Preferential Deposition of Snow and Dust Over Hills: Governing Processes and Relevant Scales

Preferential deposition of snow and dust over complex terrain is responsible for a wide range of environmental processes and accounts for a significant source of uncertainty in the surface mass balances of cold and arid regions. Despite the growing body of literature on the subject, previous studies reported contradictory results on the location and magnitude of deposition maxima and minima. This study aims at unraveling the governing processes of preferential deposition in a neutrally stable atmosphere and to reconcile seemingly inconsistent results of previous works. For this purpose, a comprehensive modeling approach is developed, based on large eddy simulations of the turbulent airflow, Lagrangian stochastic model of particle trajectories, and immersed boundary method to represent the underlying topography. The model is tested against wind tunnel measurements of dust deposition around isolated and sequential hills. A scale analysis is then performed to investigate the dependence of snowfall deposition on the particle Froude and Stokes numbers, which fully account for the governing processes of inertia, flow advection, and gravity. Model results suggest that different deposition patterns emerge from different combinations of dimensionless parameters, with deposition maxima located either on the windward or the leeward slope of the hill. Additional simulations are performed, to test whether the often used assumption of inertialess particles yields accurate deposition patterns. Results indicate that this assumption can be justified when snowflakes present dendritic shape but may generate unrealistic results for rounded particles. We finally show that our scale analysis provides qualitatively similar results for hills with different aspect ratios

Different frontal involvement in ALS and PLS revealed by Stroop event-related potentials and reaction times

BACKGROUND: A growing body of evidence suggests a link between cognitive and pathological changes in amyotrophic lateral sclerosis (ALS) and in frontotemporal lobar dementia (FTLD). Cognitive deficits have been investigated much less extensively in primary lateral sclerosis (PLS) than in ALS. OBJECTIVE: to investigate bioelectrical activity to Stroop test, assessing frontal function, in ALS, PLS and control groups. METHODS: 32 non-demented ALS patients, 10 non-demented PLS patients and 27 healthy subjects were included. Twenty-nine electroencephalography (EEG) channels with binaural reference were recorded during covert Stroop task performance, involving mental discrimination of the stimuli and not vocal or motor response. Group effects on event related potentials (ERPs) latency were analyzed using statistical multivariate analysis. Topographic analysis was performed using low resolution brain electromagnetic tomography (LORETA). RESULTS: ALS patients committed more errors in the execution of the task but they were not slower, whereas PLS patients did not show reduced accuracy, despite a slowing of reaction times (RTs). The main ERP components were delayed in ALS, but not in PLS, compared with controls. Moreover, RTs speed but not ERP latency correlated with clinical scores. ALS had decreased frontotemporal activity in the P2, P3 and N4 time windows compared to controls. CONCLUSION: These findings suggest a different pattern of psychophysiological involvement in ALS compared with PLS. The former is increasingly recognized to be a multisystems disorder, with a spectrum of executive and behavioural impairments reflecting frontotemporal dysfunction. The latter seems to mainly involve the motor system, with largely spared cognitive functions. Moreover, our results suggest that the covert version of the Stroop task used in the present study, may be useful to assess cognitive state in the very advanced stage of the disease, when other cognitive tasks are not applicable

Acute myelopathy selectively involving lumbar anterior horns following intranasal insufflation of ecstasy and heroin

We report a patient who developed acute myelopathy after intranasal insufflation of amphetamines and heroin. The functional prognosis was very poor; after 4 months, she remained paraplegic. MRI imaging showed selective T2 hyperintensity and intense enhancement confined to the spinal anterior horns and lumbar nerve roots and plexus. This unique MRI pattern, together with neurophysiological data, suggests that the pathological process at the first primary affected spinal anterior horns (SAH), conditioning motoneuron cell death, and then nerve roots and lumbar plexus as a consequence of wallerian degeneratio

Safety and efficacy of nabiximols on spasticity symptoms in patients with motor neuron disease (CANALS): a multicentre, double-blind, randomised, placebo-controlled, phase 2 trial

Background: Spasticity is a major determinant of disability and decline in quality of life in patients with motor neuron disease. Cannabinoids have been approved for symptomatic treatment of spasticity in multiple sclerosis. We investigated whether cannabinoids might also reduce spasticity in patients with motor neuron disease. Methods: We did an investigator-initiated, randomised, double-blind, placebo-controlled, phase 2 clinical trial at four tertiary motor neuron disease centres in Italy. Eligible patients were aged 18\u201380 years; had possible, laboratory-supported probable, probable, or definite amyotrophic lateral sclerosis as defined by revised El Escorial criteria, or primary lateral sclerosis according to Pringle's criteria; had spasticity symptoms due to motor neuron disease for at least 3 months; had spasticity scores of 1 or greater in at least two muscle groups on the Modified Ashworth Scale; and were taking an antispasticity regimen that was maintained at a stable dose for 30 days before enrolment. Participants were assigned (1:1) by an independent statistician via a computer-generated randomisation sequence to a standardised oromucosal spray (nabiximols) containing a defined combination of delta-9-tetrahydrocannabinol and cannabidiol (each 100 \u3bcL actuation contained 2\ub77 mg delta-9-tetrahydrocannabinol and 2\ub75 mg cannabidiol) or to placebo for 6 weeks. Participants self-titrated during the first 14 treatment days according to a predefined escalation scheme (maximum 12 actuations per 24 h), then maintained that dose for 4 weeks. The primary endpoint was the change in the score on the Modified Ashworth Scale, which was assessed at baseline and after 6 weeks. Safety and tolerability were also monitored. Participants, investigators, site personnel, and the study statistician were masked to treatment allocation. All randomised participants who received at least one dose of study drug were included in the analysis. This trial is registered with ClinicalTrials.gov, number NCT01776970. The trial is closed to new participants with follow-up completed. Findings: Between Jan 19, 2013, and Dec 15, 2014, 60 participants were randomly assigned, and 59 participants were included in the final analysis (29 in the nabiximols group and 30 in the placebo group). Modified Ashworth Scale scores improved by a mean of 0\ub711 (SD 0\ub748) in the nabiximols group and deteriorated by a mean of 0\ub716 (0\ub747) in the placebo group (adjusted effect estimate 120\ub732 [95% CI 120\ub757 to 120\ub7069]; p=0\ub7013). Nabiximols was well tolerated, and no participants withdrew from the double-blind phase of the study. No serious adverse effects occurred. Interpretation: In this proof-of-concept trial, nabiximols had a positive effect on spasticity symptoms in patients with motor neuron disease and had an acceptable safety and tolerability profile. These findings should be investigated further in larger clinical trials. Funding: Italian Research Foundation for Amyotrophic Lateral Sclerosis