On the Complexity of tt-Closeness Anonymization and Related Problems

An important issue in releasing individual data is to protect the sensitive information from being leaked and maliciously utilized. Famous privacy preserving principles that aim to ensure both data privacy and data integrity, such as $k$-anonymity and $l$-diversity, have been extensively studied both theoretically and empirically. Nonetheless, these widely-adopted principles are still insufficient to prevent attribute disclosure if the attacker has partial knowledge about the overall sensitive data distribution. The $t$-closeness principle has been proposed to fix this, which also has the benefit of supporting numerical sensitive attributes. However, in contrast to $k$-anonymity and $l$-diversity, the theoretical aspect of $t$-closeness has not been well investigated. We initiate the first systematic theoretical study on the $t$-closeness principle under the commonly-used attribute suppression model. We prove that for every constant $t$ such that $0\leq t<1$, it is NP-hard to find an optimal $t$-closeness generalization of a given table. The proof consists of several reductions each of which works for different values of $t$, which together cover the full range. To complement this negative result, we also provide exact and fixed-parameter algorithms. Finally, we answer some open questions regarding the complexity of $k$-anonymity and $l$-diversity left in the literature.Comment: An extended abstract to appear in DASFAA 201

Speed Management in Small Cities and Towns—Guidelines for Indiana

Many small cities and towns in rural states such as Indiana are crossed by arterial highways. The local traffic on these roads, particularly vulnerable road users, face the excessive risk of injury and death. This danger is amplified with local land development, driveways, and on-street parking in town centers. This report presents an Indiana study of the speeding problem on arterial roads passing through small communities. Past research on various countermeasures suitable for the studied conditions were identified and the connection between speed reduction and safety improvements was investigated in a sample of Indiana small towns. Promising speed-reduction measures include speed feedback signs and converging chevrons with speed limit legends marked on the pavement. Point-to-point enforcement is a modern and highly effective alternative that may be applicable on highways passing small towns if the through traffic prevails with limited interruptions. This report provides a method of evaluating the benefits of speed reduction in the studied conditions where the risk of severe injury and fatality is excessive to road users while the frequency of crashes is low. The method includes the proactive estimation of the economic benefit. The results indicate that both the local and through traffic on highways passing a small town benefit considerably from speed reduction even after accounting for the loss of time. An Excel spreadsheet developed in the study facilitates the calculations

Catalytic hydroprocessing of lignin β-O-4 ether bond model compound phenethyl phenyl ether over ruthenium catalysts

The catalytic hydroprocessing of phenethyl phenyl ether (PPE), a model compound of one of the most significant ether linkages within lignin structure, β-O-4, has been studied. Reactions were carried out using two ruthenium-based catalysts, supported on different materials: 3.8 wt.% Ru/C and 3.9 wt.% Ru/Al2O3. Aiming at studying the reaction mechanism, experiments were carried out at 150 °C and 25 bar in H2 atmosphere, with varying feed to catalyst mass ratios and reaction time. Differences between the relative importance of the steps of the mechanism were observed when using those two catalysts. The most significant finding was the predominance of the cleavage of Cβ-O bonds compared to the cleavage of the Caryl-O when using Ru/Al2O3 as catalyst; whereas with Ru/C, the two routes were nearly equivalent. It has been observed that the kinetic model describes the general tendencies of consumption and formation of the different products, but some over/under estimation of concentrations occurs. Finally, the effect of temperature was also explored by carrying out reactions at 100 and 125 °C, observing that decreasing temperature from 150 to 125 or 100 °C favored the dimer hydrogenation route versus the hydrogenolysis of the ether bonds

The complexity of soil biological sustainability

Additions of organic amendments to soil not only compensate for decreased soil C, but also contribute to energy requirements for conserving biological activity levels. The soil microbial biomass displays some highly conserved, and possibly unique, characteristics that do not permit a classic interpretation of microbial metabolic parameter data. The resilience of soil microbial biomass and the role of soil organic matter in sustaining microbial biomass under practically zero C inputs were assessed in two long term incubation experiments using soils from the Broadbalk experiment at Rothamsted (UK). Soils with low organic C contents, showed the greatest decline in biomass C during the first 30 d of incubation. The ATP concentration of this rapidly declining microbial biomass did not change during the prolonged incubation period, confirming this peculiar character of the soil microbial biomass. Specific respiration rate did not depend upon substrate availability, being higher in soils that had received the lowest C inputs. Qualitative and quantitative changes observed in humic fractions suggest that humified soil organic matter is a much more dynamic soil fraction than is normally considered and provides a utilizable energy reserve for soil microorganisms. Carbon levels can be successfully restored in soils through practices such as incorporation of crop residues, re\u2010vegetation and application of manures, biosolids and composts. Some amendments, such as olive mill waste compost, promote incorporation of altered lignin structures, N\u2010containing compounds and carbohydrates into humic acids. The mineral\u2010bound fraction of humic C also increases, after their addition, and contributes to the accumulation of the most inert soil C pools

Pharmaceutical management and planning: implementation of PBL. Methodology implemented through group work

La implantación del EEES supone un importante reto para la docencia de numerosas universidades europeas y permite desarrollar iniciativas de innovación docente; esto es lo que en los últimos años se ha venido haciendo en diversas asignaturas de la Facultad de Farmacia de la Universidad de Sevilla. En este sentido, la asignatura de Gestión y Planificación, por su carácter eminentemente práctico, está especialmente indicada para implementar diversas actividades de innovación docente, entre ellas, el Aprendizaje Basado en Problemas (ABP). La estrategia docente consiste en el desarrollo en grupos reducidos de alumnos de un plan de marketing y/o merchandising en una oficina de farmacia concreta. Se pretende el desarrollo de cinco competencias genéricas: buscar información, trabajar en equipo, debatir en grupo y tomar decisiones, elaborar informes, y defender y debatir su trabajo en público. Desde la implantación generalizada de este tipo de actividad en el curso 2007/08 se comprueba una mayor implicación del alumno en la asignatura que se traduce en una mayor participación en el ABP, en el examen oficial, y en un mayor porcentaje de aprobados.The implementation of the EHEA is an important challenge for the teaching of many universities in Europe and enables the development of innovative teaching initiatives; this is what in recent years has been doing in different subjects of the Faculty of Pharmacy, University of Seville. In this sense, the subject of Management and Planning, by its practical nature, is suited to implement various activities of educational innovation, including Problem Based Learning (PBL). The teaching strategy is the development in small groups of students in a marketing plan and/or merchandising in a specific pharmacy. The aim is the development of five generic skills: searching for information, teamwork, group discussions and decisions, prepare reports, and defend and discuss their work in public. Since the widespread deployment of this type of activity during 2007/08 is found greater involvement of students in the subject that translates into greater participation in PBL, in the official examination, and a better pass rate

Karnofsky performance score in acute renal failure as a predictor of short-term survival

Karnofsky Performance Scale Index (KPS) is a measure of functional status that allows patients to be classified according to their functional impairment. We aim to assess if the prior KPS may predict the risk of death among patients with acute renal failure (ARF). METHODS: A cohort of 668 consecutive patients who had been admitted in an university-affiliated hospital between June 2000 and June 2006, and had been diagnosed with ARF, were studied. Three hundred and eighty-six patients with ARF who matched at least one of the RIFLE (Risk, Injury, Failure, Loss and End stage) criteria on increased serum creatinine were included for subsequent analysis. The group was divided into four categories, according to different Karnofsky scores measured by a nephrologist (>or=80, 70, 60 and <or=50). We used an adjusted logistic regression model to assess the relationship between the Karnofky score and mortality. RESULTS: A significant risk of in-hospital mortality within 90 days was observed when the other groups were compared with the >or=80 Karnofsky group. Adjusted odds ratios were 8.87 (95% confidence interval (CI) 3.03-25.99), 6.78 (95% CI 2.61-17.58) and 2.83 (95% CI 1.04-7.68), for Karnofsky groups of <or=50, 60 and 70, respectively. An adjusted odds ratio of 1.75 (95% CI 1.37-2.23) was observed for every 10 point decrease in KPS score. CONCLUSION: Functional status as indicated by the KPS is an independent predictor of death in this cohort of patients with ARF. Patients who presented lower scores had increased mortality rate

Evaluation of the prognostic value of the risk, injury, failure, loss and end-stage renal failure (RIFLE) criteria for acute kidney injury

AIM: The experts have argued about the use of the risk, injury, failure, loss and end-stage renal failure (RIFLE) criteria as a prognosis scoring system. We examined the association between in-hospital mortality and the RIFLE criteria, and discussed its accuracy as a prognosis factor. METHODS: In this prospective study, we analysed the data gathered from a cohort of 956 patients admitted in a Spanish tertiary hospital between January 1998 and April 2006. Hazard ratios for mortality, and survival curves within 60 days were calculated. Discrimination and calibration of the model were also assessed. RESULTS: Excluding 53 patients, 903 patients were finally analysed. We classified them into groups according to the maximum RIFLE class reached during their admission. The RIFLE class was assessed by the glomerular filtration rate criterion. We found an increase in the in-hospital mortality risk. Cox proportional hazard models showed that RIFLE classes risk, injury, and failure were significant predictive factors (hazard ratios were 2.77, 3.23 and 3.52, respectively; P for trend was 0.005). The multivariate analyses from the cross-classification of the participants according to Liano score values (severity of illness) and RIFLE classes showed additive effects of the exposures on in-hospital mortality. CONCLUSION: In this population, the risk of in-hospital mortality during the acute kidney injury (AKI) episode was positively associated with RIFLE classes. We showed that the RIFLE classification system had discriminative power in predicting hospital mortality within 60 days in AKI patients, but not better than a specific AKI predictive model. However, a combined use of both may give a more robust prognosis system