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Squeeze casting is a cost-effective alternative to traditional casting and forging manufacturing processes. Commercial machines that do the job are the vertical clamping, vertical shot (VSC) type or horizontal die clamping, vertical shot type (HVSC). Automotive components produced by squeeze casting include wheels, suspension arms, cross members, brake calipers and most aluminum foundry alloys. Squeeze casting, with the aid of the partial squeeze control system (PASCON), generates ideal mechanical properties in a product which spells superior quality., Squeeze casting is becoming a valuable mass production technique for some automotive parts. Vertical indirect squeeze casting combines the advantages of low-pressure die casting (LPDC) and conventional high-pressure die casting [...]

Background: This study aimed to establish the accuracy and reproducibility of localization of intraluminal markers by laparoscopic and open techniques in a swine colorectal model, using a prototype for a novel wireless system. Methods: A prototype marker was placed into the colon of an adult pig. The surgeon was blinded to placement and localized the marker using a detection probe (3 surgeons/10 trials/2-D and 3-D systems). Results: Each surgeon was able to accurately locate the marker within 28.7 ± 20.6 (LAP) and 18.3 ± 6.7 (OPEN) sec ( p = 0.013). There were no significant differences between surgeons in localization times, regardless of experience. A 3-D interface made no difference in accuracy or time (LAP = 35 vs 28 seconds; p = NS [not significant]). Conclusions: This study demonstrates the use of a novel system for intraoperative identification of nonpalpable lesions. This technology may have important implications in the surgical management of nonpalpable tumors and in applications of interventional radiology.

The aim of this study was to assess the frequency and imaging characteristics of focal levator eventrations in patients with pelvic floor dysfunction on magnetic resonance (MRI). A review of 81 dynamic MR pelvic examinations in patients with pelvic floor dysfunction was carried out to detect and characterize focal eventrations in the levator ani muscle. These were defined as muscle outpouchings which made an angle of >180° with the remainder of the muscle and had a depth of =1 cm. Of 81 patients 11(13.5%) had focal eventrations in the levator muscle on MRI: bilateral in 2 cases, right in 5 and left in 4. There was protrusion of pelvic viscera into the eventration in 5 cases, fat in 7 and fluid in 1. Focal levator ani muscle abnormalities are not uncommon on MRI in patients with pelvic floor dysfunction. Characterization of levator muscle morphology can be useful as a research tool in this population.

Abstract Aims To report the appearances of iridocorneal endothelial (ICE) syndrome from real time, white light confocal microscopy. Methods Three consecutive patients, each with ICE syndrome, were examined prospectively. Corneal specular and confocal microscopic examinations were performed in all three patients. In the first patient, a penetrating keratoplasty was performed and the cornea was examined by light and scanning electron microscopy. No surgery was performed in the remaining two patients. Results In the first patient corneal oedema prevented endothelial specular microscopy. Confocal microscopy performed before penetrating keratoplasty successfully revealed abnormal epithelial-like endothelial cells. Histological examinations of the cornea following penetrating keratoplasty revealed the presence of multilayered endothelial cells with epithelial features (microvilli). In the remaining two patients, specular microscopy showed the presence of ICE cells with typical dark/light reversal. Confocal microscopy demonstrated groups of endothelial cells with epitheloid appearances. In all three patients, the contralateral endothelial appearance was normal by specular and confocal microscopy, except for moderate endothelial polymegathism in one patient. Epithelial-like endothelial cells were characterised by prominent nuclei on confocal microscopy. ConclusionsThe application of confocal microscopy indicates that the ICE syndrome is characterised by epitheloid changes in the endothelium. Confocal microscopy may be used to diagnose the ICE syndrome by demonstrating epithelial-like endothelial cells with hyperreflective nuclei. This technique is especially of value in cases of corneal oedema, since specular microscopy may fail to image the endothelium in such cases.

Twenty four boys with Klinefelter syndrome, 18 of whom were diagnosed prepubertally, were observed until adulthood. Onset of puberty, as judged from testicular enlargement and pubic hair development, occurred between 11 to 14 years in the above 18 patients. By the age of 17 pubic hair, penile length and height had reached the adult stage in all patients, but arrest of testicular growth was noted at midpuberty, 13 years, with maximal mean (±SD) volume attained being 3.5±1.5 ml. The first conscious ejaculation was reported to have occurred between 13 to 16 years in 10 patients and in the remaining 4 between 17 to 18 years of age. Sperm counts obtained after the age of 18 revealed azospermia or severe oligospermia in all patients except one, who had a sperm count of 30×106/ml. The hypothalamic-pituitary-gonadal axis, assessed by LH-RH and hCG stimulation tests, was found to be normal in prepuberty and during early pubertal stages. From mid-puberty the basal levels of plasma FSH and the response to LH-RH showed a gradual increase above the normal. Towards late puberty (>15 years) basal and peak levels of LH were above normal with a concomitant decrease in the basal level of testosterone and its response to hCG.

This paper describes a collection of parallel optimal control algorithms which are suitable for implementation on an advanced computer with the facility for large-scale parallel processing. Specifically, a parallel nongradient algorithm and a parallel variablemetric algorithm are used to search for the initial costate vector that defines the solution to the optimal control problem. To avoid the computational problems sometimes associated with simultaneous forward integration of both the state and costate equations, a parallel shooting procedure based upon partitioning of the integration interval is considered. To further speed computations, parallel integration methods are proposed. Application of this all-parallel procedure to a forced Van der Pol system indicates that convergence time is significantly less than that required by highly efficient serial procedures.

The levels of β-endorphin (β-E) and calcitonin were estimated in 36 samples of seminal plasma from semen of normospermic, oligozoospermic, and azoospermic origins and in pools of isolated sperm. The mean levels in plasma calculated for all samples examined were 192. ± 224 pg/ml for β-E and 754 ± 397 pg/ml for calcitonin. The amounts in sperm were as follows: for β-E in pols with sperm counts of 0.1-10 × 106/ml, 157.2 ± 99.7 pg/108 and 27.9 ± 23.6 pg/ml protein; in pols of > 10-30 × 106/ml, 71.2 ± 41.5 pg/108 and 6.5 ± 1.2 pg/mg protein; in pools of > 30-200 × 106/ml, 24.9 ± 9.7 pg/108 and 61 ± 1.9 pg/mg protein. For calcitonin the amounts were: 501.2 ± 170.8 pg/108 and 27.4 ± 21.5 pg/mg protein, correspondingly. It was suggested that β-E and calcitonin present in seminal plasma are synthesized mostly in a compartment of the male reproductive system. The high cellular β-E and calcitonin levels would be involved in the process of motility through their effect on calcium transport.

A new type of disk-lubricated bearing runs developed for use on heavy duty fans. The bearing is self-contained and requires no external source of lubricant supply. Performance tests were made on two bearing sizes, 125 mm (4.92 in.) and 254 mm (10 in.) diameter, for various bearing clearances, journal speeds, and loads. Both radial load alone and combinations of radial and thrust loads were imposed. Good correlation was obtained between the tests and the results predicted by a theoretical analysis. Many field applications have confirmed the reliability of the bearing.

In this paper we discuss the use of an ellipsoid algorithm for the determination of output feedback gains in a linear time-invariant control system. The gains are chosen to minimize a quadratic performance criterion subject to an explicit constraint on system stability. Several numerical examples are studied in which not all of the state variables are accessible. Comparisons are made between the ellipsoid algorithm approach and four other commonly employed methods of solution. The ellipsoid algorithm is shown to be practical, accurate, robust, and relatively insensitive to large errors in the initial estimates of the gains.

Direct multivariable model reference adaptive control (DMMRAC) procedures have been successfully used in continuous-time systems. Previous discrete versions of the algorithm required apriori knowledge of a stabilizing feedback gain matrix for the controlled plant and also an estimate of the ideal model following control in order to guarantee a bounded output tracking error.

This paper discusses the possible use of a recursive, approximate maximum likelihood identification algorithm, based on an anesthetic gas uptake and distribution model of the body and the lungs, to develop a continuous, noninvasive estimation scheme for the determination of cardiac output and related parameters from blood-soluble anesthetic gas concentration measurements. Considering the inhaled anesthetic gas concentration as amplitude limited, on-line computation of a sub-optimal input sequence to maximize the incremental increase in information during the next measurement period is studied. Special consideration is given to different error sources affecting the estimation scheme. Computer simulations and in-vivo experiments demonstrate that these inputs (inspired anesthetic agent concentration) are implementable and that the proposed estimation scheme can be used for on-line cardiac output determination provided that the nonestimated system parameters can be measured with sufficient accuracy.

Blurred and noisy images can often be represented as nonstationary two-dimensional (2-D) stochastic processes that can be modeled by a set of linear state equations with space-varying coefficients. This paper presents an algorithms based on the Extended Kaiman Filter,(EKF) for on line identification of nonhomogeneous image model parameters, spatialy varying blur models and nonlinear degradation models. Results show that although the EKF is effective for tracking the image and the so-called density to intensity transformation parameters, its utility for estimating blur model parameters is limited because the presence of only a stochastic forcing function prevents the incorporation of linearity assumptions.

A direct model reference adaptive control (MRAC) algorithm is used to compute the infusion of two drugs in order to control blood pressure and cardiac output in a realistic physiological nonlinear multiple-input multiple-output representation. Consideration is given to the effects of digitization, unequal output sampling rates, and to a modification to alleviate the nonsatisfaction of a positive real condition.

Summary In an attempt to define the tissue of origin of substances causing aseptic meningitis and secondary hydrocephalus after posterior fossa surgery, analysis of several marker substances from blood, brain, tumour and muscle in the CSF was performed early in seven postoperative patients. No clear pattern emerged which could relate the substances, CSF reaction, and meningeal scarring. The effects of various factors such as contrast studies, drainage, and steroids were also not clear.

Summary A delayed traumatic intracerebral haematoma (DTICH) was seen in a patient with a moderately severe head injury and disseminated intravascular coagulation and fibrinolysis (DICF) two hours after she had a normal computerized tomographic (CT) scan of the brain and five and one half hours after she was involved in a motor vehicle pedestrian accident. It is important to consider the diagnosis of DTICH in patients with head injuries who deteriorate clinically, especially if they have DICF.

Summary Patients who have suffered gunshot wounds in civilian settings, who present with posturing and in whom the bullet has passed through the geographical centre of the brain have generally not been felt to be salvageable. However, surprisingly favourable outcomes in two such patients have led us to believe that some such patients may deserve agressive treatment.

Summary Although the ultimate success of surgery depends on the use of adequate psychomotor skills, the evaluation of the abilities of a trainee and the teaching of these skills has not been systematized. The choice of a trainee in surgery should be based at least partially on his innate abilities, and his training should be begun at an appropriate level. The procedures he may do should be analyzed to determine the skills required for their performance. Then these skills should be taught specifically, initially in non-threatening situations such as laboratory settings, and their acquisition assessed so that he can be progressed to more advanced work at the appropriate time. Ultimately a decision must be made whether to train a candidate to a skill level or whether to train him for a set period and then counsel him regarding which procedures he has the skills to perform. There are well developed concepts in educational psychology that may be used in developing improved methods to assess and train prospective surgeons.

A model predictive control strategy was developed and tested on a nonlinear canine circulatory model for the regulation of hemodynamic variables under critical care conditions. Different patient conditions such as congestive heart failure, post-operative hypertension, and sepsis shock were studied in closed-loop simulations. The model predictive controller, which uses a different linear model depending on the patient condition, allowed constraints to be explicitly enforced. The controller was initially tuned on the basis of a linear plant model, then tested on the nonlinear physiological model; the simulations demonstrated the ability to handle constraints, such as drug dosage specifications, commonly desired by critical care physicians.

Inhibition of herpesvirus plaque growth was observed when herpes simplex virus (HSV)-sensitized rabbit lymphocytes were placed in contact with an HSV-infected human foreskin monolayer. This inhibition was obtained as early as 3 h when a ratio of 6 viable lymphocytes to target cells was used, and the supernatants of these cultures also demonstrated plaque size reduction when put onto newly infected cell monolayers. Interferon, which is present in this system, had no effect on HSV when tested on human foreskin monolayers, indicating that interferon was not the mechanism for plaque size reduction. Plaque growth inhibition was attributed to the T lymphocyte, because purified T cells reduced plaque growth and anti-rabbit thymocyte serum eliminated the effect of T cells. The specificity of this assay was determined by the facts that nonsensitized lymphocytes did not reduce the size of a plaque and the recognition of an infected cell by the sensitized lymphocyte was necessary for the release of a soluble mediator into the supernatant fluid. This cytotoxic lymphocyte was detected in the peripheral blood of rabbits as early as 4 days after initial corneal infection, with a maximum response at 7 to 10 days.

This paper presents a new adaptive hierarchical control technique that adjusts its structure in order to maintain good performance over a wide variation of plant operating conditions. In contrast to the conventional approach of designing a compensator based upon a single control algorithm, this method combines a range of control algorithms in a complementary manner, each of which makes different assumptions about the regulated process. The hierarchical control structure includes a fuzzy controller which requires little process knowledge in order to provide an effective control, a multiple model adaptive controller which provides credible performance when the model bank adequately spans the expected plant variations and the plant behaves reasonably close to the model on which the compensator design was based, and a direct model reference adaptive controller which assumes that the plant transfer function satisfies specific sufficiency conditions. This paper presents an application of the hierarchical control structure as a regulator for a drug delivery system.

Summary A young woman presented with a spontaneous carotid-cavernous fistula. She also had fibromuscular dysplasia of the extracranial cerebral arteries. The possible relationship of the two diseases brought up important questions concerning how to manage the patient. Treatment by obliteration of the carotid circulation on one side would be expected to increase blood flow on the other side. If the cavernous carotid artery on the second side was weakened by fibromuscular dysplasia, the increased flow might predispose to the formation of a second carotidcavernous fistula. We first attempted to avoid surgery. When progressive symptoms occurred, the cavernous sinus was obliterated with bronze wire, thus preventing venous shunting.

Summary A case of partially occluding post-traumatic thrombosis of the internal carotid artery and secondary embolism of the middle cerebral artery is reported. The patient was treated with Thrombolysin with coincident resolution of clinical symptoms and signs and clearing of the lesions on arteriography. This may have been fortuitous.

Initiation of T-cell antigen receptor (TCR) signaling is dependent upon the activity of protein tyrosine kinases. The Src family kinase Lck is required for the initial events in TCR signaling, such as the phosphorylation of the TCR complex and the activation of ZAP-70, but little is known of its role in downstream signaling. Expression of a mutated form of Lck lacking SH3 domain function (LckW97A) in the Lck-deficient T-cell line JCaM1 revealed a requirement for Lck beyond the initiation of TCR signaling. In cells expressing LckW97A, stimulation of the TCR failed to activate the mitogen-activated protein kinase (MAPK) pathway, despite normal TCR zeta chain phosphorylation, ZAP-70 recruitment, and ZAP-70 activation. Activation of extracellular signal-regulated kinase (ERK) and MAPK kinase (MEK), as well as the induction of CD69 expression, was greatly impaired in JCaM1/LckW97A cells. In contrast, the phosphorylation of phospholipase Cgamma1 (PLCgamma1) and corresponding elevations in intracellular calcium concentration ([Ca2+]i) were intact. Thus, cells expressing LckW97A exhibit a selective defect in the activation of the MAPK pathway. These results demonstrate that Lck has a role in the activation of signaling pathways beyond the initiation of TCR signaling and suggest that the MAPK pathway may be selectively controlled by regulating the function of Lck.

A multiple model image estimation technique with its required steps of model design, edge detection, filtering, and model tuning is presented and compared with a moving window continuously adaptive technique. In the multiple model technique a new probabilistic decision rule is used for edge detection, while two dimensional reduced update Kalman filters perform the image estimation. In the moving window technique the minimization of a filtering error index and of a smoothing error index is used to identify the unknown parameters of fixed structure predictor-corrector type filters that perform the image estimation. Processed images are shown as examples.

The role of model reference adaptive control is under consideration for a computer based feedback system which will regulate the infusion rate of a drug (nitroprusside) in order to maintain desired blood pressure. Because parameters are different for each patient and furthermore are variable with time, an adaptive algorithm is desirable for maintaining both steady state and transient specifications. To this effect, computer simulation has shown that direct (or implicit) model reference procedures might be successfully applied to the control of blood pressure despite the uncertainty in the delays, time constant and gains. Additional efforts concerned with the actual demonstration of these concepts on dogs have further supported the role of adaptive control for blood pressure regulation.

Seventy specimens of human seminal plasma obtained from azo-ospermic, oligospermic, and normos-permic men were tested for immunosuppressive activity on normal donor lymphocytes. Spermine and spermidine levels in acidic extracts were determined in 32 specimens of seminal plasma from the three groups. The original seminal plasma as well as the neutralized spermine extracts were examined for their effect on the functional activity of the lymphocytes. Seminal plasma obtained from the normosper-mic and oligospermic semen showed significant immunosuppressive activity, whereas no immunosuppressive activity was induced by seminal plasma from azo-ospermic semen. The latter finding was in accordance with the low spermine levels in azo-ospermic semen, which were about 50% of those found in normospermic and oligospermic seman. Acidic extraction of the seminal plasma of azo-ospermic origin resulted in an increase in spermine levels and also in immunosuppressive activity, demonstrating that in azo-ospermic men spermine is bound probably to a protein and is released after acidification, exerting its immunosuppressive activity only when unbound.

Abstract Aims To report the appearances of cornea guttata and Fuchs' endothelial dystrophy from white light confocal microscopy. Methods Seven eyes of four consecutive patients with cornea guttata were prospectively examined. Of the seven eyes, three also had corneal oedema (Fuchs' dystrophy). In vivo white light tandem scanning confocal microscopy was performed in all eyes. Results were compared with non-contact specular microscopy. Results Specular microscopy was precluded by corneal oedema in one eye. In the remaining six eyes, it demonstrated typical changes including pleomorphism, polymegathism, and the presence of guttae appearing as dark bodies, some with a central bright reflex. In all seven eyes, confocal microscopy revealed the presence of round hyporeflective images with an occasional central highlight at the level of the endothelium. Changes in cell morphology and size were readily appreciated. Conclusion By comparison with specular microscopy, the hyporeflective images with an occasional central highlight seen on confocal microscopy are consistent with the presence of guttae. Confocal microscopy may confirm the diagnosis of cornea guttata and Fuchs' endothelial dystrophy by demonstrating the presence of guttae. This technique is especially valuable in cases of corneal oedema, where specular microscopy may fail to visualise the endothelium. However, specular microscopy should remain the method of choice to evaluate the endothelium, principally because it is easier to use.

Summary Four per cent (38) of 881 head injured patients developed known subdural hygromas. Their times of onset and course were variable. However, only two large hygromas seemed clinically significant. Hygromas were more frequent when intracranial pressure monitors were placed, possibly due to opening of the arachnoid, particularly if intracranial pressure was low. But, of course, monitors were only inserted in more severely injured patients. The use of Richmond bolts to drain subdural hygromas in a controlled fashion while monitoring intracranial pressure is suggested.

Summary “High spinal” (cervical and upper thoracic) dysrhaphism usually involves either a meningocele or a dermal sinus tract. These high spinal lesions can have a complex intradural anatomy at the level of the lesion (as this case reports) and are associated with an increased incidence of lower spinal occult dysrhaphic anomalies. It is therefore recommended that patients with “high spinal” dysrhaphism undergo radiological evaluation of the entire spine to identify those patients with intradural anomalies, define the anatomy for surgery, and investigate the lower spine for associated occult anomalies.

Summary A unique patient with bilateral subdural haematomas with localized subdural membranes on one side is reported. Serial CT scans suggested that the membranes resolved spontaneously after drainage of the haematoma. The pathophysiology of subdural haematoma and the value of CT scanning in postoperative follow-up are discussed, especially in regard to learning more about the optimal treatment in this still somewhat enigmatic problem.

Summary: The solubility of hydroxyapatite was examined in calcium phosphate mixtures produced by combining Ca(OH)2 and H3PO4 in varying proportions under a wide variety of conditions. Analyses of supernatants for calcium, phosphorus, and pH provided the data for solubility calculations. Alteration of the solid/liquid ratio by removing supernatant or by evacuating water from equilibrated mixtures had little effect on the solubility product. However, when precipitates separated from some mixtures were reequilibrated at various solid/solution ratios in either water, acetate buffer, or supernatants obtained from previous equilibrations, incongruent solubility was demonstrated and was attributed to the formation of other calcium phosphate phases which coated the apatite. The experiments indicated that hydroxyapatitie has a thermodynamic solubility product between 10−57 and 10−60, but the exact value is difficult to determine because of the formation of surface coats.

Precipitates formed over a 10 day period by adding variable amounts of Ca(OH)2 to H3PO4 were examined chemically and by X-ray diffraction in order to determine and to relate the crystallographic changes observed during calcium phosphate formation in this system to those seen previously in dental plaque. In the lower Ca(OH)2/H3PO4 ratio mixtures the initial precipitates were amorphous or poorly crystalline. The latter deposits showed an apatite-like diffraction pattern which changed to brushite and decreased in Ca/P ratio from approximately 1.2–1.0. Since the amorphous precipitates showed a similar decrease in the Ca/P ratio and a transient appearance of apatite, it was suggested that these initial precipitates, like the poorly crystalline deposits, may contain brushite amorphous to X-rays. Precipitates from the higher Ca(OH)2/H3PO4 ratio mixtures changed from a poorly crystalline to a more crystalline apatite and the Ca/P ratio remained fairly constant. The relation between the pH, Ca and P on the one hand and the brushite and apatite contents and the pattern of crystallization of the precipitates on the other was strikingly similar to the same relationship observed earlier in dental plaque in situ, suggesting that the system used in this study could be used to study certain aspects of plaque mineralization in vitro.

The epiphenomena that seem to cause deterioration and death after spontaneous interacerebral hematoma (SICH) might best be studied in an animal model. Therefore, the principles for developing such a model and techniques to study these phenomena were evaluated. Animals will tolerate injection of 3%–5% of their brain volume with a high proportion of clots. Fluorescein can be used to study the blood-brain barrier, and gravimetry to study edema. Others have found that injection of a paraffin/oil mixture can be employed for a control model. Refinement of the fluorescein technique, development of a primate model, and directions for future research are suggested.

Treatment of established experimental keratitis caused by herpes simplex virus with 9-beta-d-arabinofuranosyladenine 5'-monophosphate (Ara-AMP) or 9-beta-d-arabinofuranosylhypoxanthine 5'-monophosphate (Ara-HxMP) showed that the Ara-AMP, in a concentration of 2 or 20%, had a significant effect on the keratitis but that 0.4% Ara-HxMP showed only minimal activity. Ara-AMP was also effective in the treatment of idoxuridine-resistant keratitis. No local toxicity with a high concentration (20%) of Ara-AMP was seen, but the duration of therapy was brief.

Model reference controllers Lave been developed for distributed parameter systems (DPS) and applied to the SCCLE roll beam, mode. equation. When the true partial eifferential. equation representation is used, the resulting control is finite dimensional but defined by an, infinite series which must be trurcatec for application. when a large but finite dimensional approximation to the DPS is used, the resulting control will be finite dimensional, but possibly not adequately representative for the actual DPS.

Simple adaptive control procedure which do not require explicit parameter identification were recently shown to be fitted for control of flexible structures. However, the resulting adaptive control system may diverge when confronted with finite sensors and actuators dynamics, or with parasitic disturbances