery

BACKGROUND

Approximately 15% of elective surgery patients and 30% of patients receiving contaminated or dirty surgery are estimated to develop post-operative wound infections. The costs of surgical wound infection can be considerable in financial as well as social terms. Preoperative skin antisepsis is performed to reduce the risk of post-operative wound infections by removing soil and transient organisms from the skin. Antiseptics are thought to be both toxic to bacteria and aid their mechanical removal. The effectiveness of preoperative skin preparation is thought to be dependent on both the antiseptic used and the method of application, however it is unclear whether preoperative skin antisepsis actually reduces post-operative wound infection and if so which antiseptic is most effective.

OBJECTIVES

To determine whether preoperative skin antisepsis reduces post-operative surgical wound infection.

SEARCH STRATEGY

We searched the Cochrane Wounds Group Specialised Trials Register and the Cochrane Central Register of Controlled Trials in April 2004. In addition we handsearched journals, conference proceedings and bibliographies.

SELECTION CRITERIA

Randomised controlled trials evaluating the use of preoperative skin antiseptics applied immediately prior to incision in clean surgery. There were no restrictions based on language, date or publication status.

DATA COLLECTION AND ANALYSIS

Three reviewers independently undertook data extraction and assessment of study quality. Pooling was inappropriate and trials are discussed in a narrative review.

MAIN RESULTS

We identified six eligible RCTs evaluating preoperative antiseptics. There was significant heterogeneity in the comparisons and the results could not be pooled. In one study, infection rates were significantly lower when skin was prepared using chlorhexidine compared with iodine. There was no evidence of a benefit in four trials associated with the use of iodophor impregnated drapes.

REVIEWERS' CONCLUSIONS

There is insufficient research examining the effects of preoperative skin antiseptics to allow conclusions to be drawn regarding their effects on post-operative surgical wound infections. Further research is needed.

Carotid endarterectomy in symptomatic elderly patients

Fifty-three of 203 consecutive carotid endarterectomies (26%) performed on the Neurosurgical Service at the University of Iowa were in patients over 70 years of age (mean age, 73.4). This series included 38 men and 15 women. Thirty-three patients (62%) presented with transient ischemic attacks, and the remaining 38% were functional stroke patients. Medical risk factors in this group included hypertension in 70%, previous myocardial infarction in 26%, angina in 17%, peripheral vascular disease in 23%, and diabetes in 13%. Sixty-four per cent of the patients had been previously treated with antihypertensive drugs, 43% with antiplatelet agents, and 4% with anticoagulants. Noninvasive vascular evaluation was performed in 25 of 53 (47%) patients, and all underwent angiography before operation. There were no angiographic complications. All patients were operated on with full-channel electroencephalographic (EEG) monitoring. Indwelling shunts were required in 6 of 53 (11%) cases. Intraoperative heparin was given and not reversed; the mean dose was 5100 units. The mean clamp time was 48 minutes. Patch grafts, fashioned from common facial or saphenous veins, were used in 2 patients. Eight patients had contralateral carotid occlusions, but only 2 (25%) required indwelling shunt placement based on EEG criteria. There were no perioperative deaths in this series. One patient had a postoperative stroke, and 1 patient had a postoperative nonfatal myocardial infarction. Transient surgical complications included 3 wound hematomas, 1 wound abscess, and 2 self-limited cranial nerve palsies (13%).(ABSTRACT TRUNCATED AT 250 WORDS)