Нелінійність дифузійних резисторів при струмі високої щільності

У роботі представлено результати експериментального дослідження залежності опору дифузійних резисторів (ДР) від струму, виготовлених за технологією "кремній з діелектричною ізоляцією", з різними геометричними характеристиками, зокрема, довжиною та товщиною, при густині струму до 105 A/см2. Проведено аналіз отриманих результатів і визначено три області на кривих залежності опору резистора від струму R(I). Перша область – омічна ділянка, на якій значення опору дифузійного резистора лінійно залежить від струму. Друга область кривої R(I) характеризується наявністю сильної нелінійності та стрибками і різким збільшенням опору ДР, що пов'язано із виникненням області високого електричного поля в ДР. Третя область залежності R(I) характеризується зменшенням величини опору від струму. Чим товщим є ДР, тим менше пікове значення опору. Показано, що зміна довжини і зменшення товщини дифузійних резисторів призводять до зміни протяжності лінійної ділянки залежності R(I). Чим менша довжина, тим менший опір зразка і тим довша ділянка сталого диференційного опору. Із залежності диференціального опору від струму визначено області лінійності опору дифузійного резистора. Область лінійності опору була визначена як область, де зміна диференціального опору не перевищувала 10 % від його значення при малому електричному полі: найбільша область лінійності резистора має місце в зразку довжиною 2.4 мкм та товщиною 8.4 мкм. Виявлені особливості поведінки опору дифузійного резистора пояснюються зміною його фізичних характеристик в результаті значного самонагрівання.The paper presents the results of an experimental study of the current dependence of the resistance of diffusion resistors (DR) produced by the "silicon with dielectric insulation" technology, with different geometric characteristics, in particular, length and thickness, with a current density of 105 A/cm2. The analysis of the obtained results is carried out and three areas on the dependence of resistance on current R(I) are determined. The first region is an ohmic plot, on which the resistance value of the diffusion resistor is linearly dependent on the current value. The second region of the curve R(I) is characterized by the presence of strong nonlinearity, jumps and a sharp increase in the resistance of the DR, which happen due to the emergence of a high electric field in the DR. The third region on R(I) is characterized by a decrease in the value of the current resistance: the thicker the DR, the lower the peak value of the resistance. It is shown that the change in the length and the decrease in the thickness of the diffusion resistors lead to a change in the length of the linear region on R(I): the smaller the length, the lower the resistance of the sample and the longer the area of stable differential resistance. The region of the linearity of the diffusion resistor is determined on the basis of the differential resistance on the current dependence. The linearity of the resistance was defined as the region where the change in the differential resistance did not exceed 10 % of its value at some small electric field: the largest region of the linearity of the resistor is present in a specimen with a length of 2.4 μm and a thickness of 8.4 μm. The revealed characteristics of the behavior of the resistance of the diffusion resistor are due to the change in its physical characteristics as a result of significant self-heating

Endovascular treatment of the patient with vascular type of Ehlers–Danlos syndrome with bilateral dissection stenoses and aneurysms in V3- andV4- segments of vertebral arteries

A case of treatment of a patient with type 4 of Ehlers–Danlos syndrome and bilateral dissection stenoses and aneurysms in V3and V4-segments of vertebral arteries is described. Also another vascular anomaly was verified: the aberrant right subclavian artery (arteria lusoria). Сerebral angiography with dynamic rotation of the neck revealed a bow hunter's syndrom, which consists in the restriction of blood flow in the right vertebral artery when the head is turned to the left. Stage-by-stage endovascular reconstruction of both vertebral arteries was performed. Firstly, LVIS stent was implanted in the left vertebral artery on the level of the dissection lesion. Then, the aneurysm of the left vertebral artery was embolized by detachable coils. Balloon angioplasty was performed in the stented segment with the compliance balloon-catheter Scepter. On the series of angiograms: the aneurysm is totally excluded, the stenosis of the artery is eliminated. After 1 month, the second stage of endovascular treatment in the same volume in the right vertebral artery was performed. At attempts of a hemostasis with the vascular closure device Аngioseal were unsuccessful in both operations. Hemostasis was successfully performed by manual compression of the puncture site. A mutation in the gene COL3A1, responsible for the synthesis of procollagen III type, was confirmed by Ehlers–Danlos syndrome of type 4 (vascular type) at the subsequent genotyping of the patient. The patient's neurological symptoms regressed to a great extent. Endovascular methods can be effective in the treatment of vertebral arteries dissection lesions in patients with vascular type of Ehlers–Danlos syndrome

Endovascular treatment of a patient with traumatic dissection lesions of both vertebral arteries obtained during chiropractic manipulation

The observation of endovascular treatment of a 34-year-old woman with bilateral dissection lesions of vertebral arteries in V4-segments with occlusion of the right vertebral artery and right posterior inferior cerebellar artery, severe stenosis of the left vertebral artery caused by chiropractic manipulation in the neck region is described. There are intensive staticolocomotor and dynamic coordinating insufficiency, severe neck pain, headache, severe dizziness, Wallenberg syndrome, moderate central tetraparesis. MRI of the brain on the DWI Isotropic identified the hyperintensive round-shaped foci in the right hemisphere of the cerebellum, in the right side of cerebellum worm, in the right side of the medulla oblongata and in the right side of the pons (DWI BSS 3). Selective cerebral angiography was performed an hour after the clinic manifestation. Simultaneously, balloon angioplasty of severe dissection stenosis was performed in the V4-segment of the left vertebral artery by the compliant balloon-catheter Scepter C. In 18 hours from the development of vertebral artery dissection, self-expending stent LVIS was implanted into the left vertebral artery in the zone of dissection lesion. On the control angiograms: the left vertebral artery patency is restored without stenosis all along. The stent is fully opened. A second contrast contour is determined outside the stent in the dissection zone. All the arteries of the vertebrobasilar basin above the vertebrobasilar junction are passable. The V4-segment of the right vertebral artery is contrasted through the vertebrobilar junction. There was a rapid regression of neurological symptoms in the postoperative period. Only mild hypoesthesia on the right side in the outer Sölder’s zone, light coordination disorders on the right were remained. Control selective cerebral angiography revealed recanalization of the right vertebral artery and the right posterior cerebellar artery. But distal basin of the right posterior cerebellar artery is very poorly. The left vertebral artery is passable all over, but in the place of the former dissection, two equivalent arterial «sleeves» were formed according to the fenestration type. One «sleeve» is formed by a stent, the other — outside. All arteries of the vertebrobasilar basin are contrasted. The mild hemihepesthesia on the right side of the face in the outer Sölder’s zone, light coordination disorders on the right are remained. Implantation of the self-expanding stent LVIS allowed to restore the dominant vertebral artery and restrict ischemic brain damage in the brain stem and cerebellum in a patient with a both vertebral arteries dissection lesion caused by chiropractic neck manipulations

PEAT-CLSM: A Specific Treatment of Peatland Hydrology in the NASA Catchment Land Surface Model

Peatlands are poorly represented in global Earth system modeling frameworks. Here we add a peatland-specific land surface hydrology module (PEAT-CLSM) to the Catchment Land Surface Model (CLSM) of the NASA Goddard Earth Observing System (GEOS) framework. The amended TOPMODEL approach of the original CLSM that uses topography characteristics to model catchment processes is discarded, and a peatland-specific model concept is realized in its place. To facilitate its utilization in operational GEOS efforts, PEAT-CLSM uses the basic structure of CLSM and the same global input data. Parameters used in PEAT-CLSM are based on literature data. A suite of CLSM and PEAT-CLSM simulations for peatland areas between 40°N and 75°N is presented and evaluated against a newly compiled data set of groundwater table depth and eddy covariance observations of latent and sensible heat fluxes in natural and seminatural peatlands. CLSM's simulated groundwater tables are too deep and variable, whereas PEAT-CLSM simulates a mean groundwater table depth of −0.20 m (snow-free unfrozen period) with moderate temporal fluctuations (standard deviation of 0.10 m), in significantly better agreement with in situ observations. Relative to an operational CLSM version that simply includes peat as a soil class, the temporal correlation coefficient is increased on average by 0.16 and reaches 0.64 for bogs and 0.66 for fens when driven with global atmospheric forcing data. In PEAT-CLSM, runoff is increased on average by 38% and evapotranspiration is reduced by 19%. The evapotranspiration reduction constitutes a significant improvement relative to eddy covariance measurements