Abstract. At CRYPTO '94, Tillich and Zémor proposed a family of hash functions, based on computing a suitable matrix product in groups of the form SL2(F2n ). We show how to construct collisions between palindromic bit strings of length 2n + 2 for Tillich and Zémor's construction. The approach also yields collisions for related proposals by Petit et al. from ICECS '08 and CT-RSA '09. It seems fair to consider our attack as practical: for parameters of interest, the colliding bit strings have a length of a few hundred bits and can be found on a standard PC within seconds.

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Objective: To determine the cost-effectiveness/utility of a superabsorbent wound dressing (Zetuvit Plus Silicone) versus the current standard of care (SoC) dressings, from the NHS perspective in England, in patients with moderate-to-high exudating leg ulcers. Method: A model-based economic evaluation was conducted to analyse the cost-effectiveness/utility of a new intervention. We used a microsimulation state-transition model with a time horizon of six months and a cycle length of one week. The model uses a combination of incidence base and risk prediction approach to inform transition probabilities. All clinical efficiency, health-related quality of life (HRQoL), cost and resource use inputs were informed by conducting a systematic review of UK specific literature. Results: Treatment with the superabsorbent dressing leads to a total expected cost per patient for a six month period of £2887, associated with 15.933 expected quality adjusted life weeks and 10.9% healing rate. When treated with SoC, the total expected cost per patient for a six month period is £3109, 15.852 expected quality adjusted life weeks and 8% healing rate. Therefore, the superabsorbent dressing leads to an increase in quality-adjusted life weeks, an increase in healing rate by 2.9% and a cost-saving of £222 per single average patient over six months. Results of several scenario analyses, one-way deterministic sensitivity analysis, and probabilistic sensitivity analysis confirmed the robustness of base-case results. The probabilistic analysis confirmed that, in any combination of variable values, the superabsorbent dressing leads to cost saving results. Conclusion: According to the model prediction, the superabsorbent dressing leads to an increase in health benefits and a decrease in associated costs of treatment.

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Tourism is often defined as an economic sector that deals with innovation and production of tourism products and services. It is a very complex economic sector, since tourism products and stakeholders are constantly changing due to changing external forces. Therefore, development and progress of information and communication technology have had an enormous impact on tourism as well as on other sectors of the economy associated with it. Over the years, the use of modern technology in tourism has been expanded to provide a wider range of products and services to tourists all over the world, and is a key determinant of competitiveness in this sector. The subject of this paper is a look at the implications of modern technology for the tourism sector of the Republic of Serbia and the ways in which it contributes to increasing competitiveness. The analysis relies on the World Economic Forum methodology for the presentation of competitiveness of the travel and tourism sector, namely the Travel and Tourism Competitiveness Index. The aim of the paper is to examine the degree of contribution of ICT readiness pillar to the competitiveness of the tourism sector in the Republic of Serbia. ИМПЛИКАЦИЈЕ РАЗВОЈА САВРЕМЕНИХ ТЕХНОЛОГИЈА НА СЕКТОР ТУРИЗМА РЕПУБЛИКЕ СРБИЈЕАпстракт Туризам се често дефинише као сектор привреде који се бави иновирањем и производњом туристичких производа и услуга. Изузетно је сложен сектор привреде с обзиром на то да се туристички производи и актери стално мењају због промена спољашњих снага. Стога је развој и напредак информацино комуникационе технологије имао огроман утицај на туризам као и на остале секторе привреде повезане са њим. Током година, употреба савремених технологија у туризму је унапређи-1 ivanica1404@yahoo.com P. 37-52 ©Друштво економиста "Економика" Ниш http://www.ekonomika.org.rs 38 ЕКОНОМИКА вана за прижање што ширег дијапазона производа и услуга туристима широм света и кључна је детерминанта конкурентности у овом сектору. Предмет овог рада јесте сагледавање импликација које савремене технологије оставрују н асектор туризма Републике Србије и начина на који доприносе повећању конкурентности. За анализу у раду коришћена је методологија Светског економског форума за приказивање конкурентности сектора путовања и туризма тачније Индекс конкурентности путовања и туризма .Циљ рада је испитати степен доприноса пилара спремност информационо комуникационе технологије (ИЦТ спремност) на конкурентност сектора туризма у Републици Србији. Кључне речи: туризам, информационокомуникационе технологије, конкурентност ЕКОНОМИКА ©Друштво економиста "Економика" Ниш