A Generalization of a Lower Bound Technique due to Fredman and Saks

{In a seminal paper of 1989, Fredman and Saks proved lower bounds for some important data-structure problems in the cell probe model. In particular, lower bounds were established on worst-case and amortized operation cost for the union-find problem and the prefix sum problem. The goal of this paper is to turn their proof technique into a general tool that can be applied to different problems and computational models. To this end we define two quantities: Output Variability depends only on the model of computation. It indicates how much variation can be found in the results of a program with certain resource bounds. This measures in some sense the power of a model. Problem Variability characterizes in a similar sense the difficulty of the problem. } Our Main Theorem shows that by comparing a model's output variability to a problem's problem variability, lower bounds on the complexity of solving the problem on the given model may be inferred. The theorem thus shows how to separate the analysis of the model of computation from that of the problem when proving lower bounds. We show how the results of Fredman and Saks fit our framework by computing the output variability of the cell probe model and the problem variability for problems considered in their paper. This allows us to reprove their lower bound results, and slightly extend them. The main purpose of this paper though is to present the generalized technique. Received January 25, 1999; revised July 30, 1999.     

Preparation of acidic or bifunctional catalysts by means of straightforward calcination of as-synthesized [Ga]-ZSM-5 zeolites obtained from alkali-free media. Propane aromatization

Propane aromatization (530°C, 1 atm) was used as a reaction model to evaluate the effect of the calcination temperature on the catalytic properties of an as-synthesized [Ga_1.3]-ZSM-5 zeolite obtained from alkali-free media and calcined at two different temperatures: 530°C (C-530) and 750°C (C-750). Results show that in spite of its lower acidity, C-750 is more active and selective toward aromatics than C-530. This is probably due to the fact that at higher temperature the decomposition of organic compounds used during the zeolite synthesis is accompanied by a partial degalliation of the zeolitic support leading to the production of a bifunctional xGa₂O₃ /H-[Ga_y-ZSM-5(2x+y=1.3)catalyst.     

Surface and deep and surface hardening of steel as a means of strengthening of critical machine parts and economy in material resources

"Tekhmash" Scientific and Production Union. Translated from Metallovedenie i Termicheskaya Obrabotka Metallov, No. 11, pp. 8–14, November, 1993.     

SLIM revisited

SLIM (spectroscopic localization by imaging), a tool for in vivo magnetic resonance spectroscopy that provides compartmental spectra from relatively few phase-encoded data, is limited by the inhomogeneities within each compartment. It is shown that the SLIM-derived spectra approach the average compartmental spectra as the number of phase encoded data approaches infinity, and the convergent rate of the error for each compartment is proportional to the size of the compartment. Numerical simulation studies are conducted to confirm the convergence property. A detailed discussion of the result is provided.     

Rheological factor in the thermal problem of SHF-hyperthermia-treatment. 2. Simulation of relative blood flow variation

The rheological effect on the temperature field in a homogeneous tissue under SHF hyperthermia treatment is discussed.Academic Scientific Complex The A. V. Luikov Heat and Mass Transfer Institute, Academy of Sciences of Belarus, Minsk. Translated from Inzhenerno-Fizicheskii Zhurnal, Vol. 65, No. 5, pp. 561–566, November, 1993.     

Isolation of penicillin-resistant Streptococcus pneumoniae in Saga Medical School Hospital

A recent nationwide increase in beta-lactams-resistant Streptococcus pneumoniae has attracted a great deal of attention. We studied the drug sensitivity of S. pneumoniae isolated from various clinical specimens in Saga Medical School Hospital between April 1988 and December 1991. To determine the drug sensitivity of the strains, we used a micro-dilution method and determined the MIC. Drug resistance was evaluated using MIC of ampicillin (ABPC) as a reference MIC, and the results were roughly classified into the following three groups: sensitive (< or = 0.1 microgram/ml), moderately resistant (0.2-3.13 micrograms/ml) and highly resistant (> or = 6.25 micrograms/ml). The isolation frequency was calculated on the basis of one strain from one patient. No strain of S. pneumoniae with high resistance against ABPC was found in 1988 (94 strains of S. pneumoniae were isolated) and 1990 (115 strains isolated), but one such strain (0.8%) was found among 129 strains isolated in 1989, and 2 such strains (2.4%) among 84 strains isolated in 1991. Moderately resistant strains were isolated at the frequencies of 12.8%, 15.5%, 22.6%, and 21.4% respectively, in 1988, 1989, 1990, and 1991. A sum of the frequencies of "moderately resistant" and "highly resistant" (2.4%) strains was 23.8% in 1991. The frequency of resistant strains is increasing and the intensity of resistance is also being elevated.     

Initial experience with the fish-shaped incision in mastectomy

The authors are showing their early experiences with the modified mastectomy with the use of the fish-shape incision, first published by Nowacki and Towpik in 1988. The fish-shaped incision reduces the amount of the skin in the axilla by adding two triangles on the lateral edge of the incision, prevents the "dog ear" deformity and makes the clearance of the axilla easier.     

Activation effect of halides on chromium electrodeposition from chromic acid baths

The current efficiency of chromium electrodeposition and cathodic polarization curves were determined in halide-chromic acid-sulphuric acid systems. The composition of the cathodic films formed was determined by XPS and AES. The results show that sulphate is an effective catalyst for the deposition of bright chromium and that the current efficiency of the chromium deposition increases remarkably when F^– and Cl^– are added to the bath, and also that F^– and Cl^– participate in the formation of the films. The depth profile curves of the film show that halide is distributed in the inner layer of the film, and SO₄ ^2– in the surface layer. It is deduced that F^– and Cl^– form a bridged complex, [C^III-X^–-Cr^III], in which electron transition is easily carried out.     

Principle of selection and mechanism of action of polymer additives in modification of polyacrylonitrile fiber

Based on theoretical and experimental data, a correlation was demonstrated between the stability factor of concentrated solutions, difference in the glass transition temperatures of the components of the mixtures, and reaction parameter between polymers. It was found that the polymer reaction parameter can be used as the criterion for selecting the optimum concentration of the second component in fabrication of fibers from polymer blends. The doping role of small amounts of polymer additives in PAN, which causes an extreme increase in the physicomechanical and especially the fatigue properties of fibers from polymer blends, was demonstrated.Translated from Khimicheskie Volokna, No. 4, pp. 12–14, July–August, 1992.     

AI-12.5 wt % Si ribbons prepared by melt spinning

Aluminium-silicon alloy with composition 12.5 wt% Si was rapidly quenched from the melt at a cooling rate of about 10⁶ Ks^–1 using the melt-spinning technique. The resulting ribbons were investigated by resistivity measurements and X-ray diffraction. The resistivity of the 20 m thick ribbons was 26.6 cm. This is 4.4 times its bulk resistivity value. The activation energy calculated from isothermal ageing was 1.14 ± 0.1 eV. The limit of primary solid solubility is extended almost to the eutectic composition and the large supersaturation is relieved by thermal annealing.