An Empirical Study of the Usage of Checksums for Web Downloads

Checksums, typically provided on webpages and generated from cryptographic hash functions (e.g., MD5, SHA256) or signature schemes (e.g., PGP), are commonly used on websites to enable users to verify that the files they download have not been tampered with when stored on possibly untrusted servers. In this paper, we shed light on the current practices regarding the usage of checksums for web downloads (hash functions used, visibility and validity of checksums, type of websites and files, presence of instructions, etc.), as this has been mostly overlooked so far. Using a snowball-sampling strategy for the 200,000 most popular domains of the Web, we first crawled a dataset of 8.5M webpages, from which we built, through an active-learning approach, a unique dataset of 277 diverse webpages that contain checksums. Our analysis of these webpages reveals interesting findings about the usage of checksums. For instance, it shows that checksums are used mostly to verify program files, that weak hash functions are frequently used and that a non-negligible proportion of the checksums provided on webpages do not match that of their associated files. We make freely available our dataset and the code for collecting and analyzing it. Finally, we complement our analysis with a survey of the webmasters of the considered webpages (26 complete responses), shedding light on the reasons behind the checksum-related choices they make

Triggering, guiding and deviation of long air spark discharges with femtosecond laser filament

International audienceIn the perspective of the laser lightning rod, the ability of femtosecond filaments to trigger and to guide large scale discharges has been studied for several years. The present paper reports recent experimental results showing for the first time that filaments are able not only to trigger and guide but also to divert an electric discharge from its normal path. Laser filaments are also able to divert the spark without contact between laser and electrodes at large distance from the laser. A comparison between negative and positive discharge polarities also reveals important discrepancies in the guiding mechanism

Temperature measurement of sub-micrometric ICs by scanning thermal microscopy

Surface temperature measurements were performed with a Scanning Thermal Microscope mounted with a thermoresistive wire probe of micrometrSurface temperature measurements were performed with a Scanning Thermal Microscope mounted with a thermoresistive wire probe of micrometric size. A CMOS device was designed with arrays of resistive lines 0.35µm in width. The array periods are 0.8 µm and 10µm to study the spatial resolution of the SThM. Integrated Circuits with passivation layers of micrometric and nanometric thicknesses were tested. To enhance signal-to-noise ratio, the resistive lines were heated with an AC current. The passivation layer of nanometric thickness allows us to distinguish the lines when the array period is 10μm. The results raise the difficulties of the SThM measurement due to the design and the topography of ICs on one hand and the size of the thermal probe on the other hand.ic size. A CMOS device was designed with arrays of resistive lines 0.35µm in width. The array periods are 0.8 µm and 10µm to study the spatial resolution of the SThM. Integrated Circuits with passivation layers of micrometric and nanometric thicknesses were tested. To enhance signal-to-noise ratio, the resistive lines were heated with an AC current. The passivation layer of nanometric thickness allows us to distinguish the lines when the array period is 10μm. The results raise the difficulties of the SThM measurement due to the design and the topography of ICs on one hand and the size of the thermal probe on the other hand

Cobalamin deficiency resulting in a rare haematological disorder: a case report

INTRODUCTION: We present the case of a patient with a cobalamin deficiency resulting in pancytopaenia, emphasizing the importance to define, diagnose and treat cobalamin deficiency. CASE PRESENTATION: A 52-year-old man from the Democratic Republic of Congo presented to the emergency department with shortness of breath and a sore tongue. Physical examination was unremarkable. His haemoglobin was low and the peripheral blood smear revealed pancytopaenia with a thrombotic microangiopathy. The findings were low cobalamin and folate levels, and high homocysteine and methylmalonate levels. Pernicious anaemia with chronic atrophic gastritis was confirmed by gastric biopsy and positive antiparietal cell and anti-intrinsic factor antibodies. Cobalamin with added folate was given. Six months later, the patient was asymptomatic. CONCLUSION: Cobalamin deficiency should always be ruled out in a patient with pancytopaenia. Our case report highlights a life-threatening cobalamin deficiency completely reversible after treatment

Plant-dominated assemblage and invertebrates from the lower Cenomanian of Jaunay-Clan, western France

International audienceTwo fossil localities are reported on the "LGV SEA" railroad from the Lower Cenomanianof Jaunay-Clan (JC), near Poitiers, western France. The laminated mudstones yielded plantfossils including ferns (Cladophlebis, Osmundophyllum, Ruffordia goeppertii, Sphenopteris),conifers (Brachyphyllum, Dammarophyllum, Pagiophyllum), and terrestrial and aquaticfreshwater angiosperms (Eucalyptolaurus depreii, Ploufolia). They are associated with acoleopteran insect that shows systematic affinities to the modern subfamily Chrysomeli-nae (Chrysomelidae). This assemblage suggests connections with arborescent vegetationgrowing in calm freshwater environment. Brackish to marine invertebrates also occurand include a dakoticancroid crab (Brachyura, Podotremata, Dakoticancroidea) and a fewbivalves (Brachidontes). They suggest brackish episodes during pond sedimentation in acoastal environment. Lastly, vertebrates are represented by an isolated feather

K+ channel openers restore verapamil-inhibited lung fluid resolution and transepithelial ion transport

<p>Abstract</p> <p>Background</p> <p>Lung epithelial Na⁺channels (ENaC) are regulated by cell Ca²⁺signal, which may contribute to calcium antagonist-induced noncardiogenic lung edema. Although K⁺channel modulators regulate ENaC activity in normal lungs, the therapeutical relevance and the underlying mechanisms have not been completely explored. We hypothesized that K⁺channel openers may restore calcium channel blocker-inhibited alveolar fluid clearance (AFC) by up-regulating both apical and basolateral ion transport.</p> <p>Methods</p> <p>Verapamil-induced depression of heterologously expressed human αβγ ENaC in <it>Xenopus </it>oocytes, apical and basolateral ion transport in monolayers of human lung epithelial cells (H441), and <it>in vivo </it>alveolar fluid clearance were measured, respectively, using the two-electrode voltage clamp, Ussing chamber, and BSA protein assays. Ca²⁺signal in H441 cells was analyzed using Fluo 4AM.</p> <p>Results</p> <p>The rate of <it>in vivo </it>AFC was reduced significantly (40.6 ± 6.3% of control, <it>P </it>< 0.05, n = 12) in mice intratracheally administrated verapamil. K_Ca3.1(1-EBIO) and K_ATP(minoxidil) channel openers significantly recovered AFC. In addition to short-circuit current (Isc) in intact H441 monolayers, both apical and basolateral Isc levels were reduced by verapamil in permeabilized monolayers. Moreover, verapamil significantly altered Ca²⁺signal evoked by ionomycin in H441 cells. Depletion of cytosolic Ca²⁺in αβγ ENaC-expressing oocytes completely abolished verapamil-induced inhibition. Intriguingly, K_V(pyrithione-Na), K _Ca3.1(1-EBIO), and K_ATP(minoxidil) channel openers almost completely restored the verapamil-induced decrease in Isc levels by diversely up-regulating apical and basolateral Na⁺and K⁺transport pathways.</p> <p>Conclusions</p> <p>Our observations demonstrate that K⁺channel openers are capable of rescuing reduced vectorial Na⁺transport across lung epithelial cells with impaired Ca²⁺signal.</p

A comprehensive fracture prevention strategy in older adults: The European union geriatric medicine society (EUGMS) statement

Prevention of fragility fractures in older people has become a public health priority, although the most appropriate and cost-effective strategy remains unclear. In the present statement, the Interest group on falls and fracture prevention of the European union geriatric medicine society (EUGMS), in collaboration with the International association of gerontology and geriatrics for the European region (IAGG-ER), the European union of medical specialists (EUMS), the Fragility fracture network (FFN), the International osteoporosis foundation (IOF) – European society for clinical and economic aspects of osteoporosis and osteoarthritis (ECCEO), outlines its views on the main points in the current debate in relation to the primary and secondary prevention of falls, the diagnosis and treatment of bone fragility, and the place of combined falls and fracture liaison services for fracture prevention in older people