Obfuscation for Cryptographic Purposes

An obfuscation of a function F should satisfy two requirements: firstly, using it should be possible to evaluate F; secondly, should not reveal anything about F that cannot be learnt from oracle access to F. Several definitions for obfuscation exist. However, most of them are either too weak for or incompatible with cryptographic applications, or have been shown impossible to achieve, or both. We give a new definition of obfuscation and argue for its reasonability and usefulness. In particular, we show that it is strong enough for cryptographic applications, yet we show that it has the potential for interesting positive results. We illustrat

Mechanistic distinctions between agrin and laminin-1 induced aggregation of acetylcholine receptors

BACKGROUND: One of the earliest steps in synaptogenesis at the neuromuscular junction is the aggregation of nicotinic acetylcholine receptors at the postsynaptic membrane. This study presents quantitative analyses of receptor and α-Dystroglycan aggregation in response to agrin and laminin-1, alone or in combination. RESULTS: Both laminin and agrin increased overall expression of receptors on the plasma membrane. Following a 24 hour exposure, agrin increased the number of receptor aggregates but did not affect the number of α-Dystroglycan aggregates, while the reverse was true of laminin-1. Laminin also increased receptor concentration within aggregates, while agrin had no such effect. Finally, the spatial distribution of aggregates was indistinguishable from random in the case of laminin, while agrin induced aggregates were closer together than predicted by a random model. CONCLUSIONS: Agrin and laminin-1 both increase acetylcholine receptor aggregate size after 24 hours, but several lines of evidence indicate that this is achieved via different mechanisms. Agrin and laminin had different effects on the number and density of receptor and α-Dystroglycan aggregates. Moreover the random distribution of laminin induced (as opposed to agrin induced) receptor aggregates suggests that the former may influence aggregate size by simple mass action effects due to increased receptor expression

Bonded Cumomer Analysis of Human Melanoma Metabolism Monitored by 13C NMR Spectroscopy of Perfused Tumor Cells.

A network model for the determination of tumor metabolic fluxes from (13)C NMR kinetic isotopomer data has been developed and validated with perfused human DB-1 melanoma cells carrying the BRAF V600E mutation, which promotes oxidative metabolism. The model generated in the bonded cumomer formalism describes key pathways of tumor intermediary metabolism and yields dynamic curves for positional isotopic enrichment and spin-spin multiplets. Cells attached to microcarrier beads were perfused with 26 mm [1,6-(13)C2]glucose under normoxic conditions at 37 °C and monitored by (13)C NMR spectroscopy. Excellent agreement between model-predicted and experimentally measured values of the rates of oxygen and glucose consumption, lactate production, and glutamate pool size validated the model. ATP production by glycolytic and oxidative metabolism were compared under hyperglycemic normoxic conditions; 51% of the energy came from oxidative phosphorylation and 49% came from glycolysis. Even though the rate of glutamine uptake was ∼50% of the tricarboxylic acid cycle flux, the rate of ATP production from glutamine was essentially zero (no glutaminolysis). De novo fatty acid production was ∼6% of the tricarboxylic acid cycle flux. The oxidative pentose phosphate pathway flux was 3.6% of glycolysis, and three non-oxidative pentose phosphate pathway exchange fluxes were calculated. Mass spectrometry was then used to compare fluxes through various pathways under hyperglycemic (26 mm) and euglycemic (5 mm) conditions. Under euglycemic conditions glutamine uptake doubled, but ATP production from glutamine did not significantly change. A new parameter measuring the Warburg effect (the ratio of lactate production flux to pyruvate influx through the mitochondrial pyruvate carrier) was calculated to be 21, close to upper limit of oxidative metabolism

Surface-to-Bulk Redox Coupling through Thermally Driven Li Redistribution in Li- and Mn-Rich Layered Cathode Materials.

Li- and Mn-rich (LMR) layered cathode materials have demonstrated impressive capacity and specific energy density thanks to their intertwined redox centers including transition metal cations and oxygen anions. Although tremendous efforts have been devoted to the investigation of the electrochemically driven redox evolution in LMR cathode at ambient temperature, their behavior under a mildly elevated temperature (up to ∼100 °C), with or without electrochemical driving force, remains largely unexplored. Here we show a systematic study of the thermally driven surface-to-bulk redox coupling effect in charged Li1.2Ni0.15Co0.1Mn0.55O2. We for the first time observed a charge transfer between the bulk oxygen anions and the surface transition metal cations under ∼100 °C, which is attributed to the thermally driven redistribution of Li ions. This finding highlights the nonequilibrium state and dynamic nature of the LMR material at deeply delithiated state upon a mild temperature perturbation

Spirocyclic chromanes exhibit antiplasmodial activities and inhibit all intraerythrocytic life cycle stages

AbstractWe screened a collection of synthetic compounds consisting of natural-product-like substructural motifs to identify a spirocyclic chromane as a novel antiplasmodial pharmacophore using an unbiased cell-based assay. The most active spirocyclic compound UCF 201 exhibits a 50% effective concentration (EC50) of 350 nM against the chloroquine-resistant Dd2 strain and a selectivity over 50 using human liver HepG2 cells. Our analyses of physicochemical properties of UCF 201 showed that it is in compliance with Lipinski's parameters and has an acceptable physicochemical profile. We have performed a limited structure-activity-relationship study with commercially available chromanes preserving the spirocyclic motif. Our evaluation of stage specificities of UCF 201 indicated that the compound is early-acting in blocking parasite development at ring, trophozoite and schizont stages of development as well as merozoite invasion. SPC is an attractive lead candidate scaffold because of its ability to act on all stages of parasite's aexual life cycle unlike current antimalarials

Modeling, Identification, and Feedback Control of Noise in an Acoustic Duct

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/57830/1/AcousticDuctTCST1996.pd

Validity, Identification, and Distribution of the Roundscale Spearfish, Tetrapturus georgii (Teleostei: Istiophoridae): Morphological and Molecular Evidence

The roundscale spearfish, Tetrapturus georgii Lowe, 1840, is known only from four specimens from the Mediterranean and eastern North Atlantic. Additional specimens have not been identified since 1961, making the validity and distribution of this species unclear. Analysis of 16 billfish specimens from the western North Atlantic on the basis of scale morphology, anus position, and mitochondrial DNA confirms the validity of this species and extends its distribution. Mid-lateral scales are soft, notably rounded anteriorly, and bear 2–3 points distinct from those of the sympatric longbill spearfish (Tetrapturus pfluegeri Robins and de Sylva, 1963) and white marlin (Tetrapturus albidus Poey, 1860). Position of anus relative to first anal fin and a related morphometric ratio (distance from anus to first anal fin origin: height of first anal fin) are intermediate between T. pfluegeri and T. albidus. These characteristics match those described by Robins (1974) from the four eastern North Atlantic specimens of T. georgii. The mitochondrial ND4L, ND4, and cyt b gene sequences strongly support reciprocal monophyly of the western North Atlantic specimens relative to other Atlantic istiophorids. The difficulty in distinguishing between morphologically similar T. georgii and T. albidus in the field and the previously unrecognized presence of T. georgii in the western North Atlantic has implications for stock assessments of T. albidus, a species that is severely overfished

High-energy Behavior of the Double Photoionization of Helium from 2 to 12 keV

We report the ratio of double-to-single photoionization of He at several photon energies from 2 to 12 keV. By time-of-Aight methods, we find a ratio consistent with an asymptote at 1.5%±0.2%, essentially reached by h v≈4 keV. Fair agreement is obtained with older shake calculations of Byron and Joachain [Phys. Rev. 164, 1 (1967)], of Aberg [Phys. Rev. A 2, 1726 (1970)], and with recent many-body perturbation theory (MBPT) of Ishihara, Hino, and McGuire [Phys. Rev. A 44, 6980 (1991)]. The result lies below earlier MPBT calculations by Amusia et al. [J. Phys. B 8, 1248 (1975)] (2.3%), and well above semiempirical predictions of Samson [Phys. Rev. Lett. 65, 2861 (1990)], who expects no asymptote and predicts ơ(He2+)/ơ (He+) =0.3% at 12 keV