The Trapping and Characterization of a Single Hydrogen Molecule in a Continuously Tunable Nanocavity

Using inelastic electron tunneling spectroscopy with the scanning tunneling microscope (STM-IETS) and density functional theory calculations (DFT), we investigated properties of a single H2 molecule trapped in nanocavities with controlled shape and separation between the STM tip and the Au (110) surface. The STM tip not only serves for the purpose of characterization, but also is directly involved in modification of chemical environment of molecule. The bond length of H2 expands in the atop cavity, with a tendency of dissociation when the gap closes, whereas it remains unchanged in the trough cavity. The availability of two substantially different cavities in the same setup allows understanding of H2 adsorption on noble metal surfaces and sets a path for manipulating a single chemical bond by design.Comment: 11 pages, 4 figure

Modelling Acceleration Decisions in Traffic Streams with Weak Lane Discipline: A Latent Leader Approach

Acceleration is an important driving manoeuvre that has been modelled for decades as a critical element of the microscopic traffic simulation tools. The state-of-the art acceleration models have however primarily focused on lane based traffic. In lane based traffic, every driver has a single distinct lead vehicle in the front and the acceleration of the driver is typically modelled as a function of the relative speed, position and/or type of the corresponding leader. On the contrary, in a traffic stream with weak lane discipline, the subject driver may have multiple vehicles in the front. The subject driver is therefore subjected to multiple sources of stimulus for acceleration and reacts to the stimulus from the governing leader. However, only the applied accelerations are observed in the trajectory data, and the governing leader is unobserved or latent. The state-of-the-art models therefore cannot be directly applied to traffic streams with weak lane discipline. This prompts the current research where we present a latent leader acceleration model. The model has two components: a random utility based dynamic class membership model (latent leader component) and a class-specific acceleration model (acceleration component). The parameters of the model have been calibrated using detailed trajectory data collected from Dhaka, Bangladesh. Results indicate that the probability of a given front vehicle of being the governing leader can depend on the type of the lead vehicle and the extent of lateral overlap with the subject driver. The estimation results are compared against a simpler acceleration model (where the leader is determined deterministically) and a significant improvement in the goodness-of-fit is observed. The proposed models, when implemented in microscopic traffic simulation tools, are expected to result more realistic representation of traffic streams with weak lane discipline

Reporting on health-related research in two prestigious Brazilian newspapers

OBJECTIVES: The dissemination of health-related news through newspapers can influence the behavior of patients and of health care providers. We conducted a study to analyze the characteristics of health-related research published by two leading Brazilian newspapers. METHOD: We retrospectively evaluated health-related news published in the electronic versions of the newspapers Folha de São Paulo and O Estado de São Paulo over a period of three months (July through September, 2009). Only articles mentioning medical research were included. The articles were categorized according to topic, source, study location and the nature of the headline. We also analyzed the presence of background information on the topic, citations of medical periodicals, national contextualization and references to products or companies. RESULTS: Scientific research articles corresponded to 57% and 20% of health-related articles published by Folha de São Paulo and O Estado de São Paulo, respectively. Folha de São Paulo published significantly more articles about national studies, and most articles were written by its own staff. In contrast, most articles in O Estado de São Paulo came from news agencies. Folha de São Paulo also better contextualized its reports for Brazilian society. O Estado de São Paulo tended to cite the name of the periodical in which the study was published more frequently, but their articles lacked national contextualization. CONCLUSION: The results showed a significant difference in the way in which the studied newspapers report on health-related research. Folha de São Paulo tends to write its own articles and more frequently publishes the results of national research, whereas O Estado de São Paulo publishes articles that originate in news agencies, most of which have little national contextualization

Reporting on health-related research in two prestigious Brazilian newspapers

OBJECTIVES: The dissemination of health-related news through newspapers can influence the behavior of patients and of health care providers. We conducted a study to analyze the characteristics of health-related research published by two leading Brazilian newspapers. METHOD: We retrospectively evaluated health-related news published in the electronic versions of the newspapers Folha de São Paulo and O Estado de São Paulo over a period of three months (July through September, 2009). Only articles mentioning medical research were included. The articles were categorized according to topic, source, study location and the nature of the headline. We also analyzed the presence of background information on the topic, citations of medical periodicals, national contextualization and references to products or companies. RESULTS: Scientific research articles corresponded to 57% and 20% of health-related articles published by Folha de São Paulo and O Estado de São Paulo, respectively. Folha de São Paulo published significantly more articles about national studies, and most articles were written by its own staff. In contrast, most articles in O Estado de São Paulo came from news agencies. Folha de São Paulo also better contextualized its reports for Brazilian society. O Estado de São Paulo tended to cite the name of the periodical in which the study was published more frequently, but their articles lacked national contextualization. CONCLUSION: The results showed a significant difference in the way in which the studied newspapers report on health-related research. Folha de São Paulo tends to write its own articles and more frequently publishes the results of national research, whereas O Estado de São Paulo publishes articles that originate in news agencies, most of which have little national contextualization

Modeling reaction time within a traffic simulation model

Human reaction time has a substantial effect on modeling of human behavior at a microscopic level. Drivers and pedestrian do not react to an event instantaneously; rather, they take time to perceive the event, process the information, decide on a response and finally enact their decision. All these processes introduce delay. As human movement is simulated at increasingly fine-grained resolutions, it becomes critical to consider the delay due to reaction time if one is to achieve accurate results. Most existing simulators over-simplify the reaction time implementation to reduce computational overhead and memory requirements. In this paper, we detail the framework which we are developing within the SimMobility Short Term Simulator (a microscopic traffic simulator), which is capable of explicitly modeling reaction time for each person in a detailed, flexible manner. This framework will enable modelers to set realistic reaction time values, relying on the simulator to handle implementation and optimization considerations. Following this, we report our findings demonstrating the impact of reaction time on traffic dynamics within several simulation scenarios. The findings indicate that in the incorporation of reaction time within microscopic simulations improves the traffic dynamics that produces more realistic traffic condition.Singapore-MIT Alliance for Research and Technolog

Modeling the strangeness content of hadronic matter

The strangeness content of hadronic matter is studied in a string-flip model that reproduces various aspects of the QCD-inspired phenomenology, such as quark clustering at low density and color deconfinement at high density, while avoiding long range van der Waals forces. Hadronic matter is modeled in terms of its quark constituents by taking into account its internal flavor (u,d,s) and color (red, blue, green) degrees of freedom. Variational Monte-Carlo simulations in three spatial dimensions are performed for the ground-state energy of the system. The onset of the transition to strange matter is found to be influenced by weak, yet not negligible, clustering correlations. The phase diagram of the system displays an interesting structure containing both continuous and discontinuous phase transitions. Strange matter is found to be absolutely stable in the model.Comment: 14 pages, 1 table, 8 eps figures, revtex. Submitted to Phys. Rev. C, Presented at INPC2001 Berkeley, Ca. july 29-Aug

Energy efficiency and quality of service optimization for constant bit rate real-time applications in 802.11 networks

In this paper, we propose a quality of service (QoS)‐sensitive energy efficiency optimization mechanism for 802.11 networks on the basis of the dynamic and simultaneous adjustment of the content window (W) and retry attempts limit (r) of the media access control (MAC) sublayer. The use of both operational variables let us not only find the optimum operational point regarding energy efficiency but also attain a positive impact on the QoS, which improves the results obtained with current single‐variable optimization strategies. The model under consideration includes external noise and does not impose the saturation condition in stations and as such is well suited for real‐time industrial applications under noisy channels. Results obtained from simulation confirm the advantages of adjusting simultaneously W and r versus adjusting either one separately, obtaining a slight improvement in energy efficiency and resulting in less loss and delay at the MAC sublayer.Unión Europea FP7‐223866Ministerio de Ciencia e Innovación DPI2010‐1915Ministerio de Ciencia e Innovación TEC2010‐20861Junta de Andalucía TIC‐633

Locating farmer-based knowledge and vested interests in natural resource management: the interface of ethnopedology, land tenure and gender in soil erosion management in the Manupali watershed, Philippines

This paper examines local soil knowledge and management in the Manupali watershed in the Philippines