Paramagnetic Meissner effect in ZrB12 single crystal with non-monotonic vortex-vortex interactions

The magnetic response related to paramagnetic Meissner effect (PME) is studied in a high quality single crystal ZrB12 with non-monotonic vortex-vortex interactions. We observe the expulsion and penetration of magnetic flux in the form of vortex clusters with increasing temperature. A vortex phase diagram is constructed which shows that the PME can be explained by considering the interplay among the flux compression, the different temperature dependencies of the vortex-vortex and the vortex-pin interactions, and thermal fluctuations. Such a scenario is in good agreement with the results of the magnetic relaxation measurements.Comment: accepted by New Journal of Physic

Оптимизация режимов функционирования сложной агрегатированной системы механической обработки деталей

Розглянуто функціонування складної агрегатованої системи механічної обробки деталей та моделювання його у вигляді трьохрівневої системи. В якості першого рівня прийнято технічний процес механічної обробки деталей, в якості другого - процес функціонування механообробних модулів, в якості третього – функціонування системи механічної обробки деталей. Механічна обробка деталей розглянута на прикладі різання металу. Описано та обґрунтовано вибір методу циклічного покоординатного спуску, як методу оптимізації параметрів змодельованої системи механічної обробки деталей. За допомогою даного методу знайдено оптимальні значення всіх цільових функцій механообробної системи. У якості інструментарію вирішення задачі оптимізації був розроблений програмно-розрахунковий модуль для САПР процесів механічної обробки деталей.Functioning of the aggregated system of details mechanical treatment and modeling as three-level system was investigated. As a first level technical process of details mechanical treatment was adopted, as the second – functioning of the machining process modules, as the third - the operation of details mechanical treatment. Details mechanical treatment considered on the example of cutting metal. The cyclic coordinate descent method was offered and justified as method of optimizing parameters of investigated system. Using this method, optimal values of all objective functions of machining systems were found. As a tool of solving optimization problem was developed software calculation module for CAD processes of details mechanical treatment.Рассмотрено функционирование сложной агрегатированной системы механической обработки деталей и моделирование его в виде трехуровневой системы. В качестве первого уровня принято технический процесс механической обработки деталей, в качестве второго принят процесс функционирования механообрабатывающих модулей, в качестве третьего – функционирование системы механической обработки деталей. Механическая обработка деталей рассмотрена на примере резки металла. Описан и обоснован выбор метода циклического покоординатного спуска, как метода оптимизации параметров смоделированной системы механической обработки деталей. С помощью данного метода найдены оптимальные значения всех целевых функций механообрабатывающего системы. В качестве инструментария решения задачи оптимизации был разработан программно-расчетный модуль для САПР процессов механической обработки деталей

Hall effect in the vicinity of quantum critical point in Tm1-xYbxB12

The angular, temperature and magnetic field dependences of Hall resistance roH for the rare-earth dodecaboride solid solutions Tm1-xYbxB12 have been studied in a wide vicinity of the quantum critical point (QCP) xC~0.3. The measurements performed in the temperature range 1.9-300 K on high quality single crystals allowed to find out for the first time in these fcc compounds both an appearance of the second harmonic contribution in ro2H at QCP and its enhancement under the Tm to ytterbium substitution and/or with increase of external magnetic field. When the Yb concentration x increases a negative maximum of a significant amplitude was shown to appear on the temperature dependences of Hall coefficient RH(T) for the Tm1-xYbxB12 compounds. Moreover, a complicated activation type behavior of the Hall coefficient is observed at intermediate temperatures for x>0.5 with activation energies Eg~200K and Ea~55-75K in combination with the sign inversion of RH(T) at low temperatures in the coherent regime. The density of states renormalization effects are analyzed within the variation of Yb concentration and the features of the charge transport in various regimes (charge gap formation, intra-gap manybody resonance and coherent regime) are discussed in detail in Tm1-xYbxB12 solid solutions.Comment: 38 pages including 10 figures, 70 reference

Medicinal and ethnoveterinary remedies of hunters in Trinidad

BACKGROUND: Ethnomedicines are used by hunters for themselves and their hunting dogs in Trinidad. Plants are used for snakebites, scorpion stings, for injuries and mange of dogs and to facilitate hunting success. RESULTS: Plants used include Piper hispidum, Pithecelobium unguis-cati, Bauhinia excisa, Bauhinia cumanensis, Cecropia peltata, Aframomum melegueta, Aristolochia rugosa, Aristolochia trilobata, Jatropha curcas, Jatropha gossypifolia, Nicotiana tabacum, Vernonia scorpioides, Petiveria alliacea, Renealmia alpinia, Justicia secunda, Phyllanthus urinaria,Phyllanthus niruri,Momordica charantia, Xiphidium caeruleum, Ottonia ovata, Lepianthes peltata, Capsicum frutescens, Costus scaber, Dendropanax arboreus, Siparuma guianensis, Syngonium podophyllum, Monstera dubia, Solanum species, Eclipta prostrata, Spiranthes acaulis, Croton gossypifolius, Barleria lupulina, Cola nitida, Acrocomia ierensis (tentative ID). CONCLUSION: Plant use is based on odour, and plant morphological characteristics and is embedded in a complex cultural context based on indigenous Amerindian beliefs. It is suggested that the medicinal plants exerted a physiological action on the hunter or his dog. Some of the plants mentioned contain chemicals that may explain the ethnomedicinal and ethnoveterinary use. For instance some of the plants influence the immune system or are effective against internal and external parasites. Plant baths may contribute to the health and well being of the hunting dogs

Intravenous alteplase for stroke with unknown time of onset guided by advanced imaging: systematic review and meta-analysis of individual patient data

Background: Patients who have had a stroke with unknown time of onset have been previously excluded from thrombolysis. We aimed to establish whether intravenous alteplase is safe and effective in such patients when salvageable tissue has been identified with imaging biomarkers. Methods: We did a systematic review and meta-analysis of individual patient data for trials published before Sept 21, 2020. Randomised trials of intravenous alteplase versus standard of care or placebo in adults with stroke with unknown time of onset with perfusion-diffusion MRI, perfusion CT, or MRI with diffusion weighted imaging-fluid attenuated inversion recovery (DWI-FLAIR) mismatch were eligible. The primary outcome was favourable functional outcome (score of 0–1 on the modified Rankin Scale [mRS]) at 90 days indicating no disability using an unconditional mixed-effect logistic-regression model fitted to estimate the treatment effect. Secondary outcomes were mRS shift towards a better functional outcome and independent outcome (mRS 0–2) at 90 days. Safety outcomes included death, severe disability or death (mRS score 4–6), and symptomatic intracranial haemorrhage. This study is registered with PROSPERO, CRD42020166903. Findings: Of 249 identified abstracts, four trials met our eligibility criteria for inclusion: WAKE-UP, EXTEND, THAWS, and ECASS-4. The four trials provided individual patient data for 843 individuals, of whom 429 (51%) were assigned to alteplase and 414 (49%) to placebo or standard care. A favourable outcome occurred in 199 (47%) of 420 patients with alteplase and in 160 (39%) of 409 patients among controls (adjusted odds ratio [OR] 1·49 [95% CI 1·10–2·03]; p=0·011), with low heterogeneity across studies (I2=27%). Alteplase was associated with a significant shift towards better functional outcome (adjusted common OR 1·38 [95% CI 1·05–1·80]; p=0·019), and a higher odds of independent outcome (adjusted OR 1·50 [1·06–2·12]; p=0·022). In the alteplase group, 90 (21%) patients were severely disabled or died (mRS score 4–6), compared with 102 (25%) patients in the control group (adjusted OR 0·76 [0·52–1·11]; p=0·15). 27 (6%) patients died in the alteplase group and 14 (3%) patients died among controls (adjusted OR 2·06 [1·03–4·09]; p=0·040). The prevalence of symptomatic intracranial haemorrhage was higher in the alteplase group than among controls (11 [3%] vs two [<1%], adjusted OR 5·58 [1·22–25·50]; p=0·024). Interpretation: In patients who have had a stroke with unknown time of onset with a DWI-FLAIR or perfusion mismatch, intravenous alteplase resulted in better functional outcome at 90 days than placebo or standard care. A net benefit was observed for all functional outcomes despite an increased risk of symptomatic intracranial haemorrhage. Although there were more deaths with alteplase than placebo, there were fewer cases of severe disability or death. Funding: None