Towards a comprehensive simulation model of malaria epidemiology and control.

Planning of the control of Plasmodium falciparum malaria leads to a need for models of malaria epidemiology that provide realistic quantitative prediction of likely epidemiological outcomes of a wide range of control strategies. Predictions of the effects of control often ignore medium- and long-term dynamics. The complexities of the Plasmodium life-cycle, and of within-host dynamics, limit the applicability of conventional deterministic malaria models. We use individual-based stochastic simulations of malaria epidemiology to predict the impacts of interventions on infection, morbidity, mortality, health services use and costs. Individual infections are simulated by stochastic series of parasite densities, and naturally acquired immunity acts by reducing densities. Morbidity and mortality risks, and infectiousness to vectors, depend on parasite densities. The simulated infections are nested within simulations of individuals in human populations, and linked to models of interventions and health systems. We use numerous field datasets to optimise parameter estimates. By using a volunteer computing system we obtain the enormous computational power required for model fitting, sensitivity analysis, and exploration of many different intervention strategies. The project thus provides a general platform for comparing, fitting, and evaluating different model structures, and for quantitative prediction of effects of different interventions and integrated control programmes.

Minimally invasive hardware removal after minimally invasive distal radius plate osteosynthesis (MIPO): Feasibility study in a 388 case series.

HYPOTHESIS: The aim of the present study was to assess the technical feasibility of minimally invasive volar plate removal following distal radius fracture. MATERIAL AND METHODS: Three hundred and eighty-eight plates removed from 387 patients (357 females: mean age, 50 years) were assessed retrospectively. The incision used the primary minimally invasive approach and was closed after plate removal by intradermal continuous suture, without drainage or immobilization. RESULTS: Mean scar size was 22.2mm preoperatively, and the incision was 19.8mm at start and 21.4mm at end of procedure, these differences being non-significant. The scar was enlarged by accidental skin tear in 13 cases and intentionally by lancet in 11 cases. There were 29 screw-related complications, 1 bone crack without clinical impact, and 1 plate fracture. There were no postoperative complications. DISCUSSION: The present results demonstrate the feasibility of removing a volar plate on the distal radius via a 20-mm approach. These findings should be confirmed on a future study comparing minimally invasive plate ablation and conventional approaches.

Treatment of unstable distal phalanx fractures by extra-articular DIP pinning: A series of 12 cases.

Unstable distal phalanx fractures are typically treated by pinning of the distal phalanx or the distal interphalangeal joint (DIP). Complications include unstable fixation, K-wire migration, septic arthritis and osteoarthritis. To limit these complications, we wanted to explore the benefits of using locked extra-articular DIP pinning. The cohort consisted of 12 patients (mean age 36.3 years) who had an extra-articular (6 cases) or intra-articular distal phalanx fracture (6 cases). All patients were treated surgically with a construct consisting of two connected K-wires: one was placed inside the shaft of the distal phalanx and the other was placed perpendicular to the middle phalanx. The K-wires were removed after 1 month. After an average follow-up of 19.9 weeks, pain was 0.4/10 and the QuickDASH score was 7.41/100 on average. The range of motion was, on average, 30.0° less than the contralateral uninjured side for active flexion, 8.8° less for active extension, 32.0° less for passive flexion and 4.1° less for passive extension. The overall hand strength averaged 85.2% of the contralateral one. One secondary displacement occurred but there were no infections. In all, these findings suggest that locked extra-articular DIP pinning is a simple and reproducible surgical treatment for distal phalanx fractures. LEVEL OF EVIDENCE: IV.

Support for partial lesions of the flexor tendons of the fingers: a retrospective study of 36 cases.

The treatment of traumatic partial injuries of the flexor tendons of the fingers is seldom published. The only published clinical series states that the therapeutic approach depends on the existence or absence of a preoperative trigger. We hypothesized that the therapeutic attitude mainly depends on the percentage of the injured cross-section. Our retrospective series included 36 partial lesions of 31 fingers in 29 patients. The average age was 42 years, there were 19 men. We noted 8 lesions in zones I, 21 in zone II and 2 in zone III. The average percentage of the injured cross-section was 35% and ranged from 10% to 90%. If the lesion was less than 50% (29 tendons), a tangential resection was performed. If the lesion exceeded 50% (seven tendons), a direct suture was performed, supplemented by a running suture. At a follow-up of 34 months, the average pain on a visual analogue scale was 0.7. The average percentage of strength compared to the contralateral side was 93%. The Quick DASH score was 6.2. The range of motion averaged 214° with extremes ranging from 90° to 260°. We observed no cases of hypertrophic callus, neither through the MRI nor through the ultrasonography. Complications such as trigger finger, pseudoblocage or rupture were not observed. Based on our results, in case of partial injury of a flexor tendon, we propose to perform a tangential resection in cross-section lesions up to 50%, and a suture for those which exceeded 50%.

Long thoracic nerve release for scapular winging: clinical study of a continuous series of eight patients.

UNLABELLED: Scapular winging secondary to serratus anterior muscle palsy is a rare pathology. It is usually due to a lesion in the thoracic part of the long thoracic nerve following violent upper-limb stretching with compression on the nerve by the anterior branch of thoracodorsal artery at the "crow's foot landmark" where the artery crosses in front of the nerve. Scapular winging causes upper-limb pain, fatigability or impotence. Diagnosis is clinical and management initially conservative. When functional treatment by physiotherapy fails to bring recovery within 6 months and electromyography (EMG) shows increased distal latencies, neurolysis may be suggested. Muscle transfer and scapula-thoracic arthrodesis are considered as palliative treatments. We report a single-surgeon experience of nine open neurolyses of the thoracic part of the long thoracic nerve in eight patients. At 6 months' follow-up, no patients showed continuing signs of winged scapula. Control EMG showed significant reduction in distal latency; Constant scores showed improvement, and VAS-assessed pain was considerably reduced. Neurolysis would thus seem to be the first-line surgical attitude of choice in case of compression confirmed on EMG. The present results would need to be confirmed in larger studies with longer follow-up, but this is made difficult by the rarity of this pathology. LEVEL OF EVIDENCE: III.

Prospective continuous study comparing intrafocal cross-pinning HK2(®) with a locking plate in distal radius fracture fixation.

The fixation of distal radius fractures by pinning or locking plates remains controversial. The aim of this prospective continuous study was to compare the results of 28 anterior locking plates with 23 intrafocal cross-pinning HK2(®) systems. The mean age of group I (SVP(®), SBI™ plate) was 61 years. There were 15 extra-articular and 13 articular fractures. The mean age of group II (HK2(®), Arex™) was 63 years, with 13 extra-articular and 10 articular fractures. Twelve clinical variables were measured: pain, wrist strength, supination strength, pronation strength, quick DASH score, range of wrist motion in flexion, extension, pronation, and supination, ulnar variance, radial slope, and radial volar tilt. At 40 weeks follow-up, there was no difference between the two groups for 10 variables; two variables showed differences between the two groups: mean quick DASH score was 10.7 for group I, 19.7 for group II, and mean ulnar variance was -0.95 mm for group I, and 1.16 mm for group II. Six transient complications were noted for group I: five tenosynovitis, and one carpal tunnel syndrome. We noted 12 complications in group II: four superficial infections, two secondary displacements, one pin migration, two CRPS type II, two tendon ruptures and one nerve irritation. Generally, plates provided a more stable fixation associated with less complications while the HK2(®) system was quicker and less costly. The indications for its use need to be refined with a larger series and longer follow-up.

[Midcarpal fusion using break-away compression screw]. / Arthrodèse médiocarpienne par vis-broches à compression.

Indication of midcarpal fusion is SNAC or SLAC wrist grade 3. The main complication of circular plate (most common technique) is non-union. In this context, the purpose of our work was to propose the use of break-away compression screws to decrease the rate of non-union. Our series included ten patients. The fusion was fixed using two break-away compression screws (2mm diameter). No bone graft was used. As assessment, subjective (pain, Quick-DASH) and objective (strength, mobility) criteria were reviewed at follow-up. All the criteria were significantly improved after operation except mobility. Among the complications, we noticed one delayed bone-healing with a good outcome and a radiological consolidation. Midcarpal fusion by dorsal approach using break-away compression screws appears to us a technique of interest, not requiring a bone graft, with good cost effectiveness.

Strong quantum memory at resonant Fermi edges revealed by shot noise.

Studies of non-equilibrium current fluctuations enable assessing correlations involved in quantum transport through nanoscale conductors. They provide additional information to the mean current on charge statistics and the presence of coherence, dissipation, disorder, or entanglement. Shot noise, being a temporal integral of the current autocorrelation function, reveals dynamical information. In particular, it detects presence of non-Markovian dynamics, i.e., memory, within open systems, which has been subject of many current theoretical studies. We report on low-temperature shot noise measurements of electronic transport through InAs quantum dots in the Fermi-edge singularity regime and show that it exhibits strong memory effects caused by quantum correlations between the dot and fermionic reservoirs. Our work, apart from addressing noise in archetypical strongly correlated system of prime interest, discloses generic quantum dynamical mechanism occurring at interacting resonant Fermi edges.

Enhanced shot noise in tunneling through a stack of coupled quantum dots.

We have investigated the noise properties of the tunneling current through vertically coupled self-assembled InAs quantum dots. We observe super-Poissonian shot noise at low temperatures. For increased temperature this effect is suppressed. The super-Poissonian noise is explained by capacitive coupling between different stacks of quantum dots.

A bit of sex stabilizes host-parasite dynamics.

To date, only a few studies have focused on the effects of sex on population dynamics. Previous models have typically found that sexual reproduction dampens population fluctuations. Although asexual and sexual reproduction are just the two endpoints along a continuum of varying rates of sex, previous work has ignored the effects of intermediate degrees of sex on population dynamics. Here we study the effects of partial sexual reproduction (i.e. sex occurs only every few generations or with small probability in each generation) on the coupled population dynamics of a Nicholson-Bailey host-parasite model. We show that complex dynamics are simplified for high host population growth rates if the frequency of sex is sufficiently high in both host and parasite: sex decreases fluctuations in population density, and leads to non-chaotic dynamics for population growth rates that would result in chaotic dynamics in the absence of sexual reproduction. However, the simplification does not increase gradually with an increasing frequency of sex but appears abruptly at low-to-intermediate frequencies of sex. For some parameter settings, intermediate frequencies of sexual reproduction can simplify the dynamics more than lower or higher frequencies. Thus, in agreement with earlier results, sexual reproduction typically stabilizes complex population dynamics in our models. Additionally, our results suggest that low-to-intermediate frequencies of sex may often be as (or even more) stabilizing as high frequencies.