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This paper explores the use of dual-mode scramjet shock train control taking an adaptive control approach known as characteristic model-based all-coefficient adaptive control. In this study a simple, semiempirical model of a dual-mode scramjet is developed. This model is suited to computationally efficient control simulation for the assessment of different control approaches. All-coefficient adaptive control is predicted to be as capable of controlling the shock train location, and rejecting disturbances, as a traditional proportional–integral–derivative controller. However, prior knowledge of the scramjet plant is not required for the all-coefficient adaptive control, and it is predicted that this controller is able to better perform when changes in the plant take place. When characteristics of the plant deviate from their nominal values, the adaptive controller can adjust in real time and maintain a stable system response. This is the first time the performance of all-coefficient adaptive control has been examined in the open literature for a dual-mode scramjet. It is also the first time all-coefficient adaptive control of a dual-mode scramjet has been compared to proportional–integral–derivative control. The simple, empirically based plant model of the dual-mode scramjet is also new, and it is well suited to real-time and hardware-in-the-loop control simulations.

Accurate estimation of the bleed orifice flow coefficient, which relates bleed plenum pressure to mass flow removed, is important to predicting inlet performance, as well as, estimating bleed drag. Much of the flow coefficient data at conditions of interest to inlet designers is based on bleed plates with multiple rows of holes. The flow coefficient for these plates is typically presented as a function of bleed plenum pressure normalized by the freestream total pressure. Numerical simulations of the flowfield at the entrance of the bleed hole show that the flow is complex, especially for supersonic free stream flow, whereby an alternating expansion/compression wave pattern initiates at the porous bleed surface as the flow turns to enter the hole. This implies that a significant portion of the tangential flow total pressure is given up upon entering a 90° hole. For large aspect ratio (length-to-diameter ratio) bleed holes the effect of the frictional pressure drop is to lower the required plenum pressure to achieve a given mass flow. Conversely, the mass flow will be reduced due to the higher pressure at the start of the duct. Empirical data show that the flow coefficient for supersonic boundary layer bleed holes stops increasing as the plenum pressure to total pressure ratio continues to decrease, indicating that the flow becomes choked. Thus the chocked flow condition helps to make the bleed hole mass flow under these conditions less sensitive or insensitive to the effects of friction caused by the extended hole length. The extent to which this happens is the focus of the current effort, with the paper reporting on experimental and numerical results on flow characteristics and mass flow performance of supersonic bleed holes featuring a range of aspect ratios beyond what has been reported in the past.

Deep brain stimulation (DBS) is a widely used neurosurgical approach to treating tremor and other movement disorders1,2,3. In addition, the use of DBS in a number of psychiatric diseases, including obsessive-compulsive disorders and depression, is currently being tested4,5,6. Despite the rapid increase in the number of individuals with surgically implanted stimulation electrodes, the cellular pathways involved in mediating the effects of DBS remain unknown1. Here we show that DBS is associated with a marked increase in the release of ATP, resulting in accumulation of its catabolic product, adenosine. Adenosine A1 receptor activation depresses excitatory transmission in the thalamus and reduces both tremor- and DBS-induced side effects. Intrathalamic infusion of A1 receptor agonists directly reduces tremor, whereas adenosine A1 receptor–null mice show involuntary movements and seizure at stimulation intensities below the therapeutic level. Furthermore, our data indicate that endogenous adenosine mechanisms are active in tremor, thus supporting the clinical notion that caffeine, a nonselective adenosine receptor antagonist, can trigger or exacerbate essential tremor7. Our findings suggest that nonsynaptic mechanisms involving the activation of A1 receptors suppress tremor activity and limit stimulation-induced side effects, thereby providing a new pharmacological target to replace or improve the efficacy of DBS.

The Department of Neurosurgery at the University of Rochester has a long legacy of excellent patient care and innovation in the neurosciences. The department's founder, Dr. William Van Wagenen, was a direct pupil of Harvey Cushing and the first president of the Harvey Cushing Society. His successor, Dr. Frank P. Smith, was also a leader in organized neurosurgery and helped to permanently memorialize his mentor with an endowed fellowship that today is one of the most prestigious training awards in neurosurgery. The first 2 chiefs are honored every year by the department with memorial invited lectureships in their names. The department is home to a thriving multidisciplinary research program that fulfills the lifelong vision of its founder, Dr. Van Wagenen.

Detonations can be used to generate a high-pressure gas of high acoustic speed to drive a shock tube. Recently, detonation driven facilities have been implemented for meaningful hypervelocity testing. These facilities can be operated with the detonation wave propagating either downstream or upstream. The advantages and problems associated with these methods are discussed. In addition to a performance comparison between these two modes, comparisons with other high-performance techniques, such as free piston and gun tunnels, are also made. At present, detonation driven facilities are generally of lower performance than free piston tunnels. However, they appear easier to operate and have a lower capital investment.

The note describes the theoretical basis of chemical recombination in an expansion tube which simulates energy, Reynolds number, and stream chemistry at near-orbital velocities. Expansion tubes can satisfy ground-based hypersonic propulsion and aerothermal testing requirements.

The authors report the case of a 74-year-old woman who underwent an L-2 vertebral kyphoplasty. The patient experienced delayed postoperative hemodynamic deterioration that may have been caused by embolization of polymethylmethacrylate (PMMA) cement through the right cardiac ventricular wall. Cardiac and pulmonary embolization of bone cement can develop as a complication of vertebral kyphoplasty. Surgeons should be alert to this potentially life-threatening condition when performing this increasingly popular form of spine procedure.

This paper shows the possibility of applying concept maps as diagnostic tools in assessing knowledge. The authors introduce the terms “ideal knowledge structure”, “desired knowledge structure” and “real knowledge structure” as milestones in indicating levels of acquired knowledge. The role of concept mapping in the diagnostics of knowledge was tested in the secondary-school teaching of biochemistry. The pedagogical experiment was performed with secondary-school students form Novi Sad (Serbia). Students were tested in two biochemical topics (nucleic acids and protein synthesis) and concept maps were created for the results of each student after final and retention tests. A comparison of the desired knowledge structure and the real knowledge structure revealed the possible application of concept maps: in establishing the level of acquired knowledge; in illustrating students’ efforts and ability to learn biochemical content; and as indicators of the level of the retention of knowledge and of the efficiency of the applied teaching method. Through concept maps, teachers can evaluate their own performance and gain important feedback on their own work., U ovom radu prikazana je mogućnost primjene konceptnih mapa kao dijagnostičkog sredstva u procjeni učeničkog znanja. Autori uvode nove termine: „idealna struktura znanja”, „poželjna struktura znanja” i „realna struktura znanja” kao pokazatelje nivoa usvojenosti znanja. Uloga konceptnih mapa kao dijagnostičkog sredstva testirana je u oblasti gimnazijske nastave biokemije. U pedagoškom eksperimentu sudjelovali su gimnazijalci iz Novog Sada (Srbija). Ispitivano je njihovo poznavanje nastavnih sadržaja iz dvije nastavne teme (nukleinske kiseline i biosinteza proteina). Kreirane su konceptne mape realne strukture znanja za svakog učenika nakon fi nalnog testa i testa retencije znanja. Usporedbom mapa poželjne i realnih struktura znanja ustanovljene su moguće primjene konceptnih mapa: u određivanju nivoa usvojenosti znanja; u ocjeni uloženog truda i sposobnosti učenika da usvoji biokemijske sadržaje; kao indikatora nivoa retencije znanja; kao mjere efi kasnosti primijenjene nastavne metode. Radom s konceptnim mapama nastavnici mogu ocijeniti svoje rezultate i steći uvid u vlastiti rad.

NASA s HYPULSE facility at GASL has been reconfigured to permit free jet testing of the Hyper-X flowpath at flight Mach numbers of 7 and 10. Among the required changes are addition of a converging-diverging nozzle to permit operation in a reflected shock tunnel mode, a 7 ft. diameter test cabin and a 30 in. diameter contoured nozzle. However, none of these changes were allowed to interfere with rapid recovery of the prior shock-expansion tunnel mode of operation, and indeed certain changes should enhance facility usefulness and productivity in either mode. A previously-developed shock-induced detonation mode of driving the facility has been successfully applied to both reflected shock tunnel operation at Mach 10 flight conditions, with tailored interface operation, and shock-expansion tunnel operation at flight conditions corresponding to Mach numbers from 12 to 25. Tailored interface operation at Mach 7 has been achieved with an unheated helium driver. In the present paper, the rationale for a dual mode shock expansion/reflected shock tunnel is discussed, and the capabilities and limitations for each mode are outlined. The physical changes in the HYPULSE facility to achieve dual mode capability are also described. Limited calibration data obtained to date in the new reflected shock tunnel mode are presented and the anticipated flight simulation map with dual mode operation is also outlined.

Utilization of an expansion tube to acquire turbulent, compressible free shear layer data with gases of direct relevance to hypersonic combustion systems (nitrogen, hydrogen, and oxygen) is demonstrated. Visualizations of the free shear layer by laser holographic interferometry and schlieren imaging show a distinctly asymmetric growth rate that is highly preferential toward the lower speed (secondary stream) side. For the nitrogen/nitrogen case, for which the convective velocity was lowest and convective Mach number highest, the growth rate on the primary side was virtually zero until the mixing layer reached the opposite (secondary) wall.

SURGICAL MANAGEMENT OF MOVEMENT DISORDERS edited by Gordon Baltuch and Matthew Stern , 328 pp., Informa Healthcare, $199.95 (hardback), $99.95 (paperback) I’ve always agreed with the maxim stating that “good things often come in small packages.” This is particularly apt for Gordon Baltuch’s and Matthew Stern’s Surgical Management of Movement Disorders : appealing for its compactness, not only in size, but, more importantly, for its careful condensation of a large body of complex information. The book is divided into seven sections. Section I concerns Parkinson disease and comprises five chapters devoted to various aspects of this disease. The last chapter entitled “Novel Surgical Strategies” is particularly well written, …