Noise peaks influence communication in the operating room. An observational study

Noise peaks are powerful distractors. This study focuses on the impact of noise peaks on surgical teams’ communication during 109 long abdominal surgeries. We related measured noise peaks during 5-min intervals to the amount of observed communication during the same interval. Results show that noise peaks are associated with less case-relevant communication; this effect is moderated by the level of surgical experience; case-relevant communications decrease under high noise peak conditions among junior, but not among senior surgeons. However, case-irrelevant communication did not decrease under high noise level conditions, rather there was a trend to more case-irrelevant communication under high noise peaks. The results support the hypothesis that noise peaks impair communication because they draw on attentional resources rather than impairing understanding of communication. As case-relevant communication is important for surgical performance, exposure to high noise peaks in the OR should be minimised especially for less experienced surgeons.

Practitioner Summary: This study investigated whether noise during surgeries influenced the communication within surgical teams. During abdominal surgeries, noise levels were measured and communication was observed. Results showed that high noise peaks reduced the frequency of patient-related communication, but did not reduce patient-irrelevant communication. Noise may negatively affect team coordination in surgeries.     

A policy-based B2C e-Contract management workflow methodology using semantic web agents

Since e-Commerce has become a discipline, e-Contracts are acknowledged as the tools that will assure the safety and robustness of the transactions. A typical e-Contract is a binding agreement between parties that creates relations and obligations. It consists of clauses that address specific tasks of the overall procedure which can be represented as workflows. Similarly to e-Contracts, Intelligent Agents manage a private policy, a set of rules representing requirements, obligations and restrictions, additionally to personal data that meet their user’s interests. In this context, this study aims at proposing a policy-based e-Contract workflow management methodology that can be used by semantic web agents, since agents benefit from Semantic Web technologies for data and policy exchanges, such as RDF and RuleML that maximize interoperability among parties. Furthermore, this study presents the integration of the above methodology into a multi-agent knowledge-based framework in order to deal with issues related to rules exchange where no common syntax is used, since this framework provides reasoning services that assist agents in interpreting the exchanged policies. Finally, a B2C e-Commerce scenario is presented that demonstrates the added value of the approach.     

Solid state reaction in sandwich-type Al/Cu thin films

Al/Cu/Al and Cu/Al/Cu triple layers with approximately 10 nm single layer thickness deposited on tungsten substrates were analyzed in the early stages of reactive interdiffusion by means of atom probe tomography. The first reaction product is found after 5 min thermal treatment at 110 degrees C and identified by direct chemical analysis to be Al2Cu. Surprisingly, we found a significant asymmetry in the reaction rate of the new phase with the stacking sequence: the thickness of the product grown at the interfaces, at which Cu is deposited on top of the Al layer, is approximately 1.5-2 times thicker than the other one at the interfaces at which Al is deposited onto a Cu layer. On the other hand, at both interfaces the thickness of the product layer depends parabolically on time. No precursory interdiffusion and no distinct nucleation process of the product are observed.     

Computational models of myocardial endomysial collagen arrangement

Collagen extracellular matrix is one of the factors related to high passive stiffness of cardiac muscle. However, the architecture and the mechanical aspects of the cardiac collagen matrix are not completely known. In particular, endomysial collagen contribution to the passive mechanics of cardiac muscle as well as its micro anatomical arrangement is still a matter of debate. In order to investigate mechanical and structural properties of endomysial collagen, we consider two alternative computational models of some specific aspects of the cardiac muscle. These two models represent two different views of endomysial collagen distribution: (1) the traditional view and (2) a new view suggested by the data obtained from scanning electron microscopy (SEM) in NaOH macerated samples (a method for isolating collagen from the other tissue). We model the myocardial tissue as a net of spring elements representing the cardiomyocytes together with the endomysial collagen distribution. Each element is a viscous elastic spring, characterized by an elastic and a viscous constant. We connect these springs to imitate the interconnections between collagen fibers. Then we apply to the net of springs some external forces of suitable magnitude and direction, obtaining an extension of the net itself. In our setting, the ratio forces magnitude /net extension is intended to model the stress /strain ratio of a microscopical portion of the myocardial tissue. To solve the problem of the correct identification of the values of the different parameters involved, we use an artificial neural network approach. In particular, we use this technique to learn, given a distribution of external forces, the elastic constants of the springs needed to obtain a desired extension as an equilibrium position. Our experimental findings show that, in the model of collagen distribution structured according to the new view, a given stress /strain ratio (of the net of springs, in the sense specified above) is obtained with much smaller (w.r.t. the other model, corresponding to the traditional view) elasticity constants of the springs. This seems to indicate that by an appropriate structure, a given stiffness of the myocardial tissue can be obtained with endomysial collagen fibers of much smaller size.     

Human eye-head co-ordination in natural exploration

During natural behavior humans continuously adjust their gaze by moving head and eyes, yielding rich dynamics of the retinal input. Sensory coding models, however, typically assume visual input as smooth or a sequence of static images interleaved by volitional gaze shifts. Are these assumptions valid during free exploration behavior in natural environments? We used an innovative technique to simultaneously record gaze and head movements in humans, who freely explored various environments (forest, train station, apartment). Most movements occur along the cardinal axes, and the predominance of vertical or horizontal movements depends on the environment. Eye and head movements co-occur more frequently than their individual statistics predicts under an independence assumption. The majority of co-occurring movements point in opposite directions, consistent with a gaze-stabilizing role of eye movements. Nevertheless, a substantial fraction of eye movements point in the same direction as co-occurring head movements. Even under the very most conservative assumptions, saccadic eye movements alone cannot account for these synergistic movements. Hence nonsaccadic eye movements that interact synergistically with head movements to adjust gaze cannot be neglected in natural visual input. Natural retinal input is continuously dynamic, and cannot be faithfully modeled as a mere sequence of static frames with interleaved large saccades.     

Morphological patterns of angiogenesis in ovarian follicle capillary networks. A scanning electron microscopy study of corrosion cast

To describe the morphological characteristics of the ovarian follicle (F) capillary neoformation and regression, the angiogenic figures were studied by means of scanning electron microscopy of corrosion casts in developing and mature F of rabbit, pig, and cow. Developing F showed gradual neoformation of thecal capillaries characterized by budding and then sprouting, likely from preexisting interstitial vessels. Postcapillary venules frequently showed vasoconstriction rings (sphincters). Vasodilation followed capillary elongation. Mature F, in addition to vessel elongation and dilation, also presented infolding of dilated capillary walls, followed by capillary duplication and sinusoidalization. Periovulatory F mainly showed functional changes, such as capillary dilation, signs of iperpermeabilization, and ischemia, the latter being limited to the apical follicular area. Vessel regression was characterized by thinning of capillaries and presence of avascular areas within the atretic F wall at any stage. This study showed two main types of angiogenic patterns. (a) longitudinal elongation (in series, sprouting angiogenesis) characterizing the initial phase of F development and (b) parallel duplication (in parallel, infolding or intussusceptive angiogenesis), ending in capillary lateral replication or splitting, secondary to functional microvascular changes. Indirect evidence of the establishment of postcapillary resistances contributing to capillary remodeling, was also shown. It is concluded that the sequence of capillary neoformation in mammalian ovarian F occurs in six steps: (1) budding, (2) sprouting (and elongation), (3) dilation, (4) infolding (intussusception), (5) duplication (splitting and elongation), and (6) sinusoidalization. Capillary regression hits F at any stage and characterizes F atresia.     

Estimating the Impact of Water Pricing on Water Use Efficiency in Semi-arid Cropping System: An Application of Probabilistically Constrained Nonparametric Efficiency Analysis

By introducing proper pricing instruments, farm level water can be used more efficient. But it demands a proper estimation strategy to analyse the efficiency and the input use behavior of farms under the new pricing system. As most production relationships are stochastic in nature, excluding random errors and noise from model specifications often leads to criticism. By using a probabilistically constrained programming formulation, an empirical estimation of stochastic data envelopment analysis (DEA) is done to analyze the efficiency of irrigation water use in the agricultural production system in the Krishna river basin, India. The results illustrate that water demand is higher for farms at, or close to the frontier and lower for those with low efficiency levels. In a second step, a simulation model is developed by using the frontier and economic efficiency derived from stochastic DEA to analyse the impact of water pricing on water use efficiency and water use behaviour. It is shown that an increase in the water price would not cause sizeable profit loss, if the pricing system is administered on a volumetric basis, but water demand would decrease substantially.     

Geometry and Stacking Sequence Effect on Composite Spinnaker Pole's Stiffness: Experimental and Numerical Analysis

Composite materials are widely employed in sailing sports, a possible application is for the mast pole or other sail poles. In the paper the attention is focused on the spinnaker poles mechanical performances; in particular the focus is on axial and ring compressive properties of three different carbon fibre/epoxy resin spinnaker poles, to investigate both the diameter and stacking sequence effect on the mechanical performance of the structure. Starting from the stacking sequence used in the production of a particular spinnaker pole, the effect of a lamina at 0° in the middle of wall thickness is investigated with the purpose to obtain a more stiff structure. Moreover to test the proposed stacking sequence on different size products, a prototype with lower diameter is realized. To properly evaluate axial and ring stiffness, axial compression test and ring stiffness one are performed. Then a numerical model is developed to support the design of the finished product: A simple and versatile numerical analysis (FEA with software ANSYS), by simulating ring stiffness and pull-direction compression tests, is carried out in elastic regime. Such model should be suitable for designing and/or verifying the mechanical performance of pole structures, even though differing from those above described, for materials, geometry and stacking sequence.     

Electrochemical corrosion behavior of carbon-based thin films in chloride ions containing electrolytes

Commercially available carbon-based thin films consisting of single layers of amorphous diamond-like carbon or multilayers of crystalline TiAlN or CrN with diamond-like carbon top coatings were evaluated in relation to their electrochemical corrosion behavior in chloride ions containing electrolytes. The hardened working steel (an alloy of 0.9% C, 4.1% Cr, 4.9% Mo, 1.8% V, 6.4% W) was used as a substrate material.The potentiodynamic corrosion behavior of coated samples was tested in 3.5 wt.% NaCl solution and Hank's balanced body solution, HBBS (0.89 wt.% NaCl, further chlorides, sulfates, carbonates and phosphates). The multi-layers TiAlN + a-C:H:W and CrN + a-C:H:W exhibited only a minor improvement in corrosion resistance. Single layers of amorphous diamond-like carbon coating without hydrogen (a-C) spall off during the corrosion tests in chloride containing media. A minor improvement of the corrosion resistance is possible. The a-C:H and the a-C:H:Si, which contain hydrogen, showed the best corrosion resistance with a 100 times lower corrosion current density.     

The beat goes on: Rhythmic modulation of cortical potentials by imagined tapping.

A frequency analysis was used to tag cortical activity from imagined rhythmic movements. Participants synchronized overt and imagined taps with brief visual stimuli presented at a constant rate, alternating between left and right index fingers. Brain potentials were recorded from across the scalp and topographic maps made of their power at the alternation frequency between left and right taps. Two prominent power foci occurred in each hemisphere for both overt and imagined taps, one over sensorimotor cortex and the other over posterior parietal cortex, with homologous foci in opposite hemispheres arising from oscillations 180° out of phase. These findings demonstrate temporal isomorphism at a neural level between overt and imagined movements and illustrate a new approach to studying covert actions. (PsycINFO Database Record (c) 2011 APA, all rights reserved)