Search for a Higgs Boson Decaying into Two Photons with the L3 Detector at LEP

A search is performed for a Higgs boson, decaying into two photons, using the L3 data collected at centre of mass energies between $\sqrt s$ = 189 and 202 GeV, corresponding to an integrated luminosity of 400 pb$^{-1}$. The processes $e^{+}e^{-}\to {Zh} \to {q} \bar{q} \gamma \gamma$, $e^{+}e^{-}\to {Zh} \to \nu \bar{\nu} \gamma \gamma$, $e^{+}e^{-}\to {Zh} \to {l}^{+} {l}^{-} \gamma \gamma$ are considered. The observed data are found to be consistent with the expected background from standard physics processes. Limits on the branching fraction of the Higgs boson decay into two photons as a function of the Higgs mass are shown and a lower mass limit on a fermiophobic Higgs is derived.Comment: 3 pages, 2 postscript figures, Presented at the DPF2000 Conference, August 9-12, 2000, The Ohio State University, Columbus, Ohi

Key exchange with the help of a public ledger

Blockchains and other public ledger structures promise a new way to create globally consistent event logs and other records. We make use of this consistency property to detect and prevent man-in-the-middle attacks in a key exchange such as Diffie-Hellman or ECDH. Essentially, the MitM attack creates an inconsistency in the world views of the two honest parties, and they can detect it with the help of the ledger. Thus, there is no need for prior knowledge or trusted third parties apart from the distributed ledger. To prevent impersonation attacks, we require user interaction. It appears that, in some applications, the required user interaction is reduced in comparison to other user-assisted key-exchange protocols

Understory plant communities show resistance to drought, hurricanes, and experimental warming in a wet tropical forest

Global climate change has led to rising temperatures and to more frequent and intense climatic events, such as storms and droughts. Changes in climate and disturbance regimes can have non-additive effects on plant communities and result in complicated legacies we have yet to understand. This is especially true for tropical forests, which play a significant role in regulating global climate. We used understory vegetation data from the Tropical Responses to Altered Climate Experiment (TRACE) in Puerto Rico to evaluate how plant communities responded to climate warming and disturbance. The TRACE understory vegetation was exposed to a severe drought (2015), 2 years of experimental warming (4°C above ambient in half of the plots, 2016–2017 and 2018–2019), and two major hurricanes (Irma and María, September 2017). Woody seedlings and saplings were censused yearly from 2015 to 2019, with an additional census in 2015 after the drought ended. We evaluated disturbance-driven changes in species richness, diversity, and composition across ontogeny. We then used Bayesian predictive trait modeling to assess how species responded to disturbance and how this might influence the functional structure of the plant community. Our results show decreased seedling richness after hurricane disturbance, as well as increased sapling richness and diversity after warming. We found a shift in species composition through time for both seedlings and saplings, yet the individual effects of each disturbance were not significant. At both ontogenetic stages, we observed about twice as many species responding to experimental warming as those responding to drought and hurricanes. Predicted changes in functional structure point to disturbance-driven functional shifts toward a mixture of fast-growing and drought-tolerant species. Our findings demonstrate that the tropical forest understory community is more resistant to climatic stressors than expected, especially at the sapling stage. However, early signs of changes in species composition suggest that, in a warming climate with frequent droughts and hurricanes, plant communities might shift over time toward fast-growing or drought-tolerant species

HIV Infection among Young People in Northwest Tanzania: The Role of Biological, Behavioural and Socio-Demographic Risk Factors.

BACKGROUND: Young people are at high risk of HIV and developing appropriate prevention programmes requires an understanding of the risk factors for HIV in this age group. We investigated factors associated with HIV among participants aged 15-30 years in a 2007-8 cross-sectional survey nested within a community-randomised trial of the MEMA kwa Vijana intervention in 20 rural communities in northwest Tanzania. METHODS: We analysed data for 7259(53%) males and 6476(47%) females. Using a proximate-determinant conceptual framework and conditional logistic regression, we obtained sex-specific Odds Ratios (ORs) for the association of HIV infection with socio-demographic, knowledge, behavioural and biological factors. RESULTS: HSV-2 infection was strongly associated with HIV infection (females: adjOR 4.4, 95%CI 3.2-6.1; males: adjOR 4.2, 95%CI 2.8-6.2). Several socio-demographic factors (such as age, marital status and mobility), behavioural factors (condom use, number and type of sexual partnerships) and biological factors (blood transfusion, lifetime pregnancies, genital ulcers, Neisseria gonorrhoeae) were also associated with HIV infection. Among females, lifetime sexual partners (linear trend, p<0.001), ≥2 partners in the past year (adjOR 2.0, 95%CI 1.4-2.8), ≥2 new partners in the past year (adjOR 1.9 95%CI 1.2, 3.3) and concurrent partners in the past year (adjOR 1.6 95%CI 1.1, 2.4) were all associated with HIV infection. CONCLUSIONS: Efforts must be intensified to find effective interventions to reduce HSV-2. Effective behavioural interventions focusing on reducing the number of sexual partnerships and risk behaviour within partnerships are also needed. An increase in risky sexual behaviour may occur following marriage dissolution or when a young woman travels outside of her community and interventions addressing the needs of these subgroups of vulnerable women may be important. TRIAL REGISTRATION: ClinicalTrial.gov NCT00248469

Tratamiento de agua residual de microbiología usando películas delgadas de TiO2

(Eng) Microbiology cell-staining wastewater was treated by UV/TiO 2 thin films photocatalysis. A simple method of applying gravity sedimentation over grass-type substrate was used for the preparation of the films. The use of Na4 P2 O7, microwaves, and ultrasounds were studied for decreasing the TiO2 grain sizes on the films. It was established that the best method for reducing grain size resulted from a combination of Na4P2O7 (0.01M) and microwave radiation (700 W, 20 min). The Films were characterized by several microscopic and spectroscopic methods. Anatase phase (gap energy of 3.2 eV) and grain sizes averaging 83 nm were achieved. Photocatalysis tests using TiO2-film showed 99.5 % of decolorization, 79 % TOC abatement, and total microbial inactivation after 14 h of treatment. No bacteria re–growth was found 48 h after the treatment was completed.(Spa) La fotocatálisis con UV/TiO2usando películas delgadas fue empleada para el tratamiento de agua residual de microbiología. Se empleó un método simple de sedimentación por gravedad sobre sustrato de vidrio para la preparación de las películas. El uso de Na4P2O7, microondas y ultrasonido fue estudiado para la disminución de los granos de TiO2 en las películas. Se estableció que el mejor método para disminuir los agregados resultó de una combinación de Na4P2O7(0.01M) y radiación de microondas (700 W, 20 min). Las películas fueron caracterizadas por métodos microscópicos y espectroscópicos. Se obtuvo la fase anatasa (brecha de energía de 3.2 e.V) y tamaños de grano de 83nm. Los ensayos fotocatalíticos utilizando las películas de TiO2generaron un 99.5% de decoloración, 79% de remoción de COT y una inactivación microbiana total luego de 14 h de tratamiento. No se encontró reactivación microbiana luego de 48 h de finalizado el tratamiento

A cross-cultural, participatory approach for measuring and cultivating resilience on small and medium farms

One of the greatest leverage points in fostering the transition to sustainability can be found in the realm of food systems. The COVID-19 pandemic has brought into sharp focus the critical importance of small farm resilience to the well-being of communities around the world. We explored the role of small and medium farms in promoting sustainable social-agricultural systems, and investigated how the resilience of these farms can be both measured and amplified. W e integrated concepts from the fields of food systems sustainability and resilience, agroecology, and positive deviance to identify indicators that can help measure and track farm resilience. Our aims were to 1) investigate the diversity of ecological and social factors that impact the vulnerability, resilience, and long-term health of small-medium farms and farm systems, exploring similarities and differences between the two cultures/geographies; 2) incorporate farmers’ personal experiences together with knowledge in the academic literature to enrich understanding about food systems sustainability; and 3) develop an indicator tool for evaluating farm resilience that empowers farmers to both assess their local farm system and to implement and document change over time. Our research process employed a cross-cultural, mixed-methods, Participatory Action Research (PAR) approach that engaged farmers from diverse geographic settings in Puerto Rico and Vermont. The project was organized into four phases implemented over a six month period from July through December 2020. These included identifying farmer participants, selecting key farm resilience frameworks, distilling a preliminary list of indicators, and validating those indicators with farmer feedback through surveys, interviews, and group meetings. The phases culminated in the creation of a Farm Resilience Tool for conducting rapid assessments using 20 indicators organized into four categories of Growth Mindset, Strong Relationships, Sustainable Farming Practices, and Sustainable Business Management. We further outlined a proposal for how to implement and refine the tool with farmer participants through subsequent PAR activities. Refinement is essential, given that our proposal is place-based and local, yet also modular and globally scalable to help advance planetary sustainability. More research is necessary to understand potential tradeoffs and synergies that can occur from trying to optimize multiple outcomes in tandem, and how to transition small farm resilience to broader-scale landscape planning and management strategies. Among the important lessons learned from this project are A) the importance of farmer-to-farmer knowledge sharing, B) the value of an authentic and reciprocal PAR process in expanding the range and depth of understanding beyond the academic literature, C) the utility of integrating positive deviants for helping identify indicators and examples of resilience outside the box of traditional thinking, and D) the rich interaction across cultures and geographies that enlivens the research and enlightens the outcomes. All these lessons converge on the critical insight that sustainability is ultimately about the quality of relationships within food systems. Thus, food systems research must integrate objective and subjective methods in order to cultivate the relational synergy needed to address and transcend the complex problems we face in the 21st Century