308 research outputs found

    A Comparative Study Between RIPEMD160 and SHA256 Hash Functions On Digital Holy Quran Integrity Verification

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    In Data Security and Cryptography areas, hash functions play a fundamental and important role in the field of Integrity, This paper presents a performance evaluation of two cryptographic hash functions SHA256 and RIPEMD160 which used to verify the integrity of digital holy Quran and determine which one is better. SHA256 and RIPEMD160 hash functions have been selected in this comparison because their characteristics speed and space characteristics, both hash functions have their own advantages and disadvantages what distinguishes them from others, which will be discuss in detail in Background section. This study focuses on security and performance analysis. Security analysis where many experiments be applied to find out the strength and effectiveness of each two hash functions and hash collisions be analysed. The performance analysis will be applied by measuring the speed of the proposed methods in this study. The results show that the RIPEMD160 hash function is faster than SHA256 hash function for the integrity verification on a digital copy of the Holy Quran. &nbsp

    Three Hash Functions Comparison on Digital Holy Quran Integrity Verification

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    This paper provides a study of hash functions comparison on holy Quran integrity verification to ensure integrity of data in digital copy of holy Quran. There are many methods available in data security area for integrity verification. This study presents a comparison of three cryptographic hash functions SHA256, RIPEMD160 and Blake3 which used to verify the integrity of digital holy Quran and determine which one is better. Blake3 hash function is chosen in this proposed schema because it has many characteristics, the most important of which is the speed characteristic, and it will be mentioned in detail in Background section. Furthermore security analysis and performance analysis are focused on this study. In security analysis by apply four experiments to find out the strength and effectiveness of each three hash functions and all possible possibilities of hash collisions be carefully analysed and studied. Speed in term of execution time is measuring for all three hash function and this is under the umbrella of the performance analysis. The results that we have obtained say that the Blake3 hash function is the fastest function with the rest two hash functions. And the resulting number of the time that the attacker need to come up with a fake verse using SHA256/BLAKE3 will be greater than the number obtained by using RIPEMD160. &nbsp

    Visual distraction in cytopathology: should we be concerned?

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    Visual distraction in cytopathology has not been previously investigated as a source of diagnostic error, presumably because the viewing field of a conventional light microscope is considered large enough to minimise interference from peripheral visual stimuli. Virtual microscopy, which involves the examination of digitised images of pathology specimens on computer screens, is beginning to challenge the central role of light microscopy as a diagnostic tool in cytopathology. The relatively narrow visual angle offered by virtual microscopy makes it conceivable that users of these systems are more vulnerable to visual interference. Using a variant of a visual distraction paradigm (the Eriksen flanker task), the aim of the study was to determine whether the accuracy and speed of interpreting cells on a central target screen is affected by images of cells and text displayed on neighbouring monitors under realistic reading room conditions

    Interpregnancy interval and the risk of preterm birth: a case-control study of infants born at Al-sadaqa general teaching hospital, Aden, Yemen

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    Background: Interpregnancy interval (IPI) is a known risk factor for preterm birth. The aim of this study was to assess the relationship between IPI and spontaneous preterm birth, and to identify the influence of confounding variables such as socioeconomic status, maternal age, and reproductive history.Methods: This is a hospital-based, case-control study conducted in the department of neonatology, Al-Sadaqa General Teaching Hospital, Aden, during June to September 2011. A case was defined as infant born spontaneously before 37 weeks of gestation and control was a next eligible infant born between 37-42 complete weeks of gestation. Comparison between groups was assessed by statistical analysis and odds ratio were calculated for confounding factors.Results: A total of 100 preterm (cases) and 100 full-term (controls) infants were evaluated for the effects of IPI. Intervals of both <12 months and 12-˂24 months were significantly associated with preterm births compared to control (37% vs 12% and 73% vs 46% respectively, all p<0.05). The risk of preterm birth was higher in association with low number of antenatal care visits (OR=10, 95% CI=1.62-61.46, p=0.018), younger women’s age (OR=8, 95% CI= 1.35-8.4, p=0.001), non-educated mother (OR=7.92, 95% CI=2.49-25.22, p=0.002) and gravid 2-3 (OR=6.5, 95% CI= 5.06-53.8, p=0.001). Significant risk was also observed among mother with low socio-economic status and residents of rural areas (all p<0.05).Conclusions: Short IPI is significant risk factors for preterm birth. This highlights the importance of counseling women in childbearing age to wait at least 24 months between delivery and subsequent conception

    Visual Search Elicits the Electrophysiological Marker of Visual Working Memory

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    Background: Although limited in capacity, visual working memory (VWM) plays an important role in many aspects of visually-guided behavior. Recent experiments have demonstrated an electrophysiological marker of VWM encoding and maintenance, the contralateral delay activity (CDA), which has been shown in multiple tasks that have both explicit and implicit memory demands. Here, we investigate whether the CDA is evident during visual search, a thoroughly-researched task that is a hallmark of visual attention but has no explicit memory requirements. Methodology/Principal Findings: The results demonstrate that the CDA is present during a lateralized search task, and that it is similar in amplitude to the CDA observed in a change-detection task, but peaks slightly later. The changes in CDA amplitude during search were strongly correlated with VWM capacity, as well as with search efficiency. These results were paralleled by behavioral findings showing a strong correlation between VWM capacity and search efficiency. Conclusions/Significance: We conclude that the activity observed during visual search was generated by the same neura

    Cognitive-behavioral and electrophysiological evidence of the affective consequences of ignoring stimulus representations in working memory

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    Ignoring visual stimuli in the external environment leads to decreased liking of those items, a phenomenon attributed to the affective consequences of attentional inhibition. Here we investigated the generality of this “distractor devaluation” phenomenon by asking whether ignoring stimuli represented internally within visual working memory has the same affective consequences. In two experiments we presented participants with two or three visual stimuli and then, after the stimuli were no longer visible, provided an attentional cue indicating which item in memory was the target they would have to later recall, and which were task-irrelevant distractors. Participants subsequently judged how much they liked these stimuli. Previously-ignored distractors were consistently rated less favorably than targets, replicating prior findings of distractor devaluation. To gain converging evidence, in Experiment 2, we also examined the electrophysiological processes associated with devaluation by measuring individual differences in attention (N2pc) and working memory (CDA) event-related potentials following the attention cue. Larger amplitude of an N2pc-like component was associated with greater devaluation, suggesting that individuals displaying more effective selection of memory targets—an act aided by distractor inhibition—displayed greater levels of distractor devaluation. Individuals showing a larger post-cue CDA amplitude (but not pre-cue CDA amplitude) also showed greater distractor devaluation, supporting prior evidence that visual working-memory resources have a functional role in effecting devaluation. Together, these findings demonstrate that ignoring working-memory representations has affective consequences, and adds to the growing evidence that the contribution of selective-attention mechanisms to a wide range of human thoughts and behaviors leads to devaluation

    Metarhizium anisopliae Pathogenesis of Mosquito Larvae: A Verdict of Accidental Death

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    Metarhizium anisopliae, a fungal pathogen of terrestrial arthropods, kills the aquatic larvae of Aedes aegypti, the vector of dengue and yellow fever. The fungus kills without adhering to the host cuticle. Ingested conidia also fail to germinate and are expelled in fecal pellets. This study investigates the mechanism by which this fungus adapted to terrestrial hosts kills aquatic mosquito larvae. Genes associated with the M. anisopliae early pathogenic response (proteinases Pr1 and Pr2, and adhesins, Mad1 and Mad2) are upregulated in the presence of larvae, but the established infection process observed in terrestrial hosts does not progress and insecticidal destruxins were not detected. Protease inhibitors reduce larval mortality indicating the importance of proteases in the host interaction. The Ae. aegypti immune response to M. anisopliae appears limited, whilst the oxidative stress response gene encoding for thiol peroxidase is upregulated. Cecropin and Hsp70 genes are downregulated as larval death occurs, and insect mortality appears to be linked to autolysis through caspase activity regulated by Hsp70 and inhibited, in infected larvae, by protease inhibitors. Evidence is presented that a traditional host-pathogen response does not occur as the species have not evolved to interact. M. anisopliae retains pre-formed pathogenic determinants which mediate host mortality, but unlike true aquatic fungal pathogens, does not recognise and colonise the larval host

    Electrophysiological correlates of the fexible allocation of visual working memory resources

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    Visual working memory is a brief, capacity-limited store of visual information that is involved in a large number of cognitive functions. To guide one’s behavior effectively, one must efficiently allocate these limited memory resources across memory items. Previous research has suggested that items are either stored in memory or completely blocked from memory access. However, recent behavioral work proposes that memory resources can be flexibly split across items based on their level of task importance. Here, we investigated the electrophysiological correlates of flexible resource allocation by manipulating the distribution of resources amongst systematically lateralized memory items. We examined the contralateral delay activity (CDA), a waveform typically associated with the number of items held in memory. Across three experiments, we found that, in addition to memory load, the CDA flexibly tracks memory resource allocation. This allocation occurred as early as attentional selection, as indicated by the N2pc. Additionally, CDA amplitude was better-described when fit with a continuous model predicted by load and resources together than when fit with either alone. Our findings show that electrophysiological markers of attentional selection and memory maintenance not only track memory load, but also the proportion of memory resources those items receive
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