STUDY CORRELATING NIOBIUM SURFACE ROUGHNESS WITH SURFACE PARTICLE COUNTS

Abstract A study has been initiated at Michigan State University (MSU) to relate the surface preparation of Superconducting Radio Frequency (SRF) resonators and surface particle counts, using niobium samples. During fabrication, undesired surface roughness can develop on the internal surfaces of the resonators. The final cavity finish will be product of material forming, machining, welding, chemistry, high-pressure rinsing, and handling of the niobium material. This study will document niobium samples treated with MSU standard processing procedures; first measuring the surface roughness, then polishing samples with defined techniques, processing, and measuring surface particle counts. The samples will include as received niobium, machined surfaces, welded surfaces, and surfaces with characterized surface imperfections (scratches)

Superconducting Resonators Development for the FRIB and ReA Linacs at MSU: Recent Achievements and Future Goals

The superconducting driver and post-accelerator linacs of the FRIB project, the large scale radioactive beam facility under construction at MSU, require the construction of about 400 low-{beta} Quarter-wave (QWR) and Half-wave resonators (HWR) with four different optimum velocities. 1st and 2nd generation prototypes of {beta}{sub 0} = 0.041 and 0.085 QWRs and {beta}{sub 0} = 0.53 HWRs have been built and tested, and have more than fulfilled the FRIB and ReA design goals. The present cavity surface preparation at MSU allowed production of low-{beta} cavities nearly free from field emission. The first two cryostats of {beta}{sub 0} = 0.041 QWRs are now in operation in the ReA3 linac. A 3rd generation design of the FRIB resonators allowed to further improve the cavity parameters, reducing the peak magnetic field in operation and increasing the possible operation gradient, with consequent reduction of the number of required resonators. The construction of the cavities for FRIB, which includes three phases for each cavity type (development, pre-production and production runs) has started. Cavity design, construction, treatment and performance will be described and discussed

Millisecond-Timescale Local Network Coding in the Rat Primary Somatosensory Cortex

Correlation among neocortical neurons is thought to play an indispensable role in mediating sensory processing of external stimuli. The role of temporal precision in this correlation has been hypothesized to enhance information flow along sensory pathways. Its role in mediating the integration of information at the output of these pathways, however, remains poorly understood. Here, we examined spike timing correlation between simultaneously recorded layer V neurons within and across columns of the primary somatosensory cortex of anesthetized rats during unilateral whisker stimulation. We used Bayesian statistics and information theory to quantify the causal influence between the recorded cells with millisecond precision. For each stimulated whisker, we inferred stable, whisker-specific, dynamic Bayesian networks over many repeated trials, with network similarity of 83.3±6% within whisker, compared to only 50.3±18% across whiskers. These networks further provided information about whisker identity that was approximately 6 times higher than what was provided by the latency to first spike and 13 times higher than what was provided by the spike count of individual neurons examined separately. Furthermore, prediction of individual neurons' precise firing conditioned on knowledge of putative pre-synaptic cell firing was 3 times higher than predictions conditioned on stimulus onset alone. Taken together, these results suggest the presence of a temporally precise network coding mechanism that integrates information across neighboring columns within layer V about vibrissa position and whisking kinetics to mediate whisker movement by motor areas innervated by layer V

Using brain–computer interfaces to induce neural plasticity and restore function

Analyzing neural signals and providing feedback in real-time is one of the core characteristics of a brain-computer interface (BCI). As this feature may be employed to induce neural plasticity, utilizing BCI-technology for therapeutic purposes is increasingly gaining popularity in the BCI-community. In this review, we discuss the state-of-the-art of research on this topic, address the principles of and challenges in inducing neural plasticity by means of a BCI, and delineate the problems of study design and outcome evaluation arising in this context. The review concludes with a list of open questions and recommendations for future research in this field

الوضع الجيولوجي لصخور الأساس في سانت كاترين سيناء - مصر

St. Catherine area, some 900 km in size, is dominated by basement rocks Encompassing old continental gneisses, metasediments, greenstone belt, calc-alkaline granites (G-II-granites), rift-related volcanics (RV), and anorogenic within plate granites (G-III-granites). The greenstone belt is composed of subduction-related volcanics (SV) intercalated with metasediments. These volcanics split into older group (moderately metamorphosed) and younger group (slightly metamorphosed). The calc-alkaline granites were formed during collision and partial melting of the lower crust. Probably mantle materials were incorporated in the melt. The rift-related volcanics (RV), and the anorogenic granites form, in the central part of St. Catherine, an incomplete ring massif intruded by a granitic belt of younger age. The igneous activity and the structural development are related in space and time. The first event was the formation of the southern part of the ring fault along which alkalibasalts were erupted (rift-related old volcanics). This phase was followed by the eruption of alkalirhyolites and ignimbrites (rift-related young volcanics). Wide assimilation processes occurred where the alkalibasalts are converted into a black syenitoid rock. This later volcanic phase was the surface expression of an alkaline syenite-granite magmatism. The earlier member of these alkaline plutonites was alkalie-red syenite emplaced along the progressively formed northern part, of the ring fault. Crustal melting then increased and acidic members of red-granite, leuco-granite, and granophyric granite were successively emplaced, crossing the ring massif. These alkaline granitoids are anorogenic plutonites formed during hot spot and incipient rifting mechanism.تغطي صخور القاعدة منطقة سانت كاترين (900 كم 2) ، وتشمل هذه الصخور الرسوبيات القارية المتحولة في نطاق الحزام الجزري والرسوبيات المتحولة القديمة والصخور البركانية ( أ س في ) ، الجرانيت الكالس قلوي (جـ 2 ) ، الصخور البركانية ( ارفي ) والجرانيت (جـ 3) . وتكون الصخور البركانية (ارفي ) والجرانيت (جـ 3) معقد حلقي بيضاوي الشكل غير كامل . ولقد تكونت الصخور البركانية (ا س في ) ، الجرانيت (ب 2) في بيئات جزر قوسية بينما تكون الجرانيت (جـ 3) والصخور البركانية (ارفي ) خلال الألواح . ولقد تكون معقد سانت كاترين الحلقي لطفح البازلت القلوي خلال صدع دائري ثم تلا ذلك طفح الرايوليت القلوي حيث تمت عملية تمثيل بينهما كونت صخور مماثلة للسيانيت في الجزء الجنوبي اما الجزء الشمالي فيتكون من السيانيت الأحمر الذي قطع بالجوانيت (جـ3) فيما بعد

جيوكيمياء صخور القاع بمنطقة سانت كاترين سيناء - مصر

St. Catherine area, dominated by basement rocks encompass old continental gneisses, metasediments, greenstone belt, calc-alkaline granites (G-II-granites), rift-related volcanies (RV), and anorogenic within plate granites (G-III-granites). Comparative geoehemieal study has been carried out between the G-II-, and the G-III-granites and between the SV-, and RV-volcanics. The geoehemieal criteria strongly confirm island arc environment for the SV, and suture related environment for the G-II-granites. The most reasonable setting for the RV-volcanics and the G-III-granites is the anorogenic or within plate environment.تتكون منطقة سانت كاترين من صخور نيس قاسي من النوع القديم ورسوبيات متحوله وبنية صخرية خضراء وجرانيت كلسي قلوي وبركانيات تكونت نتيجة للخسف وجرانيت قلوي قاسي لاتكتوني . وقد تم تحليل 39 عينة من القاعيات والبركانيات لمعرفة محتوى العناصر الأساسية والشحيحة فيها وبحساب مقاييس جيوكيميائية عديدة وتوقيع النتائج على منحنيات عالمية ومقترحة تبين وجود علاقة جيوكيميائية بين القاعيات والبركانيات . وقد دلت الدراسة على أن البركانيات اللي تكونت في نطاق اندساس قد قذفت في أقواس جذرية بركانية أما الجرانيت الكلسي القلوي فقد تداخل في نطاق حرفي . وقد أثبتت الدراسة أيضاً أن أنسب الأوضاع التكتونية لتكون بركانيات الخسف والجرانيت القلوي القاري هو البيئة التكتونية التي تسود داخل الألواح