Critical velocity for the vortex core reversal in perpendicular bias magnetic field

For a circular magnetic nanodot in a vortex ground state we study how the critical velocity $v_c$ of the vortex core reversal depends on the magnitude $H$ of a bias magnetic field applied perpendicularly to the dot plane. We find that, similarly to the case $H$ = 0, the critical velocity does not depend on the size of the dot. The critical velocity is dramatically reduced when the negative (i.e. opposite to the vortex core direction) bias field approaches the value, at which a \emph{static} core reversal takes place. A simple analytical model shows good agreement with our numerical result.Comment: 4 pages, 2 figure

Current algorithm for the surgical treatment of facial pain

<p/> <p>Background</p> <p>Facial pain may be divided into several distinct categories, each requiring a specific treatment approach. In some cases, however, such categorization is difficult and treatment is ineffective. We reviewed our extensive clinical experience and designed an algorithmic approach to the treatment of medically intractable facial pain that can be treated through surgical intervention.</p> <p>Methods</p> <p>Our treatment algorithm is based on taking into account underlying pathological processes, the anatomical distribution of pain, pain characteristics, the patient's age and medical condition, associated medical problems, the history of previous surgical interventions, and, in some cases, the results of psychological evaluation. The treatment modalities involved in this algorithm include diagnostic blocks, peripheral denervation procedures, craniotomy for microvascular decompression of cranial nerves, percutaneous rhizotomies using radiofrequency ablation, glycerol injection, balloon compression, peripheral nerve stimulation procedures, stereotactic radiosurgery, percutaneous trigeminal tractotomy, and motor cortex stimulation. We recommend that some patients not receive surgery at all, but rather be referred for other medical or psychological treatment.</p> <p>Results</p> <p>Our algorithmic approach was used in more than 100 consecutive patients with medically intractable facial pain. Clinical evaluations and diagnostic workups were followed in each case by the systematic choice of the appropriate intervention. The algorithm has proved easy to follow, and the recommendations include the identification of the optimal surgery for each patient with other options reserved for failures or recurrences. Our overall success rate in eliminating facial pain presently reaches 96%, which is higher than that observed in most clinical series reported to date</p> <p>Conclusion</p> <p>This treatment algorithm for the intractable facial pain appears to be effective for patients with a wide variety of painful conditions and may be recommended for use in other institutions.</p

Subcallosal cingulate deep brain stimulation for treatment-resistant depression: a multi-site, randomized, sham-controlled trial

Background: Deep brain stimulation (DBS) of the subcallosal cingulate white matter (SCC) has shown promise as an intervention for patients with chronic, unremitting depression (TRD). To test the safety and efficacy of DBS for TRD, a prospective, randomized, sham-controlled trial was conducted. Methods: Participants with TRD were implanted with a DBS system targeting bilateral SCC white matter and randomized to six months of active versus sham DBS followed by six months open-label SCC DBS. The primary outcome was response rate at the end of the six-month double-blind phase. Response was defined as a 40% or greater reduction in depression severity from baseline. A futility analysis was performed when approximately half of the proposed sample received DBS implantation and completed the double-blind phase. At the conclusion of the 12-month study, a subset of patients continued to be followed for up to 24 months. Findings: Prior to the futility analysis, 90 participants were randomized to active (N=60) versus sham (N=30) stimulation. Both groups showed improvement, but there was no statistically significant difference in response rate during the double-blind, sham-controlled phase. Participants continued to improve during the six months open-label phase. Long-term response and remission rates for all participants receiving active DBS open-label were, respectively, 40% and 19% at 12 months, 51% and 17% at 18 months, and 48% and 25% at 24 months. Twenty-eight patients experienced 39 adverse events; eight of these (in seven patients) were deemed to be related to the study device and/or surgery. Interpretation: This study confirmed the safety and feasibility of SCC DBS as a treatment for TRD but failed to show statistically significant antidepressant efficacy in a six months double-blind, sham-controlled trial. Long-term (up to 24 months) open-label SCC DBS was associated with a response rate of nearly 50%, with 25% of participants remitted. These rates are clinically meaningful and higher than those expected in this patient population with treatment-as-usual

Stability of Yellow Fever Virus under Recombinatory Pressure as Compared with Chikungunya Virus

Recombination is a mechanism whereby positive sense single stranded RNA viruses exchange segments of genetic information. Recent phylogenetic analyses of naturally occurring recombinant flaviviruses have raised concerns regarding the potential for the emergence of virulent recombinants either post-vaccination or following co-infection with two distinct wild-type viruses. To characterize the conditions and sequences that favor RNA arthropod-borne virus recombination we constructed yellow fever virus (YFV) 17D recombinant crosses containing complementary deletions in the envelope protein coding sequence. These constructs were designed to strongly favor recombination, and the detection conditions were optimized to achieve high sensitivity recovery of putative recombinants. Full length recombinant YFV 17D virus was never detected under any of the experimental conditions examined, despite achieving estimated YFV replicon co-infection levels of ∼2.4×106 in BHK-21 (vertebrate) cells and ∼1.05×105 in C710 (arthropod) cells. Additionally YFV 17D superinfection resistance was observed in vertebrate and arthropod cells harboring a primary infection with wild-type YFV Asibi strain. Furthermore recombination potential was also evaluated using similarly designed chikungunya virus (CHIKV) replicons towards validation of this strategy for recombination detection. Non-homologus recombination was observed for CHIKV within the structural gene coding sequence resulting in an in-frame duplication of capsid and E3 gene. Based on these data, it is concluded that even in the unlikely event of a high level acute co-infection of two distinct YFV genomes in an arthropod or vertebrate host, the generation of viable flavivirus recombinants is extremely unlikely

An Update on Surgical Treatment of Parkinson Disease

Over the last several decades, surgery became an integral part of comprehensive treatment of advanced Parkinson disease (PD).  Better understanding of disease mechanisms and advancement of technological innovations resulted in universal acceptance of deep brain stimulation (DBS) as an important part of the PD treatment algorithm. Based on experience with thousands of operated patients, the criteria for patient selection, preoperative evaluation, procedural details, and nuances of post-operative management are now well established. As a matter of fact, surgery in general and DBS in particular are now included in every guideline of PD management making it an option to consider when disease progresses and medical side effects occur.</jats:p