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This study presents a physics-based, low-order model for the trailing edge (TE) noise generated by an airfoil at low angle of attack. The approach employs incompressible resolvent analysis of the mean flow to extract relevant spanwise-coherent structures in the transitional boundary layer and near wake. These structures are integrated into Curle's solution to Lighthill's acoustic analogy to obtain the scattered acoustic field. The model has the advantage of predicting surface pressure fluctuations from first principles, avoiding reliance on empirical models, but with a free amplitude set by simulation data. The model is evaluated for the transitional flow ( Re = 5 e 4 ) around a NACA0012 airfoil at 3 deg angle of attack, which features TE noise with multiple tones. The mean flow is obtained from a compressible large eddy simulation, and spectral proper orthogonal decomposition (SPOD) is employed to extract the main hydrodynamic and acoustic features of the flow. Comparisons between resolvent and SPOD demonstrate that the physics-based model accurately captures the leading coherent structures at the main tones' frequencies, resulting in a good agreement of the reconstructed acoustic power with that of the SPOD (within 4 dB). Discrepancies are observed at high frequencies, likely linked to nonlinearities that are not considered in the resolvent analysis. The model's directivity aligns well with the data at low Helmholtz numbers, but it fails at high frequencies where the back-scattered pressure plays a significant role in directivity. This modeling approach opens the way for efficient optimization of airfoil shapes in combination with low-fidelity mean flow solvers to reduce TE noise. [ABSTRACT FROM AUTHOR]

Motivated by the influence of deformation-induced microcracks on the effective electrical properties at the macroscale, an electro-mechanically coupled computational multiscale formulation for electrical conductors is proposed. The formulation accounts for finite deformation processes and is a direct extension of the fundamental theoretical developments presented by Kaiser and Menzel (Arch Appl Mech 91:1509–1526, 2021) who assume a geometrically linearised setting. More specifically speaking, averaging theorems for the electric field quantities are proposed and boundary conditions that a priori fulfil the extended Hill–Mandel condition of the electro-mechanically coupled problem are discussed. A study of representative boundary value problems in two- and three-dimensional settings eventually shows the applicability of the proposed formulation and reveals the severe influence of microscale deformation processes on the effective electrical properties at the macroscale. [ABSTRACT FROM AUTHOR]

Motivated by advances in flexible electronic technologies and by the endeavour to develop non-destructive testing methods, this article analyses the capability of computational multiscale formulations to predict the influence of microscale cracks on effective macroscopic electrical and mechanical material properties. To this end, thin metal films under mechanical load are experimentally analysed by using in-situ confocal laser scanning microscopy (CLSM) and in-situ four point probe resistance measurements. Image processing techniques are then used to generate representative volume elements from the laser intensity images. These discrete representations of the crack pattern at the microscale serve as the basis for the calculation of effective macroscopic electrical conductivity and mechanical stiffness tensors by means of computational homogenisation approaches. A comparison of simulation results with experimental electrical resistance measurements and a detailed study of fundamental numerical properties demonstrates the applicability of the proposed approach. In particular, the (numerical) errors that are induced by the representative volume element size and by the finite element discretisation are studied, and the influence of the filter that is used in the generation process of the representative volume element is analysed. [ABSTRACT FROM AUTHOR]

Motivated by the influence of (micro-)cracks on the effective electrical properties of material systems and components, this contribution deals with fundamental developments on electro-mechanically coupled cohesive zone formulations for electrical conductors. For the quasi-stationary problems considered, Maxwell's equations of electromagnetism reduce to the continuity equation for the electric current and to Faraday's law of induction, for which non-standard jump conditions at the interface are derived. In addition, electrical interface contributions to the balance equation of energy are discussed and the restrictions posed by the dissipation inequality are studied. Together with well-established cohesive zone formulations for purely mechanical problems, the present developments provide the basis to study the influence of mechanically-induced interface damage processes on effective electrical properties of conductors. This is further illustrated by a study of representative boundary value problems based on a multi-field finite element implementation. [ABSTRACT FROM AUTHOR]

Motivated by experimental findings on deformation induced microcracks in thin metal films and by their influence on the effective macroscopic electrical conductivity, a computational multiscale formulation for electrical conductors is proposed in this contribution. In particular, averaging theorems for kinematic quantities and for their energetic duals are discussed, an extended version of the Hill–Mandel energy equivalence condition is proposed and suitable boundary conditions for the microscale problem are elaborated. The implementation of the proposed framework in a two-scale finite element environment is shown and representative boundary value problems are studied in two- and three-dimensional settings. [ABSTRACT FROM AUTHOR]

The paper describes the development of passive, chipless tags for a novel indoor self-localization system operating at high mm-wave frequencies. One tag concept is based on the low-Q fundamental mode of dielectric resonators (DR) which exhibits peak scattering at its resonance frequency. As the radar cross-section (RCS) of DRs at mm-wave frequencies is far too low for the intended application, arrays of DRs and combinations with dielectric lens and corner reflectors are investigated to boost the RCS while keeping the scattering retro-directive over wide-angle incidence. Satisfactory results are demonstrated experimentally in W-band with metal corner reflectors combined with planar arrays of DRs; the tags produce a high RCS level over a moderately broad angular range and a wide frequency range where they exhibit a notch at the resonance frequency of the dielectric resonators. These designs suffer from low coding range of 3 to 6 bit, degradations of RCS in angular range, and a difficult separation of the tag response from strong clutter. Both the suppression of large clutter interference by using time gating of the tag response and a larger coding range are promised by a chipless tag concept based on multiple high-Q resonators in photonic crystal (PhC) technology. Experimental samples are characterized as transmission resonators and as retro-directive tags at the 230 GHz band. As a concept to boost the retro-directive RCS with a truly wide-angle response, the integration of PhC resonators with a Luneburg lens is discussed. [ABSTRACT FROM AUTHOR]

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The article presents a case study of a 66-year-old male patient with acquired hemophilia A (AHA) and its first-line treatment. It discusses the inhibitor eradication prednisolone, with cyclophosphamide with dose of rituximab, responsiveness to prednisolone pulse therapy, switching of therapy to combination of bendamustine, prednisolone.

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Higher levels of fibrinogen or cholesterol were associated with improved hearing recovery in SSHL patients after treatment with HELP-apheresis (Heparin-induced extracorporeal LDL precipitation apheresis). The present trial was performed to demonstrate HELP-related effects on relevant metabolic and inflammatory parameters in the context of SSHL treatment. In the framework of a single arm non-controlled trial, we investigated the variation of metabolic and inflammatory parameters using HELP-apheresis for a defined group of 100 patients with SSHL. Based on cut off inclusion criteria (Serum LDL-cholesterol >1.6 g/l and/or fibrinogen >2.0 g/l, SSHL in minimum three frequencies more than 30 dB, time after event not longer than 6 days), the protocol followed a strict time line with one single shot HELP-apheresis and follow-up monitoring including laboratory parameters at six defined time points. If HELP-apheresis could not effect improvement of hearing on day 5, additional corticosteroid treatment was applied. Concentration of anti-inflammatory IL-10 increased while other proinflammatory parameters declined. Serum levels of all measured sterols and apolipoproteins decreased significantly. None of the investigated parameters were suitable to predict hearing improvement of the patients. Levels of fibrinogen and LDL-cholesterol were not prognostic for outcome after HELP-apheresis. A significant ( p < 0.001) increase of anti-inflammatory IL-10 after apheresis was notable, while most of the proinflammatory parameters declined. Despite the limited validity of a single arm non-controlled trial, these alterations on immune modulating factors indicate possible secondary pleiotropic effects caused by HELP-apheresis. [ABSTRACT FROM AUTHOR]

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Introduction: The purpose of this study was to evaluate the results of a contoured focal articular femoral condyle resurfacing prosthetic in the treatment of full-thickness cartilage and osteochondral defects at the medial femoral condyle of the knee beyond 5 years. Methods: In a multicenter case series, preoperative and follow-up scores of the Knee Injury and Osteoarthritis Outcome Score (KOOS), SF-36 and Tegner activity scale were evaluated. Standard radiographs were performed to evaluate the progression of osteoarthritis. Patients were also asked to report their satisfaction. Results: A total of 21 patients were included in this study. The average follow-up was 5.3 years. The average age at the time of resurfacing was 54 years. Average KOOS scores significantly ( P ≤ 0.005) improved for pain (51.1 to 77.6), symptoms (57.9 to 79.5), activities of daily living (ADL) (58.8 to 82.4), sports (26.3 to 57.8) and quality of life (QOL) (34.4 to 55.0). The Tegner activity level improved significantly ( P ≤ 0.02) from 2.9 to 4. The physical health value of the SF-36 increased by 15.2 to 46.9 compared to the preoperative value. The mental health value almost (51.2) remained unchanged. As many as 16/21 of the patients in this series were satisfied with their outcome and would have the operation again. Radiographic results demonstrated solid fixation, preservation of joint space and no change in the osteoarthritic stage. Conclusions: The device appears to be an effective reconstructive treatment option for large full-thickness cartilage and osteochondral lesions of the knee in middle-aged patients. [ABSTRACT FROM AUTHOR]

Copyright of Der Unfallchirurg is the property of Springer Nature and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Introduction. Cardiovascular morbidity and mortality is a major and still unresolved threat to patients with reduced glucose tolerance and Type 2 diabetes mellitus. In epidemiological studies, in non-diabetic subjects, post-prandial glycaemia is positively associated with the risk of diabetes, hypertension and cardiovascular events. If this epidemiological association is causal, Acarbose, which reduces post-prandial blood glucose concentrations, should result in a decrease in the risk of these events. The STOP-NIDDM trial investigated whether Acarbose reduces the risk of diabetes, hypertension and cardiovascular events. Consequently, the validity of the results of this trial is of major importance for future treatment in non-diabetic and diabetic patients. Methods. We searched various databases and the Internet for publications of the design and the results of the STOP-NIDDM trial. A systematic review of these publications was done with respect to information about potential sources of bias and contradictory information in the articles. Results. We found several serious flaws in the STOP-NIDDM study, especially selection bias, inadequate blinding, bias in data analysis and reporting, and potential sponsoring bias. Conclusions. The validity of the results of the STOP-NIDDM trial is seriously flawed. The clinical benefit of Acarbose and of the reduction of post-prandial glycaemia is unproven. [ABSTRACT FROM AUTHOR]

Neurophysiologic examinations in differential diagnosis of erectile dysfunction comprise electromyogramme of the pelvic floor, pudendal nerve terminal motor latency (PNTML) and evaluation of pudendal somatosensory evoked potentials (SSEP). We focused our interest on comparing diagnostic importance of penile and perianal pudendal nerve SSEP. We examined 20 patients suffering from erectile dysfunction and 20 patients without any manifestation of impotence. The stimulus was administered using penile ring electrodes at the base of the penis (cathode) and distally on the penis shaft (anode), as well as a perianal surface electrode applied at 3 o'clock in lithotomy position and 5 cm laterally on the gluteal skin. The potentials were recorded with intradermal needle electrodes at C[sub z]-2 cm (different) and F[sub z] (indifferent). 500 stimuli were averaged for a single tracing. The stimulus strength was set at an average of 3-4 times the stimulus threshold. Cortical latency of P 40 ranged from 39.0 to 45.6 ms (penile) and from 33.6 to 43.2 ms (perianal) in the control group, in the patient group latencies ranged from 38.8 to 51.6 (penile) and 34.0 to 44.8 ms (perianal). In two patients no potential was recordable after perianal stimulation, one patient showed a marked prolongation of the penile response with a normal perianal latency. Penile and perianal latencies of P 40 were significantly prolongued in the patient group compared to the control group (P < 0.05). The combination of penile and perianal pudendal SSEP may provide valuable additional information in differential diagnosis of erectile dysfunction, especially allowing to identify different sites of neurogenic lesions. In contrast to perianal pudendal SSEP, penile stimulation may help to discover pathologic changes in the distal course of the pudendal nerve, especially the dorsal nerve of the penis. [ABSTRACT FROM AUTHOR]

We study a multicomponent generalization of Helly's theorem. An ( n,d)-body K is an ordered n -tuple of d -dimensional sets, K= < K 1 , . . . ,K n > . A family $\cal F$ of ( n,d)-bodiesis weakly intersecting if there exists an n -point p = < p 1 , . . . , p n > such that for every $K \in {\cal F}$ there exists an index 1 $\leq i \leq n$ for which p i ∈ K i . A family $\cal F$ of ( n,d)-bodies is strongly intersecting if there exists an index i such that $\bigcap_{K\in{\cal F}} K_i \neq \emptyset$ . The main question addressed in this paper is: What is the smallest number H(n,d), such that for every finite family of convex (n,d)-bodies, if every H(n,d) of them are strongly intersecting, then the entire family is weakly intersecting? We establish some basic facts about H(n,d) , and also prove an upper bound $H(n,d)\leq (\lfloor \log_2 (n+1) \rfloor + 1)^d$ . In addition, we introduce and discuss two interesting related questions of a combinatorial-topological nature. [ABSTRACT FROM AUTHOR]

Surface impedance data at 19 and 87 GHz of high-quality epitaxial YBCO films on different substrates are compared with data for Nb3Sn films on sapphire in terms of pair and quasiparticle (qp) transport. Surface resistance Rs and penetration depth λ of YBCO are strongly affected by temperature dependent qp scattering, which is depressed in films with enhanced lattice strain. All films showed a comparable residual resistance Rres(19 GHz)∼90 μΩ constituting a qp reservoir which is likely to be caused by the electronic configuration and by impurities. Subtracting Rres from Rs (T) revealed activated behavior with a reduced energy gap Δ0/ kB Tc∼0.9 for a film on sapphire, but power-law behavior for the other films. The penetration depth did not reveal power-law dependences at T≤0.5 · Tc, but was consistent with a reduced energy gap of 0.45 for a film on MgO. The increase of λ( T) at T≥0.5 · Tc was related to qp scattering, which also caused an extremal conductivity σ1( T). A shoulder in λ( T) at T=(0.6–0.7) · Tc confirmed evidence for the existence of two superconducting bands. The magnetic-field induced recovery of λ( B) of various YBCO films hinted for an important role of magnetic scattering. The results are in contradiction to a d-wave symmetry of the order parameter, at least for the chain band. [ABSTRACT FROM AUTHOR]

We present a method which reduces a family of problems in combinatorial geometry (concerning multiple intervals) to purely combinatorial questions about hypergraphs. The main tool is the Borsuk—Ulam theorem together with one of its extensions. For a positive integer d, a homogeneous d-interval is a union of at most d closed intervals on a fixed line ℓ. Let ${\cal H}$ be a system of homogeneous d-intervals such that no k + 1 of its members are pairwise disjoint. It has been known that its transversal number $\tau ({\cal H})$ can then be bounded in terms of k and d. Tardos [9] proved that for d = 2, one has $\tau ({\cal H}) \leq 8k$ . In particular, the bound is linear in k. We show that the latter holds for any d, and prove the tight bound $\tau ({\cal H}) \leq 3k$ for d = 2. We obtain similar results in the case of nonhomogeneous d-intervals whose definition appears below. [ABSTRACT FROM AUTHOR]

A 47-year-old woman had a chondrosarcoma arise in extra-articular synovial chondromatosis near the ankle. A review of the literature suggests that this lesion is rare and that proper interpretation of histopathologic preparation of cartilage lesions can be difficult. [ABSTRACT FROM AUTHOR]

The preparation of polymer microcapsules of well defined size in the range of 10—50 µm with different shell thickness to core diameter ratios is described. An aerosol of monodisperse droplets of a homogeneous ternary liquid system which contained a hydrophobic component and a hydrophilic component dissolved in a high-volatile mutual solvent, was produced by dispersing with a vibrating-orifice aerosol generator. After the evaporation of the solvent in a nitrogen atmosphere the particles demix and form a two-phase droplet of core-shell type. These droplets were illuminated with UV light and polymerized to highly monodisperse microcapsules with a solid polymer shell and a liquid core. The properties of the resulting particles (size, size distribution, shell thickness, shape and surface characteristics) were investigated by scanning electron microscopy, Raman spectroscopy on single optically levitated particles, and confocal Raman micro spectroscopy. The microcapsules were highly monodisperse and have spherical shape. [ABSTRACT FROM AUTHOR]

The use of rotational symmetric modes of superconductive disk (ring) resonators in order to increase the power handling capability of planar filters has been proposed. Several YBCO disk resonators on LaAlO3 and sapphire substrates have been measured as one- and two ports. The unloaded Q-factor of the resonators has been measured to be greater than 105 up to the oscillating power of 50 kW. Experimental results obtained show that a disk resonator can be used as a building block for low insertion loss, sharp skirt high-power planar filters at low GHz frequency range and temperatures of around 60 K. [ABSTRACT FROM AUTHOR]

The in situ process—laser ablation in combination with thermal evaporation of Tl2O—has turned out to be a preparation method for single-phase and epitaxial TlBa2Ca2Cu3O9 (1223) thin films with Tc values up to 109 K. It was found by several groups that a partial substitution of Tl by Bi simplifies the phase development of the 1223 compound in the usual two-step process. We have investigated the influence of the Bi doping on the in situ growth. X-ray measurements show that the films consisted mainly of the 1223 compound. In 300-nm thin films there was no evidence of a Bi amount in the crystal structure, but thinner films (80 nm) show a small amount of Bi. We concluded that Bi doping supports the phase development of the 1223 compound only in an early stage of the film growth. The Bi-doped films have higher Tc values up to 114 K, higher jc values up to 6 × 105 A/cm2 (77 K, 0 T), and lower surface resistances of 56 mΩ (77 K, 87 GHz) than the undoped films. [ABSTRACT FROM AUTHOR]

Crack-free thick YBa2Cu3O7 − x films are prepared on CeO2 buffered r-cut sapphire (2 inch in diameter) with thickness up to 700 nm, smooth surfaces (“peak-to-valley” roughness <10 nm), high critical currents ( JC > 2 MA/cm2 at 77 K and 0 T), and low microwave surface resistances ( Rs(77K) ≍.4mω and Rs(4.2K) ≍.110μω at 19.15GHz) comparable to the best values reported in the literature for YBCO films on structurally better matched substrates. These thick YBCO films were able to handle high microwave power corresponding to magnetic field amplitudes ( BHF) up to 54, 37, and 17.4 mT at 4.2, 50, and 77 K, respectively, which for the lower temperatures were limited by the available power of the 25-W HF amplifier. The high-power performance, which to our knowledge belongs to the best reported so far for unpatterned YBa2Cu3O7 − x films, was achieved without any degradation of the samples despite frequent thermal cycling. [ABSTRACT FROM AUTHOR]

An anomalous magnetic field-effect has been observed in the microwave surface impedance of epitaxial YBa2Cu3O7−x films on LaAlo3 substrates. The application of dc and microwave magnetic fields up to 20 mT caused a significant decrease of microwave surface reactance X s (≤3%) and resistance R s (≤20%) at 8.5 GHz, 77 K and at 87 GHz, 4.2 K. The field effects on X s and R s s were found to correlate within the framework of the two-fluid model. The observed effect is attributed to the presence of magnetic impurities in the superconducting films, giving rise to pair breaking. Alignment of the impurity spins suppresses the spin-flip scattering rate and, as a result, leads to a recovery of microwave superconductivity. [ABSTRACT FROM AUTHOR]

The conditions for the design of compact high-power HTS filters are deduced from basic considerations, and related to the microwave properties of the HTS films and the substrates. Potential mechanisms limiting the linear microwave response of HTS films are analyzed systematically. Magnetic and thermal field breakdowns are found to confine the power handling capability to comparable field levels. While magnetic limitation is related to flux penetration at the lower critical field Bc1, thermally induced quenches occur dependent on the presence of defects and on the thermal conductivity of the substrate. The detrimental role of film inhomogeneities for the linear microwave response is confirmed experimentally for microwave fields at 19 GHz and for dc fields at 87 GHz. [ABSTRACT FROM AUTHOR]

World maps of the occurrence of VLF emissions obtained by the satellites Ariel 3 and 4 reveal maxima above industrial regions of high power consumption in North America and Euro-Asia. A study of the generation and radiation of power line harmonics indicates that these may be a major source of the observed signals. The latter propagate in the whistler mode into the geomagnetically conjugate regions in the southern hemisphere. A particularly prominent zone of emission is obtained at VLF (3.2 kHz) over North America where frequent magnetospheric wave amplification/stimulated emission, up to 50 dB and typically 10 to 20 dB above a baseline level that we ascribe to power harmonic radiation (PLHR), is obtained at invariant latitudes 45 to 55° (2 < L < 3) centred on the electron slot. It appears that PLHR may be responsible for pitch angle diffusion of energetic electrons ( E ≥ 100 keV) at large pitch angles by first-order resonance and thereby contribute to the formation of the electron slot. There is a strong seasonal variation in wave-amplification/stimulated emission which we suggest may be due to a variation in the ability of the waves to become entrapped in ducts where wave-amplification occurs through a phase-bunching process. There is a strong correlation between D and signal intensity, the latter lagging by ∼ 1-5 hr in the morning and ∼ 10 hr in the evening; here again wave-amplification appears to depend on duct formation and wave trapping therein. One or two (or multi) hop emissions occur with about equal probability at 3.2 kHz; at 9.6 kHz one hop are predominant. [ABSTRACT FROM AUTHOR]

Copyright of Der Urologe A is the property of Springer Nature and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Neocarus texanus, a 'primitive' mite, bears two pairs of eyes, which are principally similar in ultrastructure. Each eye is covered externally by a cuticular cornea. It is underlain by flat sheath cells which send extensive processes into the retina. The retina is composed of distal and proximal cells. The 20 distal cells of the anterior eye are inversely orientated and form 10 disc-like rhabdoms. They represent typical retinula cells. Each rhabdom encloses the dendritic process of a neuron, the perikaryon of which is located outside the retina (proximal cells). The significance of this cell is not known. The retina is underlain by a crystalline tapetum. In the posterior eye 14 retinula cells form 7 rhabdoms in an arrangement similar to the anterior eye. The eyes of one side of the body are located within a capsule of pigment cells. Together the axons of the distal and proximal cells form the two optic nerves, one on each side of the body. The optic nerves leave the eyes anteriorly and terminate in two optic neuropils located in the brain. From structural evidence it is concluded, that the resolution of the eyes must be rather low. The peculiar proximal cells have not been observed previously in Acari. They probably resemble at best the eccentric cells and arhabdomeric cells of xiphosurans, scorpions, whip-scorpions and opilionids. Also, inverse retinae and tapeta of the present type have not been found in Acari until now, but are present in other Arachnida. Thus the eyes of Neocarus texanus evidently represent a unique type within the Acari. [ABSTRACT FROM AUTHOR]

Organochlorine pesticide residues were determined in 168 shorebirds of three species collected at approximate bimonthly intervals during the fall and winter months of 1979-80 near Port Mansfield on the south Texas coast. The study was conducted to determine if shorebirds wintering on mudflats at the outlets of agricultural drains in Texas accumulated pesticides during this period. The predominant Organochlorine residues detected in shorebirds were DDE, dieldrin, and toxaphene. Ninety-five % of the skinned carcasses analyzed contained detectable levels of DDE, 13% contained dieldrin, and 22% contained toxaphene. DDE significantly increased in all species of shorebirds from October to December, with potentially dangerous levels accumulating in some long-billed dowitchers ( Limnodromus scolopaceus) and American avocets ( Recurvirostra americana), but DDE residues seldom exceeded 0.5 ppm in carcasses of western sandpipers ( Calidris mauri). After about two months on the study area, no further residue increases were documented. The high levels of DDE detected in a large proportion of the dowitchers, and to a lesser extent in the avocets, are near or within the range known to inhibit reproduction in some avian species. This study demonstrates that certain aquatic areas near agricultural lands on the south Texas coast may be potential threats to waterbirds eight years after the use of DDT was banned in the United States. [ABSTRACT FROM AUTHOR]

Copyright of Der Onkologe is the property of Springer Nature and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The behaviour of radio-frequency probes in a magneto-ionic environment is important in connection with their use for measurement of ionospheric parameters and in the design of aerials for rockets and satellites. The present theoretical treatment of radio-frequency probes is outlined and applied to systems of differing configurations. The difficulties which arise when the wave frequency is not large compared with the gyro-magnetic and plasma frequencies are discussed, including especially the origin of the resistive term which can be finite, even in a collisionless plasma. Some attention is given to the effect of the plasma sheath which may surround a probe system. A number of practical systems are described and the problems in interpreting impedance measurements are considered. [ABSTRACT FROM AUTHOR]

Estimates of the spatial density of interplanetary dust are derived from meteor, accretion and zodiacial cloud observations. When the most recent data are considered it is found that there is no longer any serious discrepancy between the extrapolated meteor values and those from the other sources and a density distribution is obtained which extends from meteoroids capable of producing the brightest optical meteors to particles approaching the limiting size beyond which they are removed from the solar system by solar radiation pressure. Impacts on rocket and satellite vehicles lead to much higher estimates of spatial densities and it is concluded that they originate from particles in geocentric orbits belonging to a dust cloud encompassing the earth. The evidence tends to support the view that these particles are captured from the interplanetary dust cloud rather than being produced, as suggested by Whipple, through the impact of meteorites on the moon. Some suggestions are made for the direction of future rocket and satellite investigations. [ABSTRACT FROM AUTHOR]

The article presents a response to a letter to the editor about an article on acarbose for the prevention of type two diabetes, hypertension and cardiovascular disease in subjects with impaired glucose tolerance.