Enhanced nonlinear optical effects with a tapered plasmonic waveguide

Infrared surface plasmon polaritons (SPPs) are concentrated in a laterally tapered planar Ag waveguide. The near field of SPPs excited with 1490 nm light at a Ag-sapphire interface is probed using the photoluminescence of upconverted Er ions at 550 and 660 nm. SPP interference patterns are observed that exhibit clear evidence of SPP concentration toward the taper end. The concentration leads to an enhancement of the upconversion luminescence intensity from Er energy levels that are populated by multiphoton processes.     

Rearrangement status of the malignant cell determines type of secondary IgH rearrangement (V-replacement or V to DJ joining) in childhood B precursor acute lymphoblastic leukemia

Immunoglobulin heavy chain (IgH) oligoclonality in childhood B precursor acute lymphoblastic leukemia (ALL) as determined by Southern analysis is found in 30-50% of patients and has been shown to be the result of ongoing IgH rearrangement (mostly V(H)-replacement and V(H) to D-J(H) joining) after malignant transformation. It is unknown however, what determines the type of secondary rearrangement. Also the biological basis of the variable degree of oligoclonality observed in childhood ALL is poorly understood. We analyzed in detail the IgH rearrangement status of the leukemic cells for a random panel of 18 childhood B precursor ALL patients by polymerase chain reaction (PCR)/sequencing analysis and by Southern analysis. By Southern analysis 10/18 (55.6%) patients were considered oligoclonal and 8/18 (44.4%) monoclonal. In contrast, by PCR minor clonal rearrangements were detected in 14/18 (77.8%) patients. V(H)-replacement was found in 7/14 patients, V(H) to D-J(H) joining in 6/14 patients and an unusual type of secondary rearrangement, V(H)-D to J(H) joining, in one patient. Only a single type of secondary rearrangement was detected in each patient. The type of secondary rearrangement (V(H)-replacement or V(H) to D-J(H) joining) depended on the rearrangement status (VDJ/VDJ or VDJ/DJ, respectively) of the dominant leukemic clone as determined by Southern analysis. We found that in addition to a more 'advanced' IgH rearrangement status patients with V(H)-replacements also have a more 'advanced' TCRdelta rearrangement status, which possibly reflects exposure of both the IgH locus and the TCRdelta locus to recombinase activity in a preleukemic clone. Finally, we investigated a putative relationship between oligoclonality by Southern analysis and S-phase fraction of the leukemic cell population. We found a significantly lower percentage cells in S-phase for oligoclonal patients as compared to monoclonal patients. Our data add to the understanding of ongoing rearrangement of antigen receptor loci in childhood ALL and have implications for the monitoring of minimal residual disease by PCR.     

Are there species-universal categories in bird song phonology and syntax? A comparative study of chaffinches (Fringilla coelebs), zebra finches (Taenopygia guttata), and swamp sparrows (Melospiza georgiana).

Previous studies of learned bird song have suggested the existence of species-universal patterns in song organization: clear clusters in produced songs that do not vary within a species. Here the authors combine a computational method of comparing songs with statistical methods of assessing cluster structure to investigate this issue in a more quantitative manner. The authors first analyze song phonology and then examine song syntax at a population level in 3 species with very different song structure: chaffinches (Fringilla coelebs), zebra finches (Taenopygia guttata), and swamp sparrows (Melospiza georgiana). The authors used a dynamic time-warping algorithm to compare song elements, which closely matched the judgments of human observers. Clustering tendency and validation statistics showed that broad phonological categories existed in all 3 species, but these categories explained no more than half of the overall phonological variation. The authors developed a novel statistic to assess syntactical structure, which indicated that element transitions were not randomly distributed. In the clearest case, in chaffinches, this could be explained by syllables being linked to certain positions within the song. These results demonstrate measures of song organization that can be applied across species, enhancing the potential of comparative studies. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Multi-Omics Profiling in Marfan Syndrome: Further Insights into the Molecular Mechanisms Involved in Aortic Disease

Thoracic aortic aneurysm is a potentially life-threatening disease with a strong genetic contribution. Despite identification of multiple genes involved in aneurysm formation, little is known about the specific underlying mechanisms that drive the pathological changes in the aortic wall. The aim of our study was to unravel the molecular mechanisms underlying aneurysm formation in Marfan syndrome (MFS). We collected aortic wall samples from FBN1 variant-positive MFS patients (n = 6) and healthy donor hearts (n = 5). Messenger RNA (mRNA) expression levels were measured by RNA sequencing and compared between MFS patients and controls, and between haploinsufficient (HI) and dominant negative (DN) FBN1 variants. Immunohistochemical staining, proteomics and cellular respiration experiments were used to confirm our findings. FBN1 mRNA expression levels were highly variable in MFS patients and did not significantly differ from controls. Moreover, we did not identify a distinctive TGF-β gene expression signature in MFS patients. On the contrary, differential gene and protein expression analysis, as well as vascular smooth muscle cell respiration measurements, pointed toward inflammation and mitochondrial dysfunction. Our findings confirm that inflammatory and mitochondrial pathways play important roles in the pathophysiological processes underlying MFS-related aortic disease, providing new therapeutic options.     

The influence of online store beliefs on consumer online impulse buying: A model and empirical application

Our study provides insight into the relationships between online store beliefs and consumer online impulse buying behavior. Drawing upon cognitive emotion theory, we developed a model and showed how beliefs about functional convenience (online store merchandise attractiveness and ease of use) and about representational delight (enjoyment and website communication style) related to online impulse buying. The model was tested using survey data from 532 customers of a Dutch online store. Our results showed significant effects of merchandise attractiveness, enjoyment, and online store communication style, mediated by consumers’ emotions. The study should enhance our understanding of online impulse buying and, by assessing the impact of the online store, of beliefs in non-rational decision-making settings.     

A critical review of Knowledge-Based Engineering: An identification of research challenges

Knowledge-Based Engineering (KBE) is a research field that studies methodologies and technologies for capture and re-use of product and process engineering knowledge. The objective of KBE is to reduce time and cost of product development, which is primarily achieved through automation of repetitive design tasks while capturing, retaining and re-using design knowledge. Published research on KBE is not very extensive and also quite dispersed; this paper is an effort to collect and review existing literature on KBE. A total of 50 research contributions have been analysed. The main objectives of this analysis are to identify the theoretical foundations of KBE and to identify research issues within KBE, pointing out the challenges and pitfalls that currently prohibit a wider adoption of KBE while suggesting avenues for further research. Key findings include (a) the necessity for improved methodological support and adherence, (b) better transparency and traceability of knowledge, (c) the necessity for a quantitative framework to assess the viability and success of KBE development and implementation projects, and (d) the opportunity to move towards mass customization approaches through distributed deployment of KBE in the extended enterprise.     

Virtual Customer Service Agents: Using Social Presence and Personalization to Shape Online Service Encounters

By performing tasks traditionally fulfilled by service personnel and having a humanlike appearance, virtual customer service agents bring classical service elements to the web, which may positively influence customer satisfaction through eliciting social responses and feelings of personalization. This paper sheds light on these dynamics by proposing and testing a model drawing upon the theories of implicit personality, social response, emotional contagion, and social interaction. The model proposes friendliness, expertise, and smile as determinants of social presence, personalization, and online service encounter satisfaction. An empirical study confirms the cross‐channel applicability of friendliness and expertise as determinants of social presence and personalization. Overall, the study underlines that integration between technology and personal aspects may lead to more social online service encounters.     

Online purchase intentions: A multi-channel store image perspective

The advantages of the bricks-and-clicks retail format in the battle for the online customer has been widely discussed but empirical research on it has been limited. We applied a multi-channel store image perspective to assess its influence on online purchase intentions. Drawing on a sample of 630 customers of a large music retail store in the Netherlands, the results demonstrated that offline and online store perceptions directly influenced online purchase intention. In addition, our findings confirmed that offline store impressions were used as references for their online store counterparts. Synergy and reference effects are discussed.     

Understanding users’ motivations to engage in virtual worlds: A multipurpose model and empirical testing

Despite the growth and commercial potential of virtual worlds, relatively little is known about what drives users’ motivations to engage in virtual worlds. This paper proposes and empirically tests a conceptual model aimed at filling this research gap. Given the multipurpose nature of virtual words the model integrates extrinsic and intrinsic motivation as behavioral determinants. By making use of the literature on information system value and motivation theory four important system-specific virtual world characteristics (economic value, ease of use, escapism, visual attractiveness) are added as motivational drivers. Using structural equation modeling on a sample of 846 users of the virtual world Second Life the hypotheses were tested. The results support the model; they confirm the role of extrinsic and intrinsic motivation as behavioral determinants and show how and to what extent the four system-specific elements function as motivational basis. Implications for research and practice are discussed.     

Ten years of personal neutron dosimetry with albedo dosemeters in The Netherlands

Since 1987, the dosimetry service of the Netherlands Energy Research Foundation (ECN) has been certified by the Dutch government to perform personal dosimetry, using thermoluminescence dosemeters (TLDs). Performing neutron personal dosimetry requires a rather large investment in readers, TLDs and personnel to operate the service. About 800 persons are subjected to routine neutron monitoring in The Netherlands and their annual neutron doses are a relatively small fraction (less than 10%) of the annual Hp(10). In general, the measured neutron dose values are low (on average 93% of the users receive an annual neutron dose <0.2 mSv). The collective annual (neutron) dose has tended to decrease since 1992, but incidentally high doses have been observed. Leaving these incidents out, the average collective annual neutron doses for the different users of neutron sources are about the same.