A CAPTCHA model based on visual psychophysics: Using the brain to distinguish between human users and automated computer bots

Demand for the use of online services such as free emails, social networks, and online polling is increasing at an exponential rate. Due to this, online service providers and retailers feel pressurised to satisfy the multitude of end-user expectations. Meanwhile, automated computer robots (known as “bots”) are targeting online retailers and service providers by acting as human users and providing false information in order to abuse their service provisioning. CAPTCHA is a set of challenge/response protocol, which was introduced to protect online retailers and service providers from misuse and automated computer attacks. Text-based CAPTCHAs are the most popular form, and are used by most online service providers to differentiate between the human users and bots. However, the vast majority of text-based CAPTCHAs have been broken using the Optical Character Recognition (OCR) techniques and thus, reinforces the need for developing a secure and robust CAPTCHA model. Security and usability are the two fundamental issues that pose a trade-off in the design of a CAPTCHA; a hard CAPTCHA model could also be difficult for human users to resolve, which affects its usability, and vice versa. The model developed in this study uses the unsurpassed abilities of the Human Visual System (HVS) to superimpose and integrate complex information presented in individual frames, using the mechanism of trans-saccadic memory. In this context, the model integrates in its design the concept of persistence of vision, which enables humans to see the world in a continuous fashion. Preliminary results from the proposed model based on this technique are encouraging. To ensure the usability of the proposed CAPTCHA model, we set the threshold for the ORO parameter at 40%. This ensured that our CAPTCHA strings would be recognised by human observers at a rate of over 99% (or as close to 100% as is realistic). In turn, when examining the robustness of our VICAP model to computer programme attacks, we can observe that for the traditional case of OCR recognition, based on a single-frame scenario, the Computer Recognition Success Rate (CRSR) was about 0%, while in the case of a multi-frame scenario, the CRSR could increase to up to 50%

Different countries different cultures : Germany vs Sweden

Title: Different countries – different cultures Level: Thesis for Bachelor Degree in Business Administration Authors: Cecilia Jensen and Changiz Saadat Behesthi Supervisor: Lars Ekstrand Date: 2011 – 12  Our study is based on two countries, Sweden and Germany, and is aiming to find out if the cultural differences between the two countries have a major impact when doing business together or not.Cross-cultural management is a modern topic and can help transnational companies deal with problems that occur due to different cultures in the organization, but is it really necessary to spend huge amount on intercultural training? We used a qualitative method and did a survey through a convenience sampling among six managers in the two countries. We analyzed the answers sorted by country and then compared them to each other. The result of the survey was that Swedish managers inform and include their staff in decisions to a bigger extend than German managers. Other than the preferences of a more democratic leadership the differences were, according to us, insignificant to perform any cultural training between the two countries. For further studies we suggest a deeper research method with a field study at every workplace, to conclude that the manager’s answers concurred to the actual outcome. We also think that interviewing more managers, and within the same branch, would increase the creditability of the study. The result indicates that the money spent on intercultural training between Sweden and Germany is quite unnecessary and that the differences are smoothing out.

QSAR modeling of antimalarial activity of urea derivatives using genetic algorithm–multiple linear regressions

A quantitative structure–activity relationship (QSAR) was performed to analyze antimalarial activities of 68 urea derivatives using multiple linear regressions (MLR). QSAR analyses were performed on the available 68 IC50 oral data based on theoretical molecular descriptors. A suitable set of molecular descriptors were calculated to represent the molecular structures of compounds, such as constitutional, topological, geometrical, electrostatic and quantum-chemical descriptors. The important descriptors were selected with the aid of the genetic algorithm (GA) method. The obtained model was validated using leave-one-out (LOO) cross-validation; external test set and Y-randomization test. The root mean square errors (RMSE) of the training set, and the test set for GA–MLR model were calculated to be 0.314 and 0.486, the square of correlation coefficients (R2) were obtained 0.801 and 0.803, respectively. Results showed that the predictive ability of the model was satisfactory, and it can be used for designing similar group of antimalarial compounds

The effect of abobotulinum toxin A in the prophylactic treatment of refractory migraine

Objective: Some patients with migraine headache still experience severe migraine attacks despite use of proper prophylactic treatments. There are several treatments for refractory migraine (RM), one of which is abobotulinum toxin A (Dysport). This study aimed to investigate the efficacy of abobotulinum toxin A in the prophylactic treatment of RM. Materials and Methods: In this prospective single-arm clinical trial, 18 patients with RM were included. Patients completed a questionnaire including migraine characteristics one month before the study. Each patient received an injection of 150 U abobotulinum toxin A in the specific head and neck regions. Before and 3 months after treatment, migraine severity was evaluated. Results: The average number of attacks per month before injection was 7.56±4.06, which decreased to 1.89±1.32 3 months after injection (p<0.0001). The average duration of attacks also decreased significantly after 3 months of injection (from 20.33 hrs to 2.56 hrs per month) (p=0.0001). Three patients (16.6%) had no attacks during the follow-up period. Eleven patients (61.1%) reported mild attacks and four patients (22.2%) reported moderate pain. Conclusion: Abobotulinum toxin A (Dysport) can reduce frequency, duration, and severity of migraine attacks in patients with RM and it can be used as a prophylactic treatment in this group of patients

One-year prevalence and the association between SARS-CoV-2 cycle threshold, comorbidity and outcomes in population of Babol, North of Iran (2020-2021)

Background: The present study aimed to investigate the one-year prevalence of SARS-CoV-2, common comorbidities and demographic information among negative- and positive rRT-PCR in health care workers (HCW), hospitalized and outpatients. Also, the association between SARS-CoV-2 cycle threshold (Ct) and the outcomes of patients were analyzed in Babol, northern Iran. Methods: This large retrospective cross-sectional study was performed between March 2020 and March 2021. The records of 19232 hospitalized, outpatients and HCW suspected to COVID-19 were collected from teaching hospitals in the North of Iran. Results: Out of the 19232 suspected to COVID-19 patients, 7251 (37.7) had a positive rRT-PCR result; 652 (9), 4599 (63.4) and 2000 (27.6) of those were categorized as HCW, hospitalized and outpatients, respectively. Moreover, between the hospitalized and the outpatient group, 10.2 and 0.8 cases died, whereas no death cases were reported in the HCW. Furthermore, it seems that death rate was significantly different between the three groups of Ct value, the highest mortality in those with Ct between 21 and 30 (group B=7.6) and the lowest in the group with the highest Ct (between 31 and 40 = 5.5) (p<0.001). Conclusion: In summary, 37.7 of cases were positive for SARS-CoV-2; of which, 63.4, 27.6 and 9 were hospitalized, outpatients and HCW, respectively. With regard to the mortality rate in hospitalized patients and the significant association with Ct under 20 and 30, it seems that the early detection and the initial quantification of SARS-CoV-2 in the first week of the conflict and therapeutic considerations to reduce the relative load can reduce the mortality rate. © The Author(s)