National occupational research agenda (NORA) future directions in occupational musculoskeletal disorder health research

Musculoskeletal disorders are among the most costly health care problems facing society today. The scientific literature has indicated that psychosocial factors, individual factors, workplace physical requirements, and workplace organizational factors have been associated with risk. Since musculoskeletal risk is multi-dimensional, the magnitude of risk attributable to various factors can be of importance to scientists and policy makers in designing countermeasures to reduce injury incidence. Traditionally, the disciplines of biomechanics, physiology, and psychophysics have dominated the body of knowledge that has defined exposure limitations to work. However, recent research has explored the association of psychosocial and work organization factors with musculoskeletal problems. Advances have been made to better quantify the levels of occupational exposure by improved exposure metrics, quantification of three-dimensional loads experienced by certain joints (e.g. the spine), identification of tissue tolerance limits and tissue response to mechanical stresses, and the impact of psychosocial stresses. However, efforts to quantitatively link epidemiological, biomechanical loading, soft tissue tolerance, and psychosocial studies should be pursued to establish a better understanding of the pathways of injury and resultant preventive strategies. Although we are beginning to understand how the major risk factors influence the load-tolerance relationship of human tissue, how these risk factors interact is virtually unexplored. Since the impact of the interactions may be far greater than that of any individual factor, the impact of the interactions between risk factors must be delineated so that work-related risk can be better quantified. Efforts to quantitatively link epidemiological, biomechanical loading, soft tissue tolerance, and psychosocial studies should be pursued to establish a better understanding of the pathways of injury and resultant preventive strategies.     

Guarding against online threats: why entrepreneurs take protective measures

Information technology is becoming increasingly important for entrepreneurs. Protecting their technical infrastructure and stored data is, therefore, also becoming more vital. Nevertheless, research into the safety and security of entrepreneurs in general, and online threats targeted at entrepreneurs in particular, is still limited. This study investigates to what extent self-employed entrepreneurs protect themselves against online threats, and what motivates them to do so. Based on secondary analyses on data collected from 1622 Dutch entrepreneurs, we observe that the majority implement technical and personal coping measures. By adopting protection motivation theory as a theoretical basis for our study, we found that coping appraisal explains the adoption of protective measures. Entrepreneurs are likely to implement protective measures when they believe a measure is effective, when they are capable of using internet technology, when their attitude towards online protection is positive and when they believe they are responsible for their own online security. Although the secondary analysis provides some limitations, this study offers new insights into the usage of protective measures and the motivation for taking them. These insights can help to improve information security campaigns.     

Going Beyond Telecenters to Foster the Digital Inclusion of Older People in Brazil: Lessons Learned from a Rapid Ethnographical Study

Telecenters take on a prominent role within the current information and communications technology (ICT) ecosystem in Brazil. They are seen by a great many as a key means to foster the digital inclusion of the older population in the country. This paper draws upon a rapid ethnographic study conducted with 78 older people in a center that teaches computer classes to seniors in Brazil. The results show that providing older people with technological infrastructures is not enough to strengthen their digital inclusion if their basic and non-instrumental needs are not taken into consideration in defining educational activities to be carried out in public centers. Participants’ basic needs when it comes to interacting with ICT, such as coping with accessibility issues, were dynamic, whilst non-instrumental needs, fulfilled by using these technologies, such as interacting with relevant others, remained fairly constant throughout the study. Drawing on the results of the study, strategies for fostering the digital inclusion and well-being of older people in Brazil that go beyond telecenters are suggested.     

On benefits and drawbacks of aging strategies for randomized search heuristics

Quite different search heuristics make use of the concept of assigning an age to search points and systematically remove search points that are too old from the search process. In evolutionary computation one defines some finite maximal lifespan and assigns age 0 to each new search point. In artificial immune systems static pure aging is used. There a finite maximal lifespan is defined but new search points inherit the age of their origin if they do not excel in function value. Both aging mechanisms are supposed to increase the capabilities of the respective search heuristics. A rigorous analysis for two typical difficult situations sheds light on similarities and differences. Considering the behavior on plateaus of constant function values and in local optima both methods are shown to have their strengths and weaknesses. A third aging operator is introduced that provably shares the advantages of both aging mechanisms. Experimental supplements are provided to point out practical implications of the theoretical results and discuss further issues concerning the considered aging strategies.     

Analyzing different variants of immune inspired somatic contiguous hypermutations

Artificial immune systems can be applied to a variety of very different tasks including function optimization. There are even artificial immune systems tailored specifically for this task. In spite of their successful application there is little knowledge and hardly any theoretical investigation about how and why they perform well. Here rigorous analyses for a specific class of mutation operators introduced for function optimization called somatic contiguous hypermutation is presented. Different concrete instantiations of this operator are considered and shown to behave quite differently in general. While there are serious limitations to the performance of this type of operator even for simple optimization tasks it is proven that for some types of optimization problems it performs much better than standard bit mutations most often used in evolutionary algorithms.     

Direct integration of micromachined pipettes in a flow channel forsingle DNA molecule study by optical tweezers

We have developed a micromachined flow cell consisting of a flow channel integrated with micropipettes. The flow cell is used in combination with an optical trap setup (optical tweezers) to study mechanical and structural properties of λ-DNA molecules. The flow cell was realized using silicon micromachining including the so-called buried channel technology to fabricate the micropipettes, the wet etching of glass to create the flow channel, and the powder blasting of glass to make the fluid connections. The volume of the flow cell is 2 μl. The pipettes have a length of 130 μm, a width of 5-10 μm, a round opening of 1 μm and can be processed with different shapes. Using this flow cell we stretched single molecules (λ-DNA) showing typical force-extension curves also found with conventional techniques. These pipettes can be also used for drug delivery, for injection of small gas bubbles into a liquid flow to monitor the streamlines, and for the mixing of liquids to study diffusion effects. The paper describes the design, the fabrication and testing of the flow cell     

Simulation and fabrication of piezoresistive membrane type MEMS strain sensors

Two piezoresistive (n-polysilicon) strain sensors on a thin Si₃N₄/SiO₂ membrane with improved sensitivity were successfully fabricated by using MEMS technology. The primary difference between the two designs was the number of strips of the polysilicon patterns. For each design, a doped n-polysilicon sensing element was patterned over a thin 3 μm Si₃N₄/SiO₂ membrane. A 1000×1000 μm² window in the silicon wafer was etched to free the thin membrane from the silicon wafer. The intent of this design was to fabricate a flexible MEMS strain sensor similar in function to a commercial metal foil strain gage. A finite element model of this geometry indicates that strains in the membrane will be higher than strains in the surrounding silicon. The values of nominal resistance of the single strip sensor and the multi-strip sensor were 4.6 and 8.6 kΩ, respectively. To evaluate thermal stability and sensing characteristics, the temperature coefficient of resistance [TCR=(ΔR/R₀)/ΔT] and the gage factor [GF=(ΔR/R₀)/] for each design were evaluated. The sensors were heated on a hot plate to measure the TCR. The sensors were embedded in a vinyl ester epoxy plate to determine the sensor sensitivity. The TCR was 7.5×10⁻⁴ and 9.5×10⁻⁴/°C for the single strip and the multi-strip pattern sensors. The gage factor was as high as 15 (bending) and 13 (tension) for the single strip sensor, and 4 (bending) and 21 (tension) for the multi-strip sensor. The sensitivity of these MEMS sensors is much higher than the sensitivity of commercial metal foil strain gages and strain gage alloys.     

Triggered Updates for Temporal Consistency in Real-Time Databases

A real-time database systemhas temporal consistency constraints in addition to timing constraints.The timing constraints require a transaction to be completedby a specified deadline, and the temporal consistency constraintsrequire that temporal data read by a transaction be up-to-date.If a transaction reads out-of-date data, it will become temporallyinconsistent. A real-time database system consists of differenttypes of temporal data objects, including derived objects. Thevalue of a derived object is computed from a set of other objects,known as the read-set of the derived object. The derived objectmay not always reflect the current state of its read-set; a derivedobject can become out-of-date even if its read-set is up-to-date.Any subsequent transaction reading the derived object will thenbecome temporally inconsistent. In this case, in order to readup-to-date objects, a transaction will have to wait until someother transaction updates the out-of-date object. However, indoing so, the waiting transaction may miss its deadline, particularlyif the update is not periodic but instead arrives randomly. Wepropose to update the outdated objects so that not only is thetemporal consistency improved, but also the number of misseddeadlines does not increase significantly, and as a result thereis an overall improvement in the performance of the system. Wepropose, implement and study a novel approach, to be known astriggered updates, to improve temporal consistency in firm real-timedatabase systems when updates are not periodic. We identify propertiesof triggered updates and explain how they work by giving bothan intuitive and a probabilistic analysis. We present strategiesfor generating triggered updates, discuss their suitability invarious contexts and perform a detailed simulation study to evaluatetheir performance. Results show that it is possible to improvetemporal consistency without degrading the timeliness of real-time database systems to a great deal.     

Towards understanding the mechanism of action of the multidrug resistance-linked half-ABC transporter ABCG2: a molecular modeling study

The ATP-binding cassette protein ABCG2 is a member of a broad family of ABC transporters with potential clinical importance as a mediator of multidrug resistance. We carried out a homology and knowledge-based, and mutationally improved molecular modeling study to establish a much needed structural framework for the protein, which could serve as guidance for further genetic, biochemical, and structural analyses. Based on homology with known structures of both full-length and nucleotide-binding domains (NBD) of ABC transporters and structural knowledge of integral membrane proteins, an initial model of ABCG2 was established. Subsequent refinement to conform to the lipophilic index distributions in the transmembrane domain (TMD) and to the results of site-directed mutagenesis experiments led to an improved model. The complete ABCG2 model consists of two identical subunits facing each other in a closed conformation. The dimeric interface in the nucleotide-binding domain (NBD) involves a characteristic nucleotide sandwich and the interface in the TMD consists of the TM helices 1–3 of one subunit and the helices 5 and 6 of the other. The interface between the NBD and the TMD is bridged by the conserved structural motif between TM2 and TM3, the intracellular domain 1 (ICD1), and the terminal β-strand (S6) of the central β-sheet in the NBD. The apparent flexibility of the ICD1 may play a role in transmitting conformational changes from the NBD to the TMD or from the TMD to the NBD.