3,148 research outputs found
Doubly Perfect Nonlinear Boolean Permutations
Due to implementation constraints the XOR operation is widely used in order
to combine plaintext and key bit-strings in secret-key block ciphers. This
choice directly induces the classical version of the differential attack by the
use of XOR-kind differences. While very natural, there are many alternatives to
the XOR. Each of them inducing a new form for its corresponding differential
attack (using the appropriate notion of difference) and therefore block-ciphers
need to use S-boxes that are resistant against these nonstandard differential
cryptanalysis. In this contribution we study the functions that offer the best
resistance against a differential attack based on a finite field
multiplication. We also show that in some particular cases, there are robust
permutations which offers the best resistant against both multiplication and
exponentiation base differential attacks. We call them doubly perfect nonlinear
permutations
THE ECONOMIC AND POLITICAL IMPLICATIONS OF DEEP DRAFT USER FEES
Public Economics,
On differential uniformity of maps that may hide an algebraic trapdoor
We investigate some differential properties for permutations in the affine
group, of a vector space V over the binary field, with respect to a new group
operation , inducing an alternative vector space structure on .Comment: arXiv admin note: text overlap with arXiv:1411.768
Features of spin-charge separation in the equilibrium conductance through finite rings
We calculate the conductance through rings with few sites described by
the model, threaded by a magnetic flux and weakly coupled to
conducting leads at two arbitrary sites. The model can describe a circular
array of quantum dots with large charging energy in comparison with the
nearest-neighbor hopping . We determine analytically the particular values
of for which a depression of the transmittance is expected as a
consequence of spin-charge separation. We show numerically that the equilibrium
conductance at zero temperature is depressed at those particular values of
for most systems, in particular at half filling, which might be easier
to realize experimentally.Comment: 8 pages, 7 figure
Increasing seasonal variation in the extent of rivers and lakes from 1984 to 2022
Knowledge of the spatial and temporal distribution of surface water is important for water resource management, flood risk assessment, monitoring ecosystem health, constraining estimates of biogeochemical cycles and understanding our climate. While global-scale spatiotemporal change detection of surface water has significantly improved in recent years due to planetary-scale remote sensing and computing, it has remained challenging to distinguish the changing characteristics of rivers and lakes. Here we analyze the spatial extent of permanent and seasonal rivers and lakes globally over the past 38 years based on new data of river system extents and surface water trends. Results show that while the total permanent surface area of both rivers and lakes has remained relatively constant, the areas with intermittent seasonal coverage have increased by 12 % and 27 % for rivers and lakes, respectively. The increase is statistically significant in over 84 % of global water catchments based on Spearman's rank correlations (rho) above 0.05 and p values less than 0.05. The seasonal river extent is nearly 32 % larger than the previously observed annual mean river extent, suggesting large seasonal variations that impact not only ecosystem health but also estimations of terrestrial biogeochemical cycles of carbon. The outcomes of our analysis are shared as the Surface Area of Rivers and Lakes (SARL) database, serving as a valuable resource for monitoring and research of hydrological cycles, ecosystem accounting, and water management.</p
On the generalized linear equivalence of functions over finite fields
In this paper we introduce the concept of generalized linear equivalence between functions defined over finite fields; this can be seen as an extension of the classical criterion of linear equivalence, and it is obtained by means of a particular geometric representation of the functions. After giving the basic definitions, we prove that the known equivalence relations can be seen as particular cases of the proposed generalized relationship and that there exist functions that are generally linearly equivalent but are not such in the classical theory. We also prove that the distributions of values in the Difference Distribution Table (DDT) and in the Linear Approximation Table (LAT) are invariants of the new transformation; this gives us the possibility to find some Almost Perfect Nonlinear (APN) functions that are not linearly equivalent (in the classical sense) to power functions, and to treat them accordingly to the new formulation of the equivalence criterion
Extension of nano-confined DNA: quantitative comparison between experiment and theory
The extension of DNA confined to nanochannels has been studied intensively
and in detail. Yet quantitative comparisons between experiments and model
calculations are difficult because most theoretical predictions involve
undetermined prefactors, and because the model parameters (contour length, Kuhn
length, effective width) are difficult to compute reliably, leading to
substantial uncertainties. Here we use a recent asymptotically exact theory for
the DNA extension in the "extended de Gennes regime" that allows us to compare
experimental results with theory. For this purpose we performed new
experiments, measuring the mean DNA extension and its standard deviation while
varying the channel geometry, dye intercalation ratio, and ionic buffer
strength. The experimental results agree very well with theory at high ionic
strengths, indicating that the model parameters are reliable. At low ionic
strengths the agreement is less good. We discuss possible reasons. Our approach
allows, in principle, to measure the Kuhn length and effective width of a
single DNA molecule and more generally of semiflexible polymers in solution.Comment: Revised version, 6 pages, 2 figures, 1 table, supplementary materia
Time trends in reported prevalence of kidney stones in the United States: 1976–199411.See Editorial by Goldfarb, p. 1951.
Time trends in reported prevalence of kidney stones in the United States: 1976–1994.BackgroundA body of evidence establishes that the occurrence of kidney stone disease has increased in some communities of industrialized countries. Information on recent temporal trends in the United States is lacking and population-based data on epidemiologic patterns are limited.Study objective was to determine whether kidney stone disease prevalence increased in the United States over a 20-year period and the influence of region, race/ethnicity, and gender on stone disease risk.MethodsWe measured the prevalence of kidney stone disease history from the United States National Health and Nutrition Examination Survey (II and III), population-based, cross-sectional studies, involving 15,364 adult United States residents in 1976 to 1980 and 16,115 adult United States residents in 1988 to 1994.ResultsDisease prevalence among 20- to 74-year-old United States residents was greater in 1988 to 1994 than in 1976 to 1980 (5.2% vs. 3.8%, P < 0.05), greater in males than females, and increased with age in each time period. Among 1988 to 1994 adults, non-Hispanic African Americans had reduced risk of disease compared to non-Hispanic Caucasians (1.7% vs. 5.9%, P < 0.05), and Mexican Americans (1.7% vs. 2.6%, P < 0.05). Also, age-adjusted prevalence was highest in the South (6.6%) and lowest in the West (3.3%). Findings were consistent across gender and multivariate adjusted odds ratios for stone disease history, including all demographic variables, as well as diuretic use, tea or coffee consumption, and dietary intake of calcium, protein, and fat did not materially change the results.ConclusionPrevalence of kidney stone disease history in the United States population increased between 1980 and 1994. A history of stone disease was strongly associated with race/ethnicity and region of residence
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