Greedy hot-potato routing on the two-dimensional mesh

Summary We propose hot-potato (or, deflection) packet routing algorithms on the two-dimensional mesh. The algorithms are strongly greedy in the sense that they attempt to send packets in good directions whenever possible. Furthermore, the routing operations are simple and independent of the time that has elapsed. The first algorithm gives the best evacuation time known for delivering all the packets to their destinations. A batch ofk packets with maximal source-to-destination distanced _max is delivered in 2(k-1)+d _max. The second algorithm improves this bound tok+d _max when all packets are destined to the same node. This also implies a new bound for the multitarget case, which is the first to take into account the number of in-edges of a node. The third algorithm is designed for routing permutations with source-to-destination distance at most three, in which case the algorithm terminates in at most seven steps. We also show a lower bound of five steps for this problem. Ishai Ben-Aroya received the B.A. and M.Sc. in computer science from the Technion (Israel Institute of Technology). He is currently working with Microsoft Israel R&D group. His main interests include Routing Algorithms, Cryptography and Computer Security. Tamar Eilam received the B.A. degree in Computer Science from the Technion IIL in 1995, and is currently studying towards her M.A. degree. Assaf Schuster received his B.A., M.A. and Ph.D. degrees in Computer Science from the Hebrew University of Jerusalem (the last one in 1991). He is currently a lecturer at the Technion IIL. His main interests include Networks and Routing Algorithms, Parallel and Distributed Computation, Optical Computation and Communication, Dynamically Reconfiguring Networks, and Greedy Hot Potato Routing.This work was supported in part by the French-Israeli grant for cooperation in Computer Science, and by a grant from the Israeli Ministry of Science. An extended abstract appeared in proc. 2nd European Symposium on Algorithms, September 1994     

Unilateral total lobectomy: is it sufficient surgical treatment for patients with AMES low-risk papillary thyroid carcinoma?

BACKGROUND: Controversy continues regarding the optimal extent of primary thyroid resection in most patients with papillary thyroid carcinoma (PTC), who are at minimal risk of cause-specific mortality (CSM). This study was designed to compare CSM and recurrence rates after either unilateral lobectomy (UL) or bilateral lobar resection (BLR) in patients with PTC considered low risk by AMES criteria. METHODS: Outcome was studied in 1685 patients initially treated during 1940 through 1991 and followed for up to 54 postoperative years (mean, 18 years). One thousand six hundred fifty-six patients (98%) had complete primary tumor resection; 634 (38%) had involvement of regional nodes. One hundred ninety-five patients (12%) had UL; BLR accounted for 1468 (near-total 60%; total thyroidectomy 18%). RESULTS: Thirty-year rates for CSM and distant metastasis were 2% and 3%, respectively. Twenty-year rates for local recurrence and nodal metastasis were 4% and 8%, respectively. There were no significant differences in CSM or distant metastasis rates between UL and BLR (P > .2). After UL, 20-year rates for local recurrence and nodal metastasis were 14% and 19%, significantly higher (P = .0001) than the 2% and 6% rates seen after BLR. CONCLUSIONS: UL was not associated with higher CSM rates, but it was associated with a significantly higher risk of locoregional recurrence. Thus BLR probably represents a preferable initial surgical approach to patients with low-risk PTC.     

Hearing and Sj?gren's syndrome

Immune sensorineural hearing loss is manifested in several systemic immune diseases. Although hearing loss has been previously documented in patients with Sj?gren's syndrome (SS), the effect of SS on hearing is unclear. This prospective study was designed to assess the presence of hearing loss in 14 patients with SS and, if sensorineural hearing loss was present, to determine if the hearing loss was immune-mediated. Patients were evaluated with basic audiologic tests as well as for cellular immune inner ear reactivity as measured by the lymphocyte transformation test (LTT). Three patients had evidence of sensorineural hearing loss. Two patients had a positive LTT without evidence of sensorineural hearing loss. This preliminary study suggests that SS may not directly cause sensorineural hearing loss, immuno-mediated or otherwise.     

Inversin, a novel gene in the vertebrate left-right axis pathway, is partially deleted in the inv mouse

A DNA fragment containing the recA gene of Gluconobacter oxydans was isolated and further characterized for its nucleotide sequence and ability to functionally complement various recA mutations. When expressed in an Escherichia coli recA host, the G. oxydans recA protein could efficiently function in homologous recombination and DNA damage repair. The recA gene's nucleotide sequence analysis revealed a protein of 344 amino acids with a molecular mass of 38 kDa. We observed an E. coli-like LexA repressor-binding site in the G. oxydans recA gene promoter region, suggesting that a LexA-like mediated response system may exist in G. oxydans. The expression of G. oxydans recA in E. coli RR1, a recA+ strain, surprisingly caused a remarkable reduction of the host wild-type recA gene function, whereas the expression of both Serratia marcescens recA and Pseudomonas aeruginosa recA gene caused only a slight inhibitory effect on function of the host wild-type recA gene product. Compared with the E. coli RecA protein, the identity of the amino acid sequence of G. oxydans RecA protein is much lower than those RecA proteins of both S. marcescens and Pseudomonas aeruginosa. This result suggests that the expression of another wild-type RecA could interfere with host wild-type recA gene's function, and the extent of such an interference is possibly correlated to the identity of the amino acid sequence between the two classes of RecA protein.     

A Scalable Parallel Algorithm for Reachability Analysis of Very Large Circuits

This paper presents a scalable method for parallelizing symbolic reachability analysis on a distributed-memory environment of workstations. We have developed an adaptive partitioning algorithm that significantly reduces space requirements. The memory balance is maintained by dynamically repartitioning the state space throughout the computation. A compact BDD representation allows coordination by shipping BDDs from one machine to another. This representation allows for different variable orders in the sending and receiving processes. The algorithm uses a distributed termination protocol, with none of the memory modules preserving a complete image of the set of reachable states. No external storage is used on the disk. Rather, we make use of the network, which is much faster.We implemented our method on a standard, loosely-connected environment of workstations, using a high-performance model checker. Initial performance evaluation of several large circuits shows that our method can handle models too large to fit in the memory of a single node. The partitioning algorithm achieves reduction in space, which is linear in the number of workstations employed. A corresponding decrease in space requirements is measured throughout the reachability analysis. Our results show that the relatively slow network does not become a bottleneck, and that computation time is kept reasonably small.     

Fiber scaffolds of polysialic acid via electrospinning for peripheral nerve regeneration

Fiber scaffolds of bioactive polysialic acid have been prepared via electrospinning for peripheral nerve regeneration. The diameter, morphology and alignment of fibers in scaffolds were adjusted by variation of electrospinning parameters, which are decisive for the cell-scaffold interaction. Due to the high water solubility of polysialic acid (poly-α-2,8-N-acetylneuraminic acid) a photoactive derivative (poly-α-2,8-N-pentenoylneuraminic acid) was used to obtain stable fiber scaffolds in water by photochemical crosslinking. At the optimized fiber scaffolds good cell viability and directed cell proliferation along the fibers was achieved by cell tests with immortalized Schwann cells.     

Electromagnetic simulation of bonding wires and comparison withwide band measurements

Several typical bonding wire configurations have been measured in a frequency range up to 20 GHz using a vector network analyzer. Based on scanning electron microscope (SEM) pictures all bonding wires have been discretized and orthogonal grids suitable for electromagnetic simulation have been generated. Full wave finite difference time domain (FDTD) simulations as well as static and quasi static inductance extraction using a new Monte Carlo technique and FastHenry as well as capacitance extraction with a finite element method have been carried out. Numerical results are compared to measured scattering parameters and their quality and frequency dependence is discussed. All simulation techniques are evaluated with respect to their computational effort     

The gene, ialA, associated with the invasion of human erythrocytes by Bartonella bacilliformis, designates a nudix hydrolase active on dinucleoside 5'-polyphosphates

ialA, one of two genes associated with the invasion of human red blood cells by Bartonella bacilliformis, the causative agent of several diseases, has been cloned and expressed in Escherichia coli. The protein, IalA, contains an amino acid array characteristic of a family of enzymes, the Nudix hydrolases, active on a variety of nucleoside diphosphate derivatives. IalA has been purified, identified, and characterized as an enzyme catalyzing the hydrolysis of members of a class of signaling nucleotides, the dinucleoside polyphosphates, with its highest activity on adenosine 5'-tetraphospho-5'-adenosine (Ap4A), but also hydrolyzing Ap5A, Ap6A, Gp4G, and Gp5G. In each case, a pyrophosphate linkage is cleaved yielding a nucleoside triphosphate and the remaining nucleotide moiety.