Vlsi architecture of a smds/atm router

This paper presents a set of custom components used to implement a connectionless service on top of an atm network. In a first part, the chosen architecture is described, together with the level of performance requested. Then we analyze how the architecture and other constraints influence the chip partitioning. Finally the three custom devices developed for this application are succinctly described.     

Design and implementation aspects of an experimental C++ programming environment

A good programming language alone is not sufficient for economic software production. The programming environment has a significant influence on the productivity of software engineers. Providing a programmer with information about an object-oriented software system requires extracting information from the source code, e.g. class, method and variable names. We use separate structure files for holding this information and take advantage of proven tools such as make and the C preprocessor for keeping the structure files up to date and for processing software systems that heavily use macros. In this paper we describe the concepts used for comfortable processing of C++ software systems, and discuss interesting design and implementation aspects, including structure files, the applied make mechanism and the exploitation of the C preprocessor.     

Evaluation of polymerase chain reaction amplification of Mycobacterium leprae-specific repetitive sequence in biopsy specimens from leprosy patients

Biopsy specimens were obtained from 102 leprosy patients before chemotherapy and examined by polymerase chain reaction (PCR) using the primers amplifying the 372-bp DNA of a repetitive sequence of Mycobacterium leprae. The PCR results were then compared with bacterial indices (BI) of slit-skin smears and biopsy specimens. The intensities of DNA bands were in general correlated with the numbers of acid-fast bacilli, and even a sample with only one organism gave a PCR positive result. Ten 5-micron sections from each frozen tissue sample were pooled and processed for DNA preparation. PCR was positive for 11 (73.3%) of 15 biopsy specimens with BI of 0 determined for the paraffin sections from the same biopsy samples. PCR also gave positive results for 84 (96.6%) of 87 BI positive biopsy samples. Although the difference in overall results between the two methods was not statistically significant, PCR seemed to have an advantage over microscopic examination in detecting M. leprae in biopsy specimens negative for acid-fast bacilli. Further evaluation of PCR using more specimens from leprosy patients who are bacteriologically negative is warranted to ensure PCR's advantage over the conventional microscopic examination for the diagnosis of leprosy.     

Frequency of prolonged remission duration after high-dose cytarabine intensification in acute myeloid leukemia varies by cytogenetic subtype

Advances in the treatment of acute myeloid leukemia (AML) have occurred with the introduction of new therapies including high-dose cytarabine and the identification of powerful prognostic factors such as cytogenetics that predict for long-term outcome. To date, the prognostic impact of cytarabine dose escalation within various cytogenetic groups of AML has not been assessed. We describe 285 newly diagnosed patients with primary AML who had adequate karyotypes and were enrolled on a prospective Cancer and Leukemia Group B cytogenetic study. All patients were randomly assigned to postremission treatment with standard-, intermediate-, or high-dose cytarabine intensification. Patients were categorized to one of three cytogenetic groups: (a) core binding factor type [(CBF); ie., t(8;21) inv(16), t(16;16), and del(16)]; (b) normal; and (c) other abnormality karyotype. An evaluation of these patients after a median follow-up time of over 7 years was performed to determine the relationship of intensification to outcome by cytogenetic group. Patients included 57 patients with CBF AML, 140 patients with normal karyotype AML, and 88 patients with other cytogenetic abnormalities. The treatment outcome of CBF AML patients was superior, with an estimated 50% still in complete remission (CR) after 5 years as compared with 32 and 15% for patients with normal karyotype AML and other abnormality AML, respectively (P < 0.001). Univariate analysis showed the following nonkaryotype factors to predict a prolonged CR duration: (a) younger age (P < 0.008); (b) lower leukocyte count (P=0.01); (c) the presence of Auer rods (P=0.004); (d) a lower percentage of bone marrow blasts (P=0.001) at the time of diagnosis, (e) and a higher postremission cytarabine dose (P < 0.001). The impact of cytarabine dose on long-term remission was most marked (P < 0.001) in the CBF AML group (after 5 years, 78% of those with a dose of 3 g/m2 were still in CR, 57% of those with a dose of 400 mg/m2 were still in CR, and 16% of those with a dose of 100 mg/m2 were still in CR) followed by normal karyotype AML (P=0.01; after 5 years, 40% of those with a dose of 3 g/m2 were still in CR, 37% of those with a dose of 400 mg/m2 were still in CR, and 20% of those with a dose of 100 mg/m2 were still in CR). In contrast, cytarabine at all doses produced only a 21% or less chance of long-term continuous CR for patients with other cytogenetic abnormalities. A multivariate analysis of CR duration assessed the independent impact of each of these variables on cure. Significant factors entering this model in descending order of importance were cytogenetic group (CBF > normal > other abnormality; P=0.00001), cytarabine dose (3 g/m2 > 400 mg/m2 > 100 mg/m2; P=0.00001), logarithm of leukocyte count at the time of diagnosis (P=0.0005), and histological subtype of AML (P=0.005). This study demonstrates that the curative impact of cytarabine intensification varies significantly among cytogenetic groups and results in a substantial prolongation of CR among patients with CBF and normal karyotypes, but not in those with other karyotypic abnormalities. These findings support the use of pretreatment cytogenetics in risk stratification of postremission AML therapy.     

Prognostic importance of mutations in the ras proto-oncogenes in de novo acute myeloid leukemia

Mutations of the N- and K-ras genes are the most frequent genetic aberrations in acute myeloid leukemia (AML) and their detection in preleukemic conditions such as the myelodysplastic syndrome (MDS) suggests a role in the earliest phases of leukemogenesis. Despite these observations, little is known about the clinical importance of ras mutations in AML. We studied the clinical impact of ras mutations in 99 patients with de novo AML. All patients were treated in two prospective multicenter trials. The polymerase chain reaction was used to amplify areas surrounding the codons 12, 13, and 61 of the three ras genes N-, K-, and H-ras from DNA from bone marrow cells, ras mutations were detected by an algorithm based on allele-specific oligonucleotide hybridization. Eighteen of 99 (18%) patients harbored mutations in either N- or K-ras. All of the observed mutations occurred in N-ras (N = 10) and K-ras (N = 5) or concurrently in both N- and K-ras (N = 3). There were no significant differences between ras-negative and ras-positive patients according to age, sex, blood counts, cytogenetic abnormalities, or French-American-British classification. However, univariate analysis suggested a longer survival in ras-positive patients (P = .11). When adjusted for age, which was the most important factor affecting outcome, the presence of a ras mutation emerged as a significant predictor for improved survival (P = .03) and along with lower bone marrow blast counts (P = .02) and better cytogenetic category (P = .01). However, the presence of an aberrant ras allele was strongly correlated with lower bone marrow blast counts (P = .007). Thus, whether a mutation in the N-ras or K-ras proto-oncogenes directly affects treatment outcome or indirectly through an association with lower leukemic burden remains to be determined. Nevertheless, these findings counter the prevailing bias that oncogene mutations lead to more aggressive behavior in human malignancies.     

An analytical technique for the derivation of the delay performance of ATM switches with multiserver output queues

In this paper, a discrete-time multiserver queueing system with infinite waiting room and general independent arrivals is considered. The delay performance of such a system, under a first-come-first-served queueing discipline, is evaluated by means of a purely analytical technique. Specifically, explicit formulae are derived for such quantities as the probability generating function, the mean value and the variance of the delay. The results of the study are useful, for instance, in the context of fast packet switching with output queueing, where the switching elements have their output ports organized in groups, each group corresponding to a separate output queue.     

Non-pigmented extrabulbar sarcomas of the eye-region (author's transl)

The authors report on 30 cases with non-pigmented extrabulbar sarcomas of the eye-region which occurred in our clinic within the period of 1955 till 1975. The primary sarcomas of the orbit predominate with 11 cases over the secondary involvement with 9 cases. More seldom (5 cases) is the involvement of the lids and the epibulbar space. The various groups of lymphosarcoma predominate with 16 cases over the spindle-cell sarcoma with 6 cases. The age distribution shows that these tumors prefer the first three decades and the fifth and the following decennia. The prognosis is bad for the conservation of the eye as well as for the preservation of life. With reference to the localisation the distribution at the time of the beginning of the therapy as well as the histological findings an intensive therapy (operation, radiation, chemo-therapy) has to be accomplished.     

On the influence of measurement errors in the kinematic analysis of cams

This work deals with the influence of construction and measurement errors on the accelaration law of planar cams. For this purpose a computer program is described which, using as an input the polar coordinates of the real profile, gives as output the lift and accelaration laws. These calculated values may be compared with the theoretical ones. The influence of measurement errors is investigated and a formula that allows a choice of the optimum computational step is derived.     

Receiver-initiated communication with ST-II

As part of its work on the Heidelberg Transport System (HeiTS) for multimedia communication, the IBM European Networking Center (ENC) has implemented the Experimental Internet Stream Protocol, Version 2 (ST-II). ST-II is a connection-oriented internetworking protocol for multiple-destination communication of real-time data such as digital audio and video. Although ST-II fits well into typical multimedia application scenarios, some functions are still missing No mechanisms are provided for receiver-initiated communication, allowing receivers to join streams, specify their quality of service (QOS) requirements, or initiate stream establishment and resource reservation. In this paper, we present some extensions to tile protocol that make it fulfill the receivers' needs move adequately. Our approach allows intermediate nodes to execute stream management functions on behalf of the sender. This way, the protocol scales better with the number of receivers per stream, as the origin does not need to track every target.     

The Lowest Singlet and Triplet States of o-Benzyne: Spin-Coupled Interpretation of the Electronic Structure at CAS SCF Equilibrium Geometries

The electronic structure of the X̃¹A₁ and ã³B₂states of o-benzyne is analyzed by means of spin-coupled (SC) wave functions involving eight active orbitals: two at the dehydro centers, in the plane of the ring, and six π orbitals, inherited from benzene. The equilibrium geometries of the two states, at which all calculations have been carried out, result from separate full geometry optimizations employing ‘8 in 8’ complete active space self-consistent field (CAS SCF) wave functions incorporating an analogous core-valence partitioning. The diradical character of the ground state of o-benzyne, as approximated by the singlet SC wave function, is reflected in the low value of the overlap (0.46) between the two in-plane sp²-like SC orbitals at the dehydro centers, which are just 1.274 Å apart, and in the nonnegligible extent of triplet coupling between the spins of the electrons in these orbitals — ca. 6.4% of the total spin function for the valence electrons (expressed in the Serber spin basis) is made up of spin eigenfunctions, in which these electrons enter as a triplet pair. The geometry of the ground state is found to have an aryne-like character, which is further confirmed by the pattern of alternation of the overlaps between neighboring 71 valence orbitals, and by the domination of the total spin function for the valence electrons (expressed in the Rumer spin basis) by the spin-coupling patterns corresponding to an arynic structure.