HPPC: Hidden Product of Polynomial Composition

The article introduces HPPC a new Digital Signature scheme that intends to resist known previous attacks applied to HFE-based schemes like QUARTZ and GeMSS. The idea is to use maximal degree for the central HFE polynomial whereas the trapdoor polynomial has low degree in order to sign messages by finding polynomial roots in an extension field via Berlekamp\u27s algorithm. This work has been submitted to NIST\u27s Post-Quantum Cryptography challenge (PQC) and code is available at https://github.com/kub0x/MPKC-HPP

Effects of Web Experience factors on virtual retail purchase preferences

This article examines the effects of different elements of the Web Experience (WE) on the buying behaviour of virtual consumers, specifically on the choice of the online retail vendor. The purpose of the study is to empirically test the theoretical findings as to the main parameters of the online customer experience and measure their relative importance and role as inputs in the customer’s decision-making process. The study was conducted by means of an online consumer survey in a realistic virtual shopping environment. The results of the study show that out of the five web experience components analyzed, four (the usability, trust building, marketing mix and aesthetics) have a positive and significant effect on the choice of e-vendor while the fifth one (interactivity) does not seem to positively influence the choice of an online vendor. Furthermore the study examines the effect of two behavioural variables (experience and motivation) on the choice of online -vendors. This topic could expand the scope of academic research on the issue of online marketing and at the same time provide online marketers with new insights and tools for building a commercially successful online presence

Burnable Pseudo-Identity: A Non-Binding Anonymous Identity Method for Ethereum

The concept of identity has become one common research topic in security and privacy where the real identity of users must be preserved, usually covered by pseudonym identifiers. With the rise of Blockchain-based systems, identities are becoming even more critical than before, mainly due to the immutability property. In fact, many publicly accessible Blockchain networks like Ethereum rely on pseudonymization as a method for identifying subject actions. Pseudonyms are often employed to maintain anonymity, but true anonymity requires unlinkability. Without this property, any attacker can examine the messages sent by a specific pseudonym and learn new information about the holder of this pseudonym. This use of Blockchain collides with regulations because of the right to be forgotten, and Blockchain-based solutions are ensuring that every data stored within the chain will not be modified. In this paper we define a method and a tool for dealing with digital identities within Blockchain environments that are compliant with regulations. The proposed method provides a way to grant digital pseudo identities unlinked to the real identity. This new method uses the benefits of key derivation systems to ensure a non-binding interaction between users and the information model associated with their identity. The proposed method is demonstated in the Ethereum context and illustrated with a case study.PoSeID-on is a project funded by the European Commission. This project has received funding from the European Union’s Horizon 2020 program under Grant Agreement n◦ 786713

Asymptomatic Spontaneous Pneumopericardium in a Young Post-COVID-19 Patient: A Case Report

Background: Pneumopericardium is a rare clinical condition which is defined as the presence of air or gas in the pericardial cavity. Although uncommon to see, it can present after chest trauma, barotrauma, fistula between the pericardium and surrounding structures, gas producing microorganisms and iatrogenic causes. But spontaneous presentations are even more uncommon. Coronavirus Disease 2019 (COVID 19) infection became a large global epidemic and in addition to respiratory symptoms, involvement of other organs such as pericardium was also reported. We here present a young patient post COVID 19 infection with isolated spontaneous pneumopericardium. Case Presentation: A 19 year old patient with a past medical history of ADD and general anxiety disorder presented to the emergency department with worsening abdominal pain of 4 day duration, that started after having lunch at a family gathering. The pain progressed to colicky pain with no radiation and was associated with dysuria. Of note, 2 weeks prior the patient had a COVID 19 infection associated with a non productive cough, for which she received supportive treatment. She denied any shortness of breath, chest pain, paresthesias or paresis, recent trauma, any cannulations, and recent diving. No history of illicit drug use. Vitals were unremarkable. Physical examination showed suprapubic tenderness. Urinalysis included presence of moderate leukocyte esterase, WBC 10 25 and 5 10 RBC. The Urine pregnancy test was negative. Due to the abdominal pain and concern for appendicitis, CT (Computed Tomography) scan of the abdomen and pelvis with contrast was ordered and did not reveal any acute intra abdominal or pelvic process, but there was an incidental finding of air presence in the pericardial space. An immediate CT of the chest without contrast was ordered and it did not reveal any pneumopericardium or pneumomediastinum. Pelvic US was performed later to evaluate for potential causes; and was unremarkable. Patient was admitted under observation for management of UTI (Urinary Tract Infection). She remained stable without any shortness of breath or chest pain and her abdominal pain improved in the first 24 hours. She was later discharged with oral antibiotics for UTI. Conclusion: Pneumopericardium is a rare but potentially life threatening condition. The most common clinical presentation is with chest pain, dyspnea and/or hemodynamic instability if large enough to produce tamponade physiology. In this case, the patient had a recent COVID 19 infection with cough. COVID 19 infection is associated with alveolar rupture and hyperinflammatory response, which could increase the risk of pneumopericardium, but the exact mechanism has not been elucidated. Since most of the patients with COVID 19 have a mild clinical presentation, the incidence of pneumopericardium is difficult to evaluate and the symptoms easily be obscured by the constellation of symptoms these patients present. In this patient, the repeat CT of the chest was unable to find the presence of air, which was consistent with improvement of the patients abdominal pain. This could have been because of migration of air or reabsorption, which correlates to the self limiting nature of this disease

Yield Management As A Pricing Mechanism

Consumers nowadays frequently make their purchases online. One common pricing strategy on the Internet is demand-based pricing, which allows firms to adapt prices to the demand for their products. This mechanism can undoubtedly be employed more efficiently on the Internet, due to how quickly demand information can be obtained. Within demand-based pricing, one very well-known practice is yield management. This practice was pioneered by airlines, but has spread in recent years to industries such as hotels, rental cars and cruise lines to name but a few industries. The application of yield management was an authentic revolution for the traditional concept of pricing, but has shown that it can be a good strategy when used correctly. Applying yield management requires firms to understand consumer purchasing behavior in order to compare present demand with the demand that is anticipated in the future. Yield management techniques imply the allocation of a fixed capacity to different prices and segments of consumers in order to maximize income. Yield management is sometimes confused with a well-known segmentation strategy called time-based pricing. For this reason, in this paper we highlight the main demand-based pricing strategies that are now being used on the Internet, placing special emphasis on yield management

Do You Have Social Profile? Users And Non-Users Of Social Networking Sites In The Web 2.0

In light of the increasing importance of Social Networking Sites (SNSs) for both personal and professional relationships, the aim of this work is to contribute to the knowledge framework regarding the interactive behaviour of Internet users, particularly within Web 2.0, describing its evolution from Web 1.0. Moreover, this paper analyses the different behaviours on the Web by people who use or not use SNSs, as well as to determine whether any such differences are significant in order to discover the reasons why these people participate. As results, initial characterization of the users themselves is followed by an analysis of the main differences between users and non-users of these applications. With this information, companies can play an active role in this Social Web by becoming company 2.0 and participating actively in already existing SNSs or creating their own social network service

Transient Sinus Node Dysfunction in a Postpartum Female with Sinus Bradycardia: A Case Report

Background: Conduction disorders are common cardiac complications during pregnancy in women with and without structural heart disease. Sinus bradycardia has been described in few case reports secondary to increased vagal tone. Prevalence of newly acquired sinus node dysfunction without structural heart disease is unknown. In this case, we present a post-partum female with symptomatic acquired sinus node dysfunction who presented with severe sinus bradycardia. Case Presentation: A 32-year-old Hispanic lady with a past medical history of obesity and obstetric formula of G4P4, who recently delivered her 4th child via C-section 4 weeks prior, presented to the Women´s Hospital as a transfer due to 4-day history of abdominal pain and subjective fever. Patient stated that her delivery was uneventful, and she was discharged 3 days later with iron pills due to recently diagnosed iron deficiency anemia. She complained of sudden onset episodes of subjective fever, that were associated with chills, diaphoresis, and abdominal pain on the incision site. These episodes were not associated with any foul discharge. She denied any history of heart disease in the past. She presented to an urgent care clinic and CT abdomen and pelvis without contrast revealed a collection anterior to the left uterine wall, suspicious for an abscess. She was later transferred to Women´s hospital and her vital signs were T 98.4, HR 65 BPM, RR 18 and BP 122/87 mm Hg. Her physical exam was remarkable for tenderness at the incision site, with no redness, pus expression, rebound or guarding. She was started on broad spectrum antibiotics and underwent emergent CT guided fluid collection with Fentanyl for pain management. Minimal drainage of dark blood was collected. Four days after procedure, patient suddenly became bradycardic. Her vitals were HR 37 bpm, BP 77/51 mm Hg and EKG was consistent with sinus bradycardia. Labs did not reveal any electrolyte abnormalities, cardiac enzymes, TSH and chest radiograph were within normal limits. Due to lack of response to atropine, the patient was transferred to ICU after placement of transvenous pacemaker. Emergent echocardiogram revealed normal left ventricular function, ejection fraction between 60-70% and normal RVSP. Two days later, her pacemaker was turned off and her baseline was sinus rhythm with a rate in the 60s. Leads of transvenous pacemaker were then removed and she was later discharged with close follow up with Cardiology and OBGYN. Conclusions: Sinus bradycardia can be due to various medical conditions, including secondary to vasovagal response. This is called hypervagotonic sinus node dysfunction (HSND). HSND can be due to intrinsic abnormalities as well as secondary causes such as infections or drugs. Usually, HSND can be treated with conservative management. In our case, four days after the patient underwent interventional procedure, the patient presented symptoms consistent with sinus bradycardia. Holter monitoring and echocardiogram did not reveal significant abnormalities and after 24-48 hours it improved with conservative measures. This is an uncommon and unexpected presentation; however, further studies are required to understand if there is presence of predisposing factors in such population to present this abnormality

Application Of Social Web Tools To The Internationalization Of Retail Companies

The emergence and development of what is called the Social Web or Web 2.0 is marked by the appearance and development of new communication tools and applications such as blogs, chats, forums, social networks, etc., and interaction between users. As well as giving consumers emotional and practical benefits, these applications represent great communication opportunities for companies in a globalized context. For this reason, businessmen are increasingly using Social Web tools as instruments to get information and market knowledge, as well as for communication in an internationalization context. Taking the opportunities the use of Social Web tools in a global context represent for retail business as its starting point, this study analyzes the possibilities offered by different tools in the context of the internationalization process of retail distribution businesses, and the uses retailers involved in internationalization processes are currently putting them to. In order to do this, a study is being made by direct observation of the applications and social contents on their web sites, and exploration and monitoring of their presence in other social spaces (blogs, social networks, microblogging, etc.)

Analysis Of Hotel Internet Booking Users

The number of tourist products sold on the Internet has increased remarkably in recent years. The hotel industry has figured prominently in this boom due to hotel bookings made via the Internet becoming increasingly popular. The reason for this upturn in online bookings is, in many cases, the possibility of booking at any time and the possible existence of lower prices. In order to achieve these lower prices, consumers must accept certain restrictions or conditions that hotels use to manage demand through yield management strategies.This paper analyses hotel Internet booking users in order to ascertain their socio-demographic characteristics and behaviour in regard to online purchase decisions. The ultimate goal is therefore to determine a user profile. With this information, hotel managers will be able to manage Internet hotel bookings