Estimating graph parameters with random walks

An algorithm observes the trajectories of random walks over an unknown graph $G$, starting from the same vertex $x$, as well as the degrees along the trajectories. For all finite connected graphs, one can estimate the number of edges $m$ up to a bounded factor in $O\left(t_{\mathrm{rel}}^{3/4}\sqrt{m/d}\right)$ steps, where $t_{\mathrm{rel}}$ is the relaxation time of the lazy random walk on $G$ and $d$ is the minimum degree in $G$. Alternatively, $m$ can be estimated in $O\left(t_{\mathrm{unif}} +t_{\mathrm{rel}}^{5/6}\sqrt{n}\right)$, where $n$ is the number of vertices and $t_{\mathrm{unif}}$ is the uniform mixing time on $G$. The number of vertices $n$ can then be estimated up to a bounded factor in an additional $O\left(t_{\mathrm{unif}}\frac{m}{n}\right)$ steps. Our algorithms are based on counting the number of intersections of random walk paths $X,Y$, i.e. the number of pairs $(t,s)$ such that $X_t=Y_s$. This improves on previous estimates which only consider collisions (i.e., times $t$ with $X_t=Y_t$). We also show that the complexity of our algorithms is optimal, even when restricting to graphs with a prescribed relaxation time. Finally, we show that, given either $m$ or the mixing time of $G$, we can compute the "other parameter" with a self-stopping algorithm

Effect of abiotic stresses on bioactive contents of vegetables and high-pressure technology in related functional beverages

[SPA] Los compuestos fenólicos son fitoquímicos con propiedades beneficiosas para la salud, presentes en gran medida en las frutas y verduras, como la zanahoria o el brócoli. La zanahoria es una verdura ampliamente consumida en todo el mundo. Sin embargo, su contenido fenólico es relativamente bajo en comparación a otras verduras. Consecuentemente, el aumento de los niveles de compuestos fenólicos en zanahorias, usando estreses abióticos, por ejemplo, podría agregar un valor añadido a esta verdura para las industrias alimentaria y farmacéutica. El ácido clorogénico representó el 70 % de la suma de los compuestos fenólicos en las zanahorias estudiadas. Los compuestos fenólicos totales (TPC en inglés) estuvieron altamente correlacionados con la capacidad antioxidante total (TAC en inglés) con un R2=0,82. Se comprobó que los estreses abióticos, como el cortado y la conservación en atmósfera de alto oxígeno (80 kPa O2), indujeron un elevado aumento de la enzima fenilalanina amonio liasa (PAL en inglés), TPC y TAC en zanahorias durante una conservación a 15 ºC durante 72 h. Aunque el pretratamiento de la zanahoria rallada con una dosis intermedia (9 kJ m-2) de radiación UV-C redujo la acumulación de compuestos fenólicos, se registró un incremento del 600 % en estas muestras almacenadas en alto oxígeno durante 72 h. Las primeras conclusiones de esta tesis doctoral, resultan útiles para las industrias farmacéutica y alimentaria, por obtener una gran fuente de compuestos bioactivos de esta verdura, y probablemente, aplicable en otros productos vegetales A continuación, se estudió el efecto de pretratamientos con radiación UV-B (1,5 kJ m-2) sobre los contenidos de PAL/TPC/TAC en zanahoria rallada y su combinación con una dosis bajo-intermedia (4 kJ m-2) de radiación UV-C. El pretratamiento con UV-B provocó el máximo aumento de PAL y TPC de 760 y 498 %, respectivamente, tras 72 h a 15 ºC, mientras que el tratamiento simple y combinado de UV-C indujo incrementos de un 440 %. Por consiguiente, el uso de UV-C, de alto interés como tratamiento sanitizante alternativo al cloro, combinado con la radiación UV-B no afectó negativamente la acumulación de compuestos bioactivos, consiguiendo aumentos similares a las muestras control (no tratadas). El cultivo del brócoli conlleva la producción de altas cantidades de subproductos, con el consiguiente impacto medioambiental, los cuales podrían ser usados como fuentes de compuestos beneficiosos para la salud por las industrias de alimentación y farmacéuticas. Además, estos subproductos de brócoli podrían ser revalorizados mediante el incremento de sus compuestos beneficiosos para la salud mediante radiación UV como estrés abiótico. En esta línea, se estudiaron los efectos de diferentes tratamientos de radiación UV-B (5, 10 and 15 kJ m-2), individual o combinados con una dosis de UV-C (9 kJ m-2), sobre los principales compuestos bioactivos de los subproductos del brócoli Bimi® (hojas y tallos) siendo comparados con las partes comestibles de este vegetal, los floretes. Las hojas mostraron TPC y TAC similares a los de los floretes con niveles de 1716 y 552 mg kg-1, respectivamente. Además, las hojas mostraron contenidos de glucorafanina/glucobrasicina 2,5/14,5 mayores que los floretes. Los tratamientos de UV incrementaron inicialmente los niveles de TPC y TAC de las muestras en un 30-97 y 20-424 %, respectivamente. Particularmente, el tratamiento UVB10+C indujo los mayores incrementos (110 %) de TPC en las hojas de Bimi® en las últimas 48 h de conservación mientras que UVB10 y UV10+C conllevaron a los niveles más altos de TPC (709 y 680 mg kg-1) en los tallos a las 48 h. Además, el tratamiento UV10+C indujo los mayores incrementos de glucobrasicina del 34 % mientras que UVB15 y UVB15+C produjeron los contenidos más altos de glucorafanina (131 y 117 mg kg-1) en los floretes después de 72 h. De esta forma, las hojas del brócoli Bimi® se muestran como un subproducto que puede ser utilizado como una fuente excelente de glucosinolatos y compuestos fenólicos (con alto poder antioxidante) para las industrias alimentarias y farmacéuticas. Además, el uso de tratamientos UV-B/C postcosecha combinados pueden revalorizar en gran medida estos subproductos agrícolas y también añadir valor a los floretes comestibles mínimamente procesados en fresco del brócoli Bimi®. Se estudió la calidad de un batido (smoothie) funcional obtenido de zanahoria rallada, previamente estresada (UV-C y/o alto oxígeno), tratado térmicamente (90 ºC durante 30 s), durante 14 días a 5 ºC. El smoothie tratado térmicamente mostró una buena calidad fisicoquímica y microbiológica (< 6 log unidades formadoras de colonias (CFU en inglés) g-1), tras los 14 días a 5 ºC. Sin embargo, en los smoothies que contenían zanahoria no irradiada se registraron recuentos más bajos de psicrófilos, mohos y levaduras. Los smoothies tratados térmicamente con zanahoria rallada no irradiada y almacenada en alto oxígeno mostraron los contenidos más altos de TPC con 13.8 mg de ácido clorogénico kg-1 tras 14 días at 5 ºC. En ese aspecto, la incubación previa de la zanahoria rallada en condiciones de hiperoxia permitió obtener un smoothie funcional con alto contenido de compuestos fenólicos, así como una buena calidad microbiológica y fisicoquímica tras 14 días a 5 ºC. La pasteurización fría de alimentos, como el procesado con alta presión (HPP en inglés), permite conseguir un producto con una mejor calidad nutricional, sin perder sus propiedades sensoriales, logrando también una vida útil más larga comparado con los tratamientos térmicos convencionales. De esta forma, se estudió la calidad fisicoquímica y microbiológica, y PAL/TPC de un smoothie naranja (con zanahoria y calabaza) tras diferentes tratamientos de HPP (control, 300-600 MPa durante 5 min a 23 ºC) y durante su conservación de 7 días a 5 ºC. En general, los parámetros de calidad no se vieron afectados por los tratamientos de HPP en comparación al control en el día de procesado ni tras 7 días a 5 ºC. HPP redujo los recuentos iniciales de mesófilos (3,4 log CFU mL-1) a 2,0-2,7 unidades logarítmicas, manteniéndolas durante los 7 días a 5 ºC, a diferencia de las muestras control. Los parámetros de calidad fisicoquímica de las muestras tratadas con HPP se mantuvieron durante la conservación. En general, los tratamientos de 300 y 600 MPa provocaron una mayor actividad de PAL tras 7 días a 5 ºC. Los TPC de los smoothies tratados con 300 y 400 MPa mostraron los mayores incrementos (1,6 veces) tras la conservación. La actividad de muchas enzimas alterantes de la calidad del producto puede aumentar debido a tratamientos de HPP de intensidad baja-intermedia en muchas bebidas. Por esta razón, en el siguiente experimento se contrarrestaron estos efectos debidos al HPP mediante la encapsulación con maltosil-β-ciclodextrina (90 mM) usando como modelo zumos de manzana debido a su rápido pardeamiento enzimático durante el procesado. La degradación del color del zumo de manzana durante 60 min a 22 ºC fue ajustada muy bien mediante un modelo de conversión fraccional con la raíz del error cuadrático medio (RMSE en inglés) inferior a 1,3. Los tratamientos de HPP (300-600 MPa durante 5 min a 22 ºC) no afectaron el efecto antipardeante de la maltosil-β-ciclodextrina. Por esta razón, la adición de maltosil-β-ciclodextrina en zumo de manzana, antes del tratamiento bajo-moderado de HPP (300 MPa durante 5 min a 22 ºC) puede controlar en gran medida el pardeamiento enzimático. En esta Tesis doctoral también se desarrolló por primera vez el concepto “listo para licuar” (ready-to-blend en inglés). De esta forma, se estudió la evolución de los parámetros de calidad de una mezcla de ensalada de cuarta gama de frutas y verduras ready-to-blend durante su conservación a 5 ºC. La vida útil del producto se extendió hasta 9 días mediante una película comestible de quitosano (10 g L-1) donde la actividad de la polifenoloxidasa y los niveles microbiológicos fueron muy bien controlados. Paralelamente se aumentó el valor añadido del producto mediante la fortificación con vitamina B12 (8.6 μg kg-1). Esta vitamina es de gran interés para diversos sectores de la población, tales como vegetarianos/veganos, personas mayores etc., debido a las necesidades especiales de la misma. El smoothie preparado posteriormente de la mezcla ready-to-blend mostró en general una buena calidad durante su conservación a 5 ºC durante 48 h. [ENG] Phenolic compounds are phytochemicals with high health-promoting properties which are present in several fruit and vegetables such as carrots and broccoli. Carrot is a worldwide highly consumed vegetable although its phenolic content is relatively low regarding other horticultural products. Accordingly, the enhancement of phenolic levels in carrots, using i.e. abiotic stresses, will add value to this popular vegetable for the food and pharmaceutical industries. Chlorogenic acid represented 70 % of the sum of phenolic compounds in carrots. Total phenolic contents (TPC) of carrots during storage periods were highly correlated (R2=0.82) to total antioxidant capacity (TAC) of these samples. It was found that shredding (wounding stress) and hyperoxia storage (80 kPa O2) induced the highest phenylalanine ammonia-lyase (PAL), TPC and TAC enhancements in carrots during storage at 15 ºC for 72 h. Although pretreatment of shreds with an intermediate UV-C dose (9 kJ m-2) reduced phenolic accumulation, 600 % increments were still registered in those samples stored under hyperoxia conditions for 72 h. These first findings of the PhD Thesis supply to the food and pharmaceutical industries useful and sustainable tools to obtain a great source of health-promoting compounds from this vegetable, and probable to others. Subsequently, the effect of UV-B pretreatment (1.5 kJ m-2) was studied on the PAL/TPC/TAC of shredded carrots and its combination with a low-intermediate (4 kJ m-2) UV-C dose. UV-B treatment induced the highest PAL/TPC of 760/498 % after 72 h at 15 ºC, regarding their initial levels, while single and combined UV-C treatments induced a TPC accumulation of 440 %. Accordingly, the use of UV-C treatment, with high sanitizing interest for the fresh-cut industry, combined with UV-B radiation did not negatively affect the accumulation of bioactive compounds, achieving similar enhancements to untreated samples. Broccoli cultivation leads to high volumes of plant by-products with high environmental impact which may be instead used as sources of health-promoting compounds for the food and pharmaceutical industries. Furthermore, such broccoli by-products may be revalorized through the increase of their health-promoting compounds with postharvest UV radiation as an abiotic stress. Accordingly, the effects of different postharvest UV-B radiation doses (5, 10 and 15 kJ m-2), single or combined with UV-C treatment (9 kJ m- 2), were studied on the main bioactive compounds of Bimi® broccoli by-products (leaves and stalks) being compared to Bimi® edible florets. Leaves showed similar TPC and TAC, with 1716 and 552 mg kg-1 respectively, compared to florets. Furthermore, leaves showed 2.5/14.5 higher glucoraphanin/glucobrassicin contents than florets. UV postharvest treatments initially increased TPC and TAC levels of samples by 30-97 and 20-424 %, respectively. Particularly, UVB10+C treatment induced the highest TPC increase (110 %) in Bimi® leaves in the last 48 h of storage while UVB10 and UV10+C led to the highest TPC (709 and 680 mg kg-1) of stalks at 48 h. Furthermore, UV10+C treatment increased glucobrassicin levels of leaves by 34 % while UVB15 and UVB15+C induced the highest glucoraphanin levels (131 and 117 mg kg-1) in florets after 72 h. Accordingly, Bimi® leaves are hereby presented as a by-product that may be used as an excellent source of glucosinolates and phenolics, with high total antioxidant capacity, for the food and pharmaceutical industries. In addition, postharvest intermediate-high UV-B/C combined radiation treatments can highly revalorize such agricultural by-products and also add value to the edible fresh-cut Bimi® florets. A functional smoothie containing the previously stressed (UV-C and/or high O2) carrot shreds with high TPC/TAC contents was thermally treated (90 ºC for 30 s) and the beverage quality was studied during 14 days at 5 ºC being compared to CTRL samples. Heat-treated smoothies showed a good physicochemical and microbiological quality (< 6 log CFU g-1) after 14 days at 5 ºC, although smoothies containing non-irradiated shreds registered lower psychrophilic and yeasts and moulds levels. Heat-treated smoothie containing non-irradiated O2-shreds showed the highest TPC of 13.8 mg kg-1 after 14 days at 5 ºC. In this sense, a pre-enrichment incubation of carrot shreds under hyperoxia conditions allowed to obtain a functional smoothie with high phenolic levels and good microbiological and physicochemical quality up to 14 days at 5 ºC. A non-thermal treatment, such as high pressure processing (HPP), of beverages may allow to obtain a product with better bioactive/nutritional and sensory quality, and extended shelf life regarding thermally treated samples. Accordingly, the physicochemical and microbial quality, and PAL/TPC of an orange smoothie (carrot and pumpkin) after different HPP treatments (CTRL, 300-600 MPa for 5 min at 23 ºC) and during storage for 7 days at 5ºC were studied. In general, quality parameters did not highly change after HPP treatments compared to CTRL samples on the processing day and after 7 days at 5 ºC. HPP reduced initial mesophilic counts (3.4 log CFU mL-1) by 2.0-2.7 log units being these microbial counts well maintained after 7 days at 5 ºC contrary to CTRL samples. The physicochemical quality of the HPP-treated smoothies was highly maintained during storage. Generally, the 300 and 600 MPa HPP treatments induced the highest PAL activities after 7 days at 5 ºC. The initial TPC (712.1 mg ChAE kg-1) was increased in the smoothies reaching the 300 and 400 MPa-treated samples the highest increments (1.6-fold) after storage. The activity of some quality-degradative enzymes may be increased in determined beverages under low-moderate HPP treatments. For that reason, in the next study we tried to palliate such undesirable HPP effects by encapsulation with maltosyl-β-cyclodextrin (90 mM) using apple juice as beverage model due to the rapid enzymatic browning during processing of this fruit juice. Colour degradation of apple juice during 60 min at 22 ºC was well fitted to a fractional conversion model with root-mean-square error (RMSE) < 1.3. HPP treatments (300-600 MPa for 5 min at 22 ºC) did not affect the antibrowning effect of maltosyl-β-cyclodextrin. In that sense, maltosyl-β-cyclodextrin addition to apple juice prior to a low-moderate HPP treatment (300 MPa for 5 min at 22 ºC) highly controlled enzymatic browning. A new food concept ‘ready-to-blend’ was firstly developed and studied in this PhD Thesis. Accordingly, the quality of a fresh-cut fruit/vegetables ‘ready-to-blend’ product was studied during storage at 5 ºC. The shelf life of the ready-to-blend product was highly extended to 9 days by a chitosan coating (10 g L-1) being microbial levels and polyphenoloxidase activity well controlled. Added value of the product was enhanced by fortification with vitamin B12 (8.6 μg kg-1) being of high interest for specific population sectors, such as vegetarians/vegans, elderly, etc., which have special needs for this vitamin. The prepared smoothies from the ready-to-blend portion showed a good quality during subsequent storage for 48 h at 5 ºC.Escuela Internacional de DoctoradoUniversidad Politécnica de CartagenaPrograma de Doctorado Técnicas Avanzadas en Investigación y Desarrollo Agrario y Alimentari

Package on actions for damages based on breaches of EU competition rules: Can one size fit all?

On 17 April 2014, the Proposal for a Directive on antitrust damages actions was accepted by the European Parliament and sent to the EU Council of Ministers for final approval. In addition, a Recommendation was adopted in 2013 on common principles for injunctive and compensatory collective redress mechanisms in the Member States to meet the need for a coherent European approach to antitrust private enforcement. This package comes at a time when private antitrust enforcement is rapidly evolving in a number of Member States. At the same time however, it establishes several legal solutions that do not fit well with existin

Entrepreneurship and Creative Economy: Mental Models of Cultural Entrepreneurs in Belo Horizonte, Brazil

This study aims to analyze the common elements in the mental models of cultural entrepreneurs in Belo Horizonte, Brazil, as well as to contribute to the expansion of public policies that enable the development of such enterprises. The theoretical framework of this study addresses entrepreneurship and the mental models of entrepreneurs in the creative economy sector. The Brazilian government has showed concern with the development of the creative economy sector, considering its importance in the national and international scenario. There is a lack of information and data that describes the specific characteristics and issues of the creative economy. Thus, it is important not only to present a statistical data on the sector, but also qualitative data that can broaden and deepen the knowledge of the sector and its professionals

Herpes Simplex Virus Type 1/Adeno-Associated Virus Hybrid Vectors

Herpes simplex virus type 1 (HSV-1) amplicons can accommodate foreign DNA of any size up to 150 kbp and, therefore, allow extensive combinations of genetic elements. Genomic sequences as well as cDNA, large transcriptional regulatory sequences for cell type-specific expression, multiple transgenes, and genetic elements from other viruses to create hybrid vectors may be inserted in a modular fashion. Hybrid amplicons use genetic elements from HSV-1 that allow replication and packaging of the vector DNA into HSV-1 virions, and genetic elements from other viruses that either direct integration of transgene sequences into the host genome or allow episomal maintenance of the vector. Thus, the advantages of the HSV-1 amplicon system, including large transgene capacity, broad host range, strong nuclear localization, and availability of helper virus-free packaging systems are retained and combined with those of heterologous viral elements that confer genetic stability to the vector DNA. Adeno-associated virus (AAV) has the unique capability of integrating its genome into a specific site, designated AAVS1, on human chromosome 19. The AAV rep gene and the inverted terminal repeats (ITRs) that flank the AAV genome are sufficient for this process. HSV-1 amplicons have thus been designed that contain the rep gene and a transgene cassette flanked by AAV ITRs. These HSV/AAV hybrid vectors direct site-specific integration of transgene sequences into AAVS1 and support long-term transgene expression

Urban environment cues for health and well-being in the elderly

Urban populations are increasing at a rate that challenges existing public health infrastructures, while contemporary literature proliferates in the attempt to identify links between city neighbourhoods and health and well-being. Despite this, there have been few attempts to synthesize research into neighbourhood features perceived by elderly residents to affect their health and well-being. The primary objective of this review is to establish whether and, if so, how the perception of urban environment features acts as health and well-being determinants in an ageing population. Data extracted from 49 eligible articles into five key neighbourhood domains and thematic analysis show that poor health and reduced activity are associated with negatively perceived environments. In addition, urban social cohesion, crime and safety influences activity choices. Higher activity is associated with more compact and varied land-use mix with appealing aesthetics. Isolating individual perceived neighbourhood features as directly associated health determinants among the elderly is complex due to inter-relations and overlap between domains. Identification of perceived environment health and well-being barriers or facilitators by the elderly are under-represented and warrants further investigation. Participatory objective and subjective research will contribute towards a more robust evidence base for public health professionals and policymakers by identifying knowledge gaps

Historicidade e historiografia: contribuição da entrevista fenomenológica para a Enfermagem

Estudio cualitativo fundamentado en la fenomenología con el fin de mostrar la historiografía y Historicidad como posibilidades analíticas de la entrevista basada en lo referencial teórico y metodológico del Martin Heidegger. Escenario fue a un hospital de Minas Gerais y como deponentes diez mujeres significado que significaban sus entendimientos sobre el día a día después de la cirugía cardíaca a través de la entrevista fenomenológica. Se utilizó la analítica hermenéutica heideggeriana. Los resultados mostraron que la construcción de la historiografía y la historicidad de inauguración movimiento del ser-mujer-después de la cirugía cardíaca, lo que permite al investigador a entender una forma que favorece la intersubjetividad. Consideramos que la extensión de esta investigación a la práctica médica, que en este estudio se dirige a la salud de la mujer, ya que la intersubjetividad puede ayudar a los profesionales de la salud de guía para conocer el Ser, moviendo el balón óntico ontológica al rescate atención-con el otro de sus múltiples y únicos necesidades.Qualitative study grounded in phenomenology in order to highlight the historiography and historicity as an analytical possibilities of the interview based on the theoretical and methodological referential of Martin Heidegger. Scenario was to a hospital in Minas Gerais and as deponents ten women that denoted their understandings about the day to day after cardiac surgery through Phenomenological Interview. It was used the Heideggerian analytical hermeneutics. The results showed the construction of historiography and historicity in motion unveiling of being-there-woman-after-cardiac-surgery, allowing the researcher to understand a way that favors intersubjectivity. We consider the extension of this research to healthcare practice, which in this study turns to women’s health, since intersubjectivity may help guide health professionals to meet the Being, moving the ball ontic ontological to the rescue care-with each other from their multiple and unique needs.Estudo qualitativo ancorado na fenomenologia com o objetivo de evidenciar a historiografia e a historicidade como posibilidades decorrentes do movimento de análise da entrevista fenomenológica fundada no referencial teórico-metodológico de Martin Heidegger. Teve como cenário uma instituição hospitalar em Minas Gerais e como depoentes dez mulheres que significaram suas compreensões acerca do dia a dia após uma cirurgia cardíaca por meio da Entrevista Fenomenológica. Utilizou-se a analítica hermenêutica Heideggeriana. Os resultados apontam a construção da historiografia e da historicidade no movimento de desvelamento do ser-aí-mulher-após-cirurgia-cardíaca, possibilitando ao pesquisador a compreensão de um caminho que favorece a intersubjetividade. Considera-se a extensão desta investigação à prática assistencial, uma vez que a intersubjetividade pode balizar o profissional de saúde ao encontro do Ser, movimentando-se da esfera ôntica à ontológica no resgate do cuidado-com o outro a partir de suas múltiplas e singulares necessidades

Band widths and gaps from the Tran-Blaha functional : Comparison with many-body perturbation theory

For a set of ten crystalline materials (oxides and semiconductors), we compute the electronic band structures using the Tran-Blaha [Phys. Rev. Lett. 102, 226401 (2009)] (TB09) functional. The band widths and gaps are compared with those from the local-density approximation (LDA) functional, many-body perturbation theory (MBPT), and experiments. At the density-functional theory (DFT) level, TB09 leads to band gaps in much better agreement with experiments than LDA. However, we observe that it globally underestimates, often strongly, the valence (and conduction) band widths (more than LDA). MBPT corrections are calculated starting from both LDA and TB09 eigenenergies and wavefunctions. They lead to a much better agreement with experimental data for band widths. The band gaps obtained starting from TB09 are close to those from quasi-particle self-consistent GW calculations, at a much reduced cost. Finally, we explore the possibility to tune one of the semi-empirical parameters of the TB09 functional in order to obtain simultaneously better band gaps and widths. We find that these requirements are conflicting.Comment: 18 pages, 16 figure

Attacks by “Anonymous” WikiLeaks Proponents not Anonymous

On November 28, 2010, the world started watching the whistle blower website WikiLeaks to begin publishing part of the 250,000 US Embassy Diplomatic cables. These confidential cables provide an insight on U.S. international affairs from 274 different embassies, covering topics such as analysis of host countries and leaders and even requests for spying out United Nations leaders.\ud The release of these cables has caused reactions not only in the real world, but also on the Internet. In fact, a cyberwar started just before the initial release. Wikileaks has reported that their servers were experiencing distributed denial-of-service attacks (DDoS). A DDoS attack consists of many computers trying to overload a server by firing a high number of requests, leading ultimately to service disruption. In this case, the goal was to avoid the release of the embassy cables.\ud After the initial cable release, several companies started severed ties with WikiLeaks. One of the first was Amazon.com, that removed the WikiLeaks web- site from their servers. Next, EveryDNS, a company in which the domain wikileaks.org was registered, dropped the domain entries from its servers. On December 4th, PayPal cancelled the account that WikiLeaks was using to receive on-line donations. On the 6th, Swiss bank PostFinance froze the WikiLeaks assets and Mastercard stopped receiving payments to the WikiLeaks account. Visa followed Mastercard on December 7th.\ud These reactions caused a group of Internet activists (or “hacktivists”) named Anonymous to start a retaliation against PostFinance, PayPay, MasterCard, Visa, Moneybrookers.com and Amazon.com, named “Operation Payback”. The retaliation was performed as DDoS attacks to the websites of those companies, disrupting their activities (except for the case of Amazon.com) for different periods of time.\ud The Anonymous group consists of volunteers that use a stress testing tool to perform the attacks. This tool, named LOIC (Low Orbit Ion Cannon), can be found both as a desktop application and as a Web page.\ud Even though the group behind the attacks claims to be anonymous, the tools they provide do not offer any security services, such as anonymization. As a consequence, a hacktivist that volunteers to take part in such attacks, can be traced back easily. This is the case for both current versions of the LOIC tool. Therefore, the goal of this report is to present an analysis of privacy issues in the context of these attacks, and raise awareness on the risks of taking part in them

Towards Bandwidth Estimation Using Flow-Level Measurements

Bandwidth estimation is one of the prerequisite for efficient link dimensioning. In the past, several approaches to bandwidth estimation have been proposed, ranging from rules-of-thumb providing over-provisioning guidelines to mathematically backed-up provisioning formulas. The limitation of such approaches, in our eyes, is that they largely rely on packet-based measurements, which are almost unfeasible considering nowadays load and speed (1–10 Gbps). In this context, flow-based measurements seems to be a suitable alternative, addressing both data aggregation as well as scalability issues. However, flows pose a challenge for bandwidth estimation, namely the coarser data granularity compared to packet-based approaches, which can lead to a lower precision in the estimation of the needed bandwidth. In this paper, we investigate what is the impact of flow-based measurements on bandwidth estimation. In particular, we are interested in quantifying the impact of flows on main statistical traffic characteristics, in particular the traffic rate variance. Our approach is validated on real traffic traces captured from 2002 to 2011 at the University of Twente