Social Influence and the Collective Dynamics of Opinion Formation

Social influence is the process by which individuals adapt their opinion, revise their beliefs, or change their behavior as a result of social interactions with other people. In our strongly interconnected society, social influence plays a prominent role in many self-organized phenomena such as herding in cultural markets, the spread of ideas and innovations, and the amplification of fears during epidemics. Yet, the mechanisms of opinion formation remain poorly understood, and existing physics-based models lack systematic empirical validation. Here, we report two controlled experiments showing how participants answering factual questions revise their initial judgments after being exposed to the opinion and confidence level of others. Based on the observation of 59 experimental subjects exposed to peer-opinion for 15 different items, we draw an influence map that describes the strength of peer influence during interactions. A simple process model derived from our observations demonstrates how opinions in a group of interacting people can converge or split over repeated interactions. In particular, we identify two major attractors of opinion: (i) the expert effect, induced by the presence of a highly confident individual in the group, and (ii) the majority effect, caused by the presence of a critical mass of laypeople sharing similar opinions. Additional simulations reveal the existence of a tipping point at which one attractor will dominate over the other, driving collective opinion in a given direction. These findings have implications for understanding the mechanisms of public opinion formation and managing conflicting situations in which self-confident and better informed minorities challenge the views of a large uninformed majority.Comment: Published Nov 05, 2013. Open access at: http://www.plosone.org/article/info%3Adoi%2F10.1371%2Fjournal.pone.007843

Lyb-2 system of mouse B cells. Evidence for a role in the generation of antibody-forming cells

The Lyb-2 cell-surface alloantigens of the mouse are selectively and perhaps exclusively expressed in the B lymphocyte lineage, but not on antibody- forming cells. Thus if the Lyb-2 molecule is concerned in specific B cell function, it must participate in the generative phase of the antibody response. Accordingly, monoclonal Lyb-2 antibody was found to depress the plaque- forming cell (PFC) response to sheep erythrocytes in 5-d Mishell-Dutton assays when added within the first 3 d of culture, but not later. The rate of PFC generation was not affected, signifying an absolute reduction in the number of PFC generated. Because reduction of PFC counts by Lyb-2 antibody was not affected by exclusion of Lyt-2(+) T cells, it is unlikely that the reduction depends on augmented suppression by T cells. Augmented B cell- mediated suppression is also unlikely, because the PFC response of serial combinations of congenic Lyb-2.1 and Lyb-2.2 cells, in the presence of monoclonal Lyb-2.1 antibody, was reduced only in direct proportion to the number of Lyb-2.1 cells present. The PFC response of Lyb-2.1/Lyb-2.2 heterozygous cells was not reduced by Lyb-2.1 antibody, presumably because generation of PFC is impeded only if most Lyb-2 sites are blocked. Further evidence that the molecule identified by Lyb-2 plays a critical role in the generation of antibody-forming cells (AFC) in response to T-dependent antigen comes from the finding that Lyb-2 antibody does not reduce the PFC response to the T-independent antigens trinitrophenylated (TNP) Brucella abortus and TNP-FicolI, although elimination of Lyb-2(+) cells from the starting population by Lyb-2 antibody and complement reduces the PFC response to T- dependent and T-independent antigens alike

Energy Efficiency of a Chiller using R410A or R32

An advanced simulation model of a packaged air cooled water chiller was developed. The nominal cooling capacity of the chiller is about 70 kW at 35°C dry bulb outdoor air temperature, and it consists of a single refrigerating circuit with two identical scroll compressors. The compressor was characterised by its experimental performance curve according to EN 12900 for both R410A and R32. Off-the-shelf copper tubes and louvered aluminium fins were considered for the condenser and typical brazed plate configurations for the evaporator. The finned coil condenser and the brazed plate heat exchanger evaporator were modelled by an elementary finite volumes technique, previously validated in other papers; for each volume the heat transfer coefficient and the pressure drop were calculated using semi-empirical correlations chosen among the most accurate ones available in the open literature. The aim of the paper is to compare the performance of R410A with that of R32 which is considered as a possible HFC substitute with lower GWP (675 instead of 2088). The condenser was optimised for R410A and R32 independently with regard to the number of internal circuits according to the so-called Performance Evaluation Criteria [1], without changing the overall heat exchanger dimensions. An analysis of the seasonal efficiency for each finned coil circuitry configuration (both with the same compressors) was carried out in terms of European Seasonal Energy Efficiency Ratio (ESEER) calculated according to the EN 14825 specifications for water chillers. We were able to conclude from that modelling work, that R32 system efficiency performance is acceptable as alternative to R410 for water chillers and further simulation analyses will include evaluating HFO blends

Experimental investigation of the elasticity of the human diaphragm

<p>Abstract</p> <p>Background</p> <p>Traumatic diaphragmatic ruptures affect mainly the left side. In an experimental study in human corpses we examined the stretch behaviour of the left and right diaphragmatic halves.</p> <p>Methods</p> <p>In a total of 8 male and 8 female corpses each diaphragmatic half was divided into 4 different segments. Each segments stretch behaviour was investigated. In steps of 2 N the stretch was increased up to 24 N.</p> <p>Results</p> <p>In the female the left diaphragm showed a stronger elasticity compared to the right. Additionally the left diaphragm in females showed a higher elasticity in comparison to the left in males. Traumatic diaphragmatic ruptures affect mostly the central tendineous part or the junction between tendineous and muscular part of the diaphragmatic muscle. Accordingly we found a lower elasticity in these parts compared with the other diaphragmatic segments.</p> <p>Conclusion</p> <p>In summary it can be said that albeit some restrictions we were able to determine the elasticity of different diaphragmatic segments quantitatively and reproduceably with our presented method. Thereby a comparison of results of different diaphragmatic segments as well as of both diaphragmatic halves and of both genders was possible</p

New technical approach for the repair of an abdominal wall defect after a transverse rectus abdominis myocutaneous flap: a case report

<p>Abstract</p> <p>Introduction</p> <p>Breast reconstruction with autologous tissue transfer is now a standard operation, but abnormalities of the abdominal wall contour represent a complication which has led surgeons to invent techniques to minimize the morbidity of the donor site.</p> <p>Case presentation</p> <p>We report the case of a woman who had bilateral transverse rectus abdominis myocutaneous flap (TRAM-flap) breast reconstruction. The surgery led to the patient developing an enormous abdominal bulge that caused her disability in terms of abdominal wall and bowel function, pain and contour. In the absence of rectus muscle, the large defect was repaired using a combination of the abdominal wall component separation technique of Ramirez et al and additional mesh augmentation with a lightweight, large-pore polypropylene mesh (Ultrapro^®).</p> <p>Conclusion</p> <p>The procedure of Ramirez et al is helpful in achieving a tension-free closure of large defects in the anterior abdominal wall. The additional mesh augmentation allows reinforcement of the thinned lateral abdominal wall.</p

Pleiotropic effects of the vacuolar ABC transporter MLT1 of Candida albicans on cell function and virulence.

Among the several mechanisms that contribute to MDR (multidrug resistance), the overexpression of drug-efflux pumps belonging to the ABC (ATP-binding cassette) superfamily is the most frequent cause of resistance to antifungal agents. The multidrug transporter proteins Cdr1p and Cdr2p of the ABCG subfamily are major players in the development of MDR in Candida albicans Because several genes coding for ABC proteins exist in the genome of C. albicans, but only Cdr1p and Cdr2p have established roles in MDR, it is implicit that the other members of the ABC family also have alternative physiological roles. The present study focuses on an ABC transporter of C. albicans, Mlt1p, which is localized in the vacuolar membrane and specifically transports PC (phosphatidylcholine) into the vacuolar lumen. Transcriptional profiling of the mlt1∆/∆ mutant revealed a down-regulation of the genes involved in endocytosis, oxidoreductase activity, virulence and hyphal development. High-throughput MS-based lipidome analysis revealed that the Mlt1p levels affect lipid homoeostasis and thus lead to a plethora of physiological perturbations. These include a delay in endocytosis, inefficient sequestering of reactive oxygen species (ROS), defects in hyphal development and attenuated virulence. The present study is an emerging example where new and unconventional roles of an ABC transporter are being identified

Direct intra-abdominal pressure monitoring via piezoresistive pressure measurement: a technical note

<p>Abstract</p> <p>Background</p> <p>Piezoresistive pressure measurement technique (PRM) has previously been applied for direct IAP measurement in a porcine model using two different devices. Aim of this clinical study was to assess both devices regarding complications, reliability and agreement with IVP in patients undergoing elective abdominal surgery.</p> <p>Methods</p> <p>A prospective cohort study was performed in 20 patients randomly scheduled to receive PRM either by a Coach^®-probe or an Accurate++^®-probe (both MIPM, Mammendorf, Germany). Probes were placed on the greater omentum and passed through the abdominal wall paralleling routine drainages. PRM was compared with IVP measurement by t-testing and by calculating mean difference as well as limits of agreement (LA).</p> <p>Results</p> <p>There were no probe related complications. Due to technical limitations, data could be collected in 3/10 patients with Coach^®and in 7/10 patients with Accurate++^®. Analysis was carried out only for Accurate++^®. Mean values did not differ to mean IVP values. Mean difference to IVP was 0.1 ± 2.8 mmHg (LA: -5.5 to 5.6 mmHg).</p> <p>Conclusion</p> <p>Direct IAP measurement was clinically uneventful. Although results of Accurate++^®were comparable to IVP, the device might be too fragile for IAP measurements in the clinical setting. Local ethical committee trial registration: EK2024</p