Aarskog syndrome: report of a family with review and discussion of nosology

Five individuals in one family, including dizygotic male twins, a half brother and their mother, had Aarskog syndrome (AS). Phenotypic variability is wide not only between mother and sons but also between sibs. Collectively, the affected relatives have the full spectrum of findings seen in AS. Based on analysis of this family and others from the literature, we derive primary and secondary diagnostic criteria for AS. Primary criteria include: short stature, hypertelorism, short nose with anteverted nares, maxillary hypoplasia, a crease below the lower lip, mild interdigital webbing with short and broad hands, short fifth finger with clinodactyly, and shawl scrotum. Secondary criteria include: abnormal auricles with fleshy lobules, posteriorly angulated ears, widow's peak, ptosis, downward slant of palpebral fissures, joint hyperextensibility, broad feet with bulbous toes, cryptorchidism, inguinal hernia, and prominent umbilicus. Literature pertaining to the clinical manifestations and genetics of AS is reviewed and nosology of similar syndromes is discussed.     

An analysis of frequency and amplitude effects on corrosion fatigue crack propagation in Ti-8Al-1Mo-1V

Crack growth rates were measured in Ti-8Al-1Mo-1V, which exemplifies titanium alloys susceptible to transgranular stress-corrosion cracking (SCC). A wide stress intensity amplitude (δK) range, withR = 0, was employed at ½ to 30 cps in H₂O, 3 ½ pct NaCl solution, and methanol; at 10 to 30 cps in air; and at 20 to 30 cps in vacuum, the reference environment. Crack growth was augmented by two kinds of environmental effects. The first, Type A corrosion fatigue (cyclic SCC), was effective at low frequencies in the liquid environments when K_max≥ K_Iscc, intensified with increasing amplitude, but diminished with increasing frequency. In addition to fatigue striations, cleavage on a plane 15 deg from (0001)_α was observed. The second kind, Type B corrosion fatigue, was effective at low amplitudes and in all the environments, diminished at higher amplitudes, was unaffected by changes in cyclic frequency, and was not related to the SCC susceptibility of the alloy. Striated cleavage facets on (0001)_α, and on a plane 15 deg from (0001)_α occurred at low amplitudes, while ordinary ductile striations occurred at higher amplitudes. Fatigue in vacuum did not produce fractographic fatigue striations.     

Convergent solution bounds for linear elliptic boundary value problems of monotone kind

We present a method for the construction of pointwise bounds for the solutions of linear elliptic boundary value problems by means of finite-element-functions. It is based on generalized monotonicity theorems (Collatz [4], Werner [13]). The computation of bounds is reduced to the solution of two finite linear optimization problems by a special discretization. We prove convergence and present numerical examples.     

Bounds on achievable performance in the identification and adaptivecontrol of time-varying systems

Treats the identification and adaptive control of time-varying linear systems. For linear systems with a Gauss-Markov parameter process a global lower bound on the mean square error is obtained which is valid for any causal parameter estimator. A similar lower bound is obtained for any causal, one step-ahead predictor. These bounds are applied to the adaptive control of time-varying systems to obtain a lower bound on closed-loop mean square performance for any causal control law. For a specific control law, mean square stability is established, and through simulations it is seen that the performance nearly meets the theoretical lower bound     

Programmed cell death and radioresistance

Whereas apoptosis is a critical mode of cell deletion in normal organism development, apoptotic cells are also observed in tumors, especially following cytotoxic treatments, leading to questions about their role in tumor response to therapy. We have conducted a series of studies using murine tumor models and found that the ability of the tumor cells to undergo apoptosis correlates with tumor response to radiation. The best correlation was with the pretreatment apoptotic index, suggesting that apoptosis in some tumors may govern radiocurability by regulating the number of tumor clonogens. However, other roles for apoptosis in tumor response to radiation have not been ruled out. One of the important observations that has come from this work has been the heterogeneity in apoptosis propensity both within the cell population of a given tumor and among different types of tumors. Such findings underscore the fact that apoptosis is under complex genetic control and that some of the same oncogenes and tumor suppressor genes that are responsible for tumor initiation and progression to malignancy also dictate the apoptotic response to treatment. Understanding the biochemical and molecular pathways that govern this process may ultimately allow the development of strategies for modulating apoptosis for therapeutic benefit.     

Robust Measurement-Based Admission Control Using Markov's Theory of Canonical Distributions

This paper presents models, algorithms and analysis for measurement-based admission control in network applications in which there is high uncertainty concerning source statistics. In the process it extends and unifies several recent approaches to admission control. A new class of algorithms is introduced based on results concerning Markov's canonical distributions. In addition, a new model is developed for the evolution of the number of flows in the admission control system. Performance evaluation is done through both analysis and simulation. Results show that the proposed algorithms minimize buffer-overflow probability among the class of all moment-consistent algorithms     

Comparative toxicity of ten organic chemicals to ten common aquatic species

The susceptibilities of 10 aquatic organisms to 10 organic chemicals were determined using lethality tests. The species included six fishes, two crustaceans, a chironomid and an amphibian. The chemicals were selected to span the toxicity range from 26 g l⁻¹ to 1 μg l⁻¹ and include chemicals which were lethal by four modes of toxic action. There was no consistent relative susceptibility among the test species because the sensitivity to specific modes of toxic action varied among the chemicals. Nonetheless, the toxicities of the chemicals to any given species were highly correlated to the toxicities to other species, particularly among fishes. The 96-h median lethal concentration (LC₅₀) of the chemicals to rainbow trout (Salmo gairdneri) could be estimated from the 96-h LC₅₀ with fathead minnows (Pimephales promelas) with a correlation coefficient greater than 0.99. Equations for estimating the lethal concentration of chemicals with each species from the 96-h LC₅₀ for fathead minnows are presented.     

Recurrence times of buffer overflows in Jackson networks

The estimation of the statistics of buffer overflows in networks of queues by means of simulation is inherently costly, simply because of the rarity of these events. An alternative analytic approach is presented, with very low computational cost, for calculating the recurrence time of buffer overflows for Jackson networks in which the recurrence times of buffer overflows in a network are expressed in terms of the recurrence times for overflows of individual buffers, isolated from the network. This result is applied to the buffer allocation problem for queueing networks, providing extensions and further justification for a previously derived heuristic approach to this problem     

Effect of hydrogen on fracture and inert-environment sustained load cracking resistance of α- β titanium alloys

The fracture toughness and resistance to inert-environment sustained load crack propagation of α-β titanium alloys are usually reduced by increased hydrogen contents. The range of hydrogen contents over which either fracture toughness or threshold stress intensity for sustained load cracking was observed to decrease with hydrogen content is small (0 to 50 ppm) for Ti-6 Al-4 V, but further increases in hydrogen content can cause an increase in cracking rates. Sustained load crack propagation is characterized by a mixture of microvoid coalescence with cleavage, usually on a plane 12 to 15 deg from {0001} of the hep α phase with some {000l} cleavage. Cleavage apparently initiates ahead of the main crack front within a grains, usually near apparent α-β interfaces. Atmospheric moisture is inert with respect to sustained load cracking, that is, it does not cause stress corrosion cracking. Sustained load cracking was demonstrated in Ti-8 Al-1 Mo-1 V, Ti-6 Al-6 V-2 Sn, and several grades of Ti-6 Al-4 V.