scholarly journals Significantly Improved Multi-bit Differentials for Reduced Round Salsa and ChaCha

2017 ◽  
pp. 261-287 ◽  
Author(s):  
Arka Rai Choudhuri ◽  
Subhamoy Maitra
Keyword(s):  
Main Idea ◽  
Stream Ciphers ◽  
Exhaustive Search ◽  
Linear Combinations ◽  
Linear Approximations ◽  
Linear Attack ◽  
First Time ◽  
Very High

ChaCha and Salsa are two software oriented stream ciphers that have attracted serious attention in academic as well as commercial domain. The most important cryptanalysis of reduced versions of these ciphers was presented by Aumasson et al. in FSE 2008. One part of their attack was to apply input difference(s) to investigate biases after a few rounds. So far there have been certain kind of limited exhaustive searches to obtain such biases. For the first time, in this paper, we show how to theoretically choose the combinations of the output bits to obtain significantly improved biases. The main idea here is to consider the multi-bit differentials as extension of suitable single-bit differentials with linear approximations, which is essentially a differential-linear attack. As we consider combinations of many output bits (for example 19 for Salsa and 21 for ChaCha), exhaustive search is not possible here. By this method we obtain very high biases for linear combinations of bits in Salsa after 6 rounds and in ChaCha after 5 rounds. These are clearly two rounds of improvement for both the ciphers over the existing works. Using these biases we obtain several significantly improved cryptanalytic results for reduced round Salsa and ChaCha that could not b obtained earlier. In fact, with our results it is now possible to cryptanalyse 6-round Salsa and 5-round ChaCha in practical time.

scholarly journals Shell-crossing in a ΛCDM Universe

2020 ◽  
Vol 501 (1) ◽  
pp. L71-L75
Author(s):  
Cornelius Rampf ◽  
Oliver Hahn
Keyword(s):  
Dark Matter ◽  
Perturbation Theory ◽  
Large Scale ◽  
Cold Dark Matter ◽  
Three Dimensional ◽  
Random Initial Data ◽  
Recursion Relations ◽  
Indispensable Tool ◽  
First Time ◽  
Very High

ABSTRACT Perturbation theory is an indispensable tool for studying the cosmic large-scale structure, and establishing its limits is therefore of utmost importance. One crucial limitation of perturbation theory is shell-crossing, which is the instance when cold-dark-matter trajectories intersect for the first time. We investigate Lagrangian perturbation theory (LPT) at very high orders in the vicinity of the first shell-crossing for random initial data in a realistic three-dimensional Universe. For this, we have numerically implemented the all-order recursion relations for the matter trajectories, from which the convergence of the LPT series at shell-crossing is established. Convergence studies performed at large orders reveal the nature of the convergence-limiting singularities. These singularities are not the well-known density singularities at shell-crossing but occur at later times when LPT already ceased to provide physically meaningful results.

General method for cloning Neurospora crassa nuclear genes by complementation of mutants

1985 ◽  
Vol 5 (9) ◽  
pp. 2272-2278
Author(s):  
R A Akins ◽  
A M Lambowitz
Keyword(s):  
Neurospora Crassa ◽  
Genomic Library ◽  
Selection Procedure ◽  
Nuclear Genes ◽  
Shuttle Vectors ◽  
Sib Selection ◽  
First Time ◽  
Very High ◽  
Restriction Site Polymorphisms ◽  
General Method

We have developed a sib selection procedure for cloning Neurospora crassa nuclear genes by complementation of mutants. This procedure takes advantage of a modified N. crassa transformation procedure that gives as many as 10,000 to 50,000 stable transformants per microgram of DNA with recombinant plasmids containing the N. crassa qa-2+ gene. Here, we describe the use of the sib selection procedure to clone genes corresponding to auxotrophic mutants, nic-1 and inl. The identities of the putative clones were confirmed by mapping their chromosomal locations in standard genetic crosses and using restriction site polymorphisms as genetic markers. Because we can obtain very high N. crassa transformation frequencies, cloning can be accomplished with as few as five subdivisions of an N. crassa genomic library. The sib selection procedure should, for the first time, permit the cloning of any gene corresponding to an N. crassa mutant for which an appropriate selection can be devised. Analogous procedures may be applicable to other filamentous fungi before the development of operational shuttle vectors.

scholarly journals Visible AO Observations at Halpha for Accreting Young Planets

2013 ◽  
Vol 8 (S299) ◽  
pp. 32-33
Author(s):  
L.M. Close ◽  
K. Follette ◽  
J.R. Males ◽  
K. Morzinski ◽  
T.J. Rodigas ◽  
...  
Keyword(s):  
Adaptive Optics ◽  
Binary Stars ◽  
Optical Resolution ◽  
Ccd Camera ◽  
Short Exposure ◽  
Low Mass ◽  
Orion Trapezium ◽  
First Time ◽  
Adaptive Optics System ◽  
Very High

AbstractWe utilized the new high-order (250-378 mode) Magellan Adaptive Optics system (MagAO) to obtain very high-resolution science in the visible with MagAO's VisAO CCD camera. In the good-median seeing conditions of Magellan (0.5–0.7″) we find MagAO delivers individual short exposure images as good as 19 mas optical resolution. Due to telescope vibrations, long exposure (60s) r' (0.63μm) images are slightly coarser at FWHM = 23-29 mas (Strehl ~ 28%) with bright (R < 9 mag) guide stars. These are the highest resolution filled-aperture images published to date. Images of the young (~ 1 Myr) Orion Trapezium θ1 Ori A, B, and C cluster members were obtained with VisAO. In particular, the 32 mas binary θ1 Ori C1C2 was easily resolved in non-interferometric images for the first time. Relative positions of the bright trapezium binary stars were measured with ~ 0.6–5 mas accuracy. In the second commissioning run we were able to correct 378 modes and achieved good contrasts (Strehl>20% on young transition disks at Hα). We discuss the contrasts achieved at Hα and the possibility of detecting low mass (~ 1–5 Mjup) planets (past 5AU) with our new SAPPHIRES survey with MagAO at Hα.

scholarly journals Gold in Irish Coal: Palaeo-Concentration from Metalliferous Groundwaters

Minerals ◽  
2020 ◽  
Vol 10 (7) ◽  
pp. 635
Author(s):  
Liam A. Bullock ◽  
John Parnell ◽  
Joseph G.T. Armstrong ◽  
Magali Perez ◽  
Sam Spinks
Keyword(s):  
Heat Flow ◽  
Low Temperature ◽  
Precious Metals ◽  
High Heat ◽  
Selenium Content ◽  
Foreland Basins ◽  
High Heat Flow ◽  
South Wales ◽  
First Time ◽  
Very High

Gold grains, up to 40 μm in size and containing variable percentages of admixed platinum, have been identified in coals from the Leinster Coalfield, Castlecomer, SE Ireland, for the first time. Gold mineralisation occurs in sideritic nodules in coals and in association with pyrite and anomalous selenium content. Mineralisation here may have reflected very high heat flow in foreland basins north of the emerging Variscan orogenic front, responsible for gold occurrence in the South Wales Coalfield. At Castlecomer, gold (–platinum) is attributed to precipitation with replacive pyrite and selenium from groundwaters at redox interfaces, such as siderite nodules. Pyrite in the cores of the nodules indicates fluid ingress. The underlying Caledonian basement bedrock is mineralised by gold, and thus likely provided a source for gold. The combination of the gold occurrences in coal in Castlecomer and in South Wales, proximal to the Variscan orogenic front, suggests that these coals along the front could comprise an exploration target for low-temperature concentrations of precious metals.

scholarly journals First evaluation of coral recruitment in Madagascar

2021 ◽  
Vol 20 (1) ◽  
pp. 47-62
Author(s):  
Gildas G.B. Todinanahary ◽  
Nomeniarivelo Hasintantely ◽  
Igor Eeckhaut ◽  
Thierry Lavitra
Keyword(s):  
Larval Density ◽  
Average Density ◽  
Recruitment Rate ◽  
Seasonal Distribution ◽  
Coral Recruitment ◽  
Significant Difference ◽  
Southwest Region ◽  
The Mean ◽  
First Time ◽  
Very High

The distribution of larvae and recruitment of scleractinians in the southwest region of Madagascar were evaluated for the first time between October 2013 and September 2014 at 3 sites. The presence of coral larvae (planulae) was monitored through weekly sampling using a plankton net and the recruitment rate evaluated by monthly sampling of the newly settled corals (<1 year stage) on recruitment tiles and by a monitoring of the recruitment of juveniles (1< Juveniles < 2 years) using the quadrat method. Planulae were present in the plankton for 9 months during the survey. The recorded mean annual density of planula varied from 0.43 ± 0.41 larvae m-3 to 3.23 ± 5.72 larvae m-3 depending on site, with a peak in larval density towards the end of November and the beginning of December. The variability in the occurrence of planula is very high and implied that the density observed in the year does not present a significant difference between the sites (pKW=0.33). The average density of total recruits was 620.13 ± 621.30 recruits m-2, 40.28 ± 50.97 recruits m-2 and 36.34 ± 33.82 recruits m-2, respectively at the sites of Nosy Tafara, Grande Vasque and Rose Garden. Seasonal distribution of coral recruitment was different between the sites. The mean annual density of newly settled recruits (< 1 month stage) was significantly higher at Nosy Tafara with 94.91±101.08 recruits m-2 compared to Grande Vasque and Rose Garden with 18.75±34.32 recruits m-2 and 11.57±18.47 recruits m-2 (pKW<0.001), respectively. The highest density of newly settled recruits was observed between October to December. Higher density of recruits was also observed in March at Nosy Tafara and in May at all three sites. Results of juvenile monitoring showed high rates (> 10 juveniles m-2) compared to other regions and the threshold, but it revealed high mortality among recruits. Coral recruitment in the southwest region of Madagascar was found to be high and could result in increased resilience of the coral reef assemblages.

scholarly journals Clippers (Chronic Lymphocytic Inflammation with Pontine Perivascular Enhancement Responsive to Steroids) Management Experience at a single Third-level Medical Center in México.

2021 ◽  
Vol 8 (2) ◽  
pp. 01-07
Author(s):  
Brenda Bertado Cortes ◽  
Brian Madariaga Cortes ◽  
Massiel Zenteno Zenteno ◽  
Bayron Alexander Sandoval Bonilla
Keyword(s):  
Stereotactic Biopsy ◽  
Medical Center ◽  
Medical Personnel ◽  
The Central Nervous System ◽  
Management Experience ◽  
Magnetic Resonance Imaging Mri ◽  
Salt And Pepper ◽  
First Contact ◽  
First Time ◽  
Very High

Chronyc lymphosytic inflammation with pontine perivascular enhacement responsive to steroids (CLIPPERS), described for the first time in 2010 by Pittock and collaborators, is a rare inflammatory disease of the central nervous system (SNC) characterized by the presence of punctuate or curvilinear lesions described like “salt and pepper” appearance on the magnetic resonance imaging (MRI), that enhance with Gadoliniumn administration; this lesions show an exquisite response to corticosteroid therapy. The etiology of this disease remains unknown. However, the existing articles suggest an autoimmune component, which may or may not be related to other autoinmmune, infectious or malignant pathologies. Due to the above, it is generally considered that in order to reach the diagnosis of CLIPPERS, the possibility of other more common or aggressive pathologies must first be ruled out through extensive investigation. However, if the clinical and imaging presentation are typical and there is a very high suspicion of CLIPPERS, early initiation of glucosteroid therapy may be recommended. There is no unanimous therapy plan due to the few cases reported worldwide thus far. In cases of severe relapses or atypical behavior, both clinical and radiological, it is recommended to consider a stereotactic biopsy of the lesion to integrate the definitive diagnosis. Because it is a rare disease, it is relatively unknown to first- contact medical personnel; in our particular case, this leads to referral to the neurosurgery department who, thanks to their experience, have considered a demilinizing disease as a diagnostic possibility and requested an assessment by the neurology department. Here, we report the evolution and management of three diagnosed cases of CLIPPERS at a single Third-level Medical Center in México; based on clinical, radiological and neuropathological findings; as well as highlighting the importance of lesion biopsy in selected cases.

A method of hidden messages embedding in graphlike structures of a social network

2018 ◽  
Author(s):  
И.В. Нечта
Keyword(s):  
Social Networks ◽  
Social Network ◽  
Main Idea ◽  
The Other ◽  
Secret Message ◽  
Automatic Registration ◽  
Connected Component ◽  
Single Node ◽  
Empty Container ◽  
First Time

Предложен новый метод передачи скрытых сообщений в социальных сетях на примере сети “Вконтакте”, позволяющий через структуру графа друзей пользователя внедрять секретные сообщения. Получены количественные оценки объема внедряемого сообщения в графы различного размера. Показана необходимость добавления избыточности во внедряемое сообщение. Представленный метод позволяет использовать другие графоподобные структуры социальной сети для внедрения скрытых сообщений. Purpose. This article addresses the construction of a new method for transmission of hidden messages in social networks. Methodology. The research employs methods of information theory, probability theory and mathematical statistics The Shannon entropy is used as the statistics for the analysis of an embedded message. Findings. The author proposed using the graphical structures of social networks as a container for the secret message transmission for the first time. As an example, the popular Vkontakte network is considered. The main idea of the method involves using the structure of the user’s friends graph to embed a secret message. Based on the available vertices (friends’ accounts), a complete graph is constructed, and its edges are enumerated. Each edge of the graph corresponds to one bit of the message being embedded: the bit is “1”, if the edge is present in the graph (one account in friends of the other), the bit is “0” if the edge is missing. To transfer the graph from one person to another, a key vertex is used. The specified vertex is connected by an edge with each connected component of the graph, which allows the graph to be transmitted using a single node and take into account all the vertices (including isolated ones). When retrieving a message, the key vertex and the edges connected to it are not considered. Conclusions. During the experimental research, it was shown that messages extracted from an empty container differ from the encrypted message by the probability distribution of bits. The necessity of adding redundancy to transmitted secret messages is shown with the purpose of “leveling” the statistical properties of an empty and filled container. The results of the experiment have showed that this method of steganography allows embedding a large amount of information into various social network structures represented in the form of a graph. It was noted in the paper that potentially “narrow” place of the algorithm is registration of new accounts. The restrictions imposed by the administration of some social networks for security purposes do not always allow automatic registration of new accounts, which makes the process of message embedding more difficult.

scholarly journals Methyl Salicylate Glycosides in Some Italian Varietal Wines

Molecules ◽  
2019 ◽  
Vol 24 (18) ◽  
pp. 3260 ◽  
Author(s):  
Carlin ◽  
Masuero ◽  
Guella ◽  
Vrhovsek ◽  
Mattivi
Keyword(s):  
Methyl Salicylate ◽  
Total Concentration ◽  
Plant Secondary Metabolites ◽  
Point Of View ◽  
1H And 13C Nmr ◽  
Vitis Riparia ◽  
13C Nmr Analysis ◽  
First Time ◽  
Gaultheria Procumbens ◽  
Very High

Glycosides are ubiquitous plant secondary metabolites consisting of a non-sugar component called an aglycone, attached to one or more sugars. One of the most interesting aglycones in grapes and wine is methyl salicylate (MeSA), an organic ester naturally produced by many plants, particularly wintergreens. To date, nine different MeSA glycosides from plants have been reported, mainly spread over the genera Gaultheria, Camellia, Polygala, Filipendula, and Passiflora. From a sensorial point of view, MeSA has a balsamic-sweet odor, known as Wintergreen. MeSA was found in Vitis riparia grapes, in Vitis vinifera sp. and in the Frontenac interspecific hybrid. We found that the MeSA glycosides content in Verdicchio wines and in some genetically related varieties (Trebbiano di Soave and Trebbiano di Lugana) was very high. In order to understand which glycosides were present in wine, the methanolic extract of Verdicchio wine was injected into a UPLC-Q-TOF-HDMS and compared to the extracts of different plants rich in such glycosides. Using pure standards, we confirmed the existence of two glycosides in wine: MeSA 2-O--d-glucoside and MeSA 2-O--d-xylopyranosyl (1-6) -d-glucopyranoside (gaultherin). For the first time, we also tentatively identified other diglycosides in wine: MeSA 2-O--l-arabinopyranosyl (1-6)--d-glucopyranoside (violutoside) and MeSA 2-O--d-apiofuranosyl (1-6)--d-glucopyranoside (canthoside A), MeSA 2-O--d-glucopyranosyl (1-6)-O--d-glucopyranoside (gentiobioside) and MeSA 2-O--l-rhamnopyranosyl (1-6)--d-glucopyranoside (rutinoside). Some of these glycosides have been isolated from Gaultheria procumbens leaves by preparative liquid chromatography and structurally annotated by 1H- and 13C-NMR analysis. Two of the peaks isolated from Gaultheria procumbens leaves, namely MeSA sambubioside and MeSA sophoroside, were herein observed for the first time. Six MeSA glycosides were quantified in 64 Italian white wines, highlighting the peculiar content and pattern in Verdicchio wines and related cultivars. The total concentration in bound and free MeSA in Verdicchio wines varied in the range of 456–9796 g/L and 5.5–143 g/L, respectively, while in the other wines the bound and free MeSA was below 363 g/L and 12 g/L, respectively. As this compound’s olfactory threshold is between 50 and 100 g/L, our data support the hypothesis that methyl salicylate can contribute to the balsamic scent, especially in old Verdicchio wines.

scholarly journals Entry and Exit of Nonprofit Organizations

2018 ◽  
Vol 9 (2) ◽  
Author(s):  
Gian Paolo Barbetta ◽  
Paolo Canino ◽  
Stefano Cima ◽  
Flavio Verrecchia
Keyword(s):  
Panel Data ◽  
Nonprofit Organizations ◽  
Census Data ◽  
Nonprofit Sector ◽  
Entry And Exit ◽  
Entry Rate ◽  
Firm Level ◽  
Significant Development ◽  
First Time ◽  
Very High

AbstractThe latest census of Italian nonprofit organizations – compared with the previous one – showed a significant development of the nonprofit sector between 2001 and 2011. The number of organizations increased more than 28 % while the growth of employees (about 61 %) was even more impressive.These results notwithstanding, the mere comparison of aggregate census data does not give a true understanding of the dynamic of the sector. The entry and exit of organizations, as well as their migration between different sectors of activity, or geographical areas, can be analyzed properly only using firm-level panel data, but these data are rarely available so that only a few authors had a chance to use them. In this paper, we try to fill this gap using firm-level panel data for the first time in Italy. Our analysis tempers the optimism arising from aggregate data. We show that: a) part of the growth is determined by the emergence of already active organizations that were not detected a decade ago; b) because of low barriers, the entry of new nonprofit organizations is very relevant, but their net contribution to the growth of employment is quite small; c) opposite to what happened in other countries, the exit of nonprofit organizations is very significant, and d) organizations that were already active a decade ago gave the most important contribution to the growth of employment. We also investigate geographical trends, showing that the slower growth of the nonprofit sector in Southern Italy depends on the very high exit rate of the area, while the entry rate is more or less in line with the rest of the country.

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