253 research outputs found
Recommended from our members
Consumer inattention and firm behavior
Lack of information distorts markets, and communicating product value to potential consumers is a crucial ingredient of marketing strategy. However, a large body of behavioral research has suggested that even when information is easily accessible, consumers often fail to attend to it. Evidence of consumer inattention has been studied in various settings, both inside and outside the laboratory. How an intermediary should react when communication fails as a result of consumers’ failure to use the provided information is unclear. Can or should firms profit from asymmetric information caused by consumer inattention? If so, by how much? Does competition alleviate the effect? We consider these questions in the context of resale markets, both theoretically and empirically. The theoretical model demonstrates that a centralized intermediary can extract surplus from serving consumers who are less attentive and, as a result, overestimate the product value. We test the theory using a detailed dataset of millions of automobile transactions from a seven-year period. First, we find clear evidence of a specific type of inattention: Buyers exhibit left-digit bias and systematically underestimate the depreciation of vehicles that have odometer readings immediately below round cutoffs. Second, the estimated level of inattention is twice as high in dealership transactions than in consumer transactions, so that dealers make a significantly higher margin on such vehicles. Third, we estimate the supply-side response to consumer inattention and find 2.53% additional transactions, compared to the no-inattention counterfactual. As a result, the average margin is 1.8% higher, leading to an aggregate increase in operating profits of 4.37%, or about 700 million.Marketin
Highly versatile atomic micro traps generated by multifrequency magnetic field modulation
We propose the realization of custom-designed adiabatic potentials for cold
atoms based on multimode radio frequency radiation in combination with static
inhomogeneous magnetic fields. For example, the use of radio frequency combs
gives rise to periodic potentials acting as gratings for cold atoms. In strong
magnetic field gradients the lattice constant can be well below 1 micrometer.
By changing the frequencies of the comb in time the gratings can easily be
propagated in space, which may prove useful for Bragg scattering atomic matter
waves. Furthermore, almost arbitrarily shaped potential are possible such as
disordered potentials on a scale of several 100 nm or lattices with a spatially
varying lattice constant. The potentials can be made state selective and, in
the case of atomic mixtures, also species selective. This opens new
perspectives for generating tailored quantum systems based on ultra cold single
atoms or degenerate atomic and molecular quantum gases.Comment: 12 pages, 6 figure
Self-assembly of Microcapsules via Colloidal Bond Hybridization and Anisotropy
Particles with directional interactions are promising building blocks for new
functional materials and may serve as models for biological structures.
Mutually attractive nanoparticles that are deformable due to flexible surface
groups, for example, may spontaneously order themselves into strings, sheets
and large vesicles. Furthermore, anisotropic colloids with attractive patches
can self-assemble into open lattices and colloidal equivalents of molecules and
micelles. However, model systems that combine mutual attraction, anisotropy,
and deformability have---to the best of our knowledge---not been realized.
Here, we synthesize colloidal particles that combine these three
characteristics and obtain self-assembled microcapsules. We propose that mutual
attraction and deformability induce directional interactions via colloidal bond
hybridization. Our particles contain both mutually attractive and repulsive
surface groups that are flexible. Analogous to the simplest chemical bond,
where two isotropic orbitals hybridize into the molecular orbital of H2, these
flexible groups redistribute upon binding. Via colloidal bond hybridization,
isotropic spheres self-assemble into planar monolayers, while anisotropic
snowman-like particles self-assemble into hollow monolayer microcapsules. A
modest change of the building blocks thus results in a significant leap in the
complexity of the self-assembled structures. In other words, these relatively
simple building blocks self-assemble into dramatically more complex structures
than similar particles that are isotropic or non-deformable
Disorder-induced trapping versus Anderson localization in Bose-Einstein condensates expanding in disordered potentials
We theoretically investigate the localization of an expanding Bose-Einstein
condensate with repulsive atom-atom interactions in a disordered potential. We
focus on the regime where the initial inter-atomic interactions dominate over
the kinetic energy and the disorder. At equilibrium in a trapping potential and
for small disorder, the condensate shows a Thomas-Fermi shape modified by the
disorder. When the condensate is released from the trap, a strong suppression
of the expansion is obtained in contrast to the situation in a periodic
potential with similar characteristics. This effect crucially depends on both
the momentum distribution of the expanding BEC and the strength of the
disorder. For strong disorder, the suppression of the expansion results from
the fragmentation of the core of the condensate and from classical reflections
from large modulations of the disordered potential in the tails of the
condensate. We identify the corresponding disorder-induced trapping scenario
for which large atom-atom interactions and strong reflections from single
modulations of the disordered potential play central roles. For weak disorder,
the suppression of the expansion signals the onset of Anderson localization,
which is due to multiple scattering from the modulations of the disordered
potential. We compute analytically the localized density profile of the
condensate and show that the localization crucially depends on the correlation
function of the disorder. In particular, for speckle potentials the long-range
correlations induce an effective mobility edge in 1D finite systems. Numerical
calculations performed in the mean-field approximation support our analysis for
both strong and weak disorder.Comment: New Journal of Physics; focus issue "Quantum Correlations in Tailored
Matter - Common perspectives of mesoscopic systems and quantum gases"; 30
pages, 10 figure
Severe airway stenosis associated with Crohn's disease: Case report
BACKGROUND: Symptomatic respiratory tract involvement is not common in Crohn's disease. Upper-airway obstruction has been reported before in Crohn's disease and usually responds well to steroid treatment. CASE PRESENTATION: We report a case of a 32-year old patient with Crohn's disease who presented with progressively worsening dyspnea on exertion. Magnetic Resonance Imaging of the chest and bronchoscopy revealed severe tracheal stenosis and marked inflammation of tracheal mucosa. Histopathology of the lesion showed acute and chronic inflammation and extended ulceration of bronchial mucosa, without granulomas. Tracheal stenosis was attributed to Crohn's disease after exclusion of other possible causes and oral and inhaled steroids were administered. Despite steroid treatment, tracheal stenosis persisted and only mild symptomatic improvement was noted after 8 months of therapy. The patient subsequently underwent rigid bronchoscopy with successful dilatation and ablation of the stenosed areas and remission of her symptoms. CONCLUSION: Respiratory involvement in Crohn's disease might be more common than appreciated. Interventional pulmonology techniques should be considered in cases of tracheal stenosis due to Crohn's disease refractory to steroid treatment
Ecological implications of a flower size/number trade-off in tropical forest trees
Peer reviewedPublisher PD
Physics with Coherent Matter Waves
This review discusses progress in the new field of coherent matter waves, in
particular with respect to Bose-Einstein condensates. We give a short
introduction to Bose-Einstein condensation and the theoretical description of
the condensate wavefunction. We concentrate on the coherence properties of this
new type of matter wave as a basis for fundamental physics and applications.
The main part of this review treats various measurements and concepts in the
physics with coherent matter waves. In particular we present phase manipulation
methods, atom lasers, nonlinear atom optics, optical elements, interferometry
and physics in optical lattices. We give an overview of the state of the art in
the respective fields and discuss achievements and challenges for the future
Genetic risk variants associated with in situ breast cancer
INTRODUCTION:
Breast cancer in situ (BCIS) diagnoses, a precursor lesion for invasive breast cancer, comprise about 20 % of all breast cancers (BC) in countries with screening programs. Family history of BC is considered one of the strongest risk factors for BCIS.
METHODS:
To evaluate the association of BC susceptibility loci with BCIS risk, we genotyped 39 single nucleotide polymorphisms (SNPs), associated with risk of invasive BC, in 1317 BCIS cases, 10,645 invasive BC cases, and 14,006 healthy controls in the National Cancer Institute's Breast and Prostate Cancer Cohort Consortium (BPC3). Using unconditional logistic regression models adjusted for age and study, we estimated the association of SNPs with BCIS using two different comparison groups: healthy controls and invasive BC subjects to investigate whether BCIS and BC share a common genetic profile.
RESULTS:
We found that five SNPs (CDKN2BAS-rs1011970, FGFR2-rs3750817, FGFR2-rs2981582, TNRC9-rs3803662, 5p12-rs10941679) were significantly associated with BCIS risk (P value adjusted for multiple comparisons <0.0016). Comparing invasive BC and BCIS, the largest difference was for CDKN2BAS-rs1011970, which showed a positive association with BCIS (OR = 1.24, 95 % CI: 1.11-1.38, P = 1.27 x 10(-4)) and no association with invasive BC (OR = 1.03, 95 % CI: 0.99-1.07, P = 0.06), with a P value for case-case comparison of 0.006. Subgroup analyses investigating associations with ductal carcinoma in situ (DCIS) found similar associations, albeit less significant (OR = 1.25, 95 % CI: 1.09-1.42, P = 1.07 x 10(-3)). Additional risk analyses showed significant associations with invasive disease at the 0.05 level for 28 of the alleles and the OR estimates were consistent with those reported by other studies.
CONCLUSIONS:
Our study adds to the knowledge that several of the known BC susceptibility loci are risk factors for both BCIS and invasive BC, with the possible exception of rs1011970, a putatively functional SNP situated in the CDKN2BAS gene that may be a specific BCIS susceptibility locus
The effect of mechanical loading on osteogenesis of human dental pulp stromal cells in a novel in vitro model
Tooth loss often results in alveolar bone resorption because of lack of mechanical stimulation. Thus, the mechanism of mechanical loading on stem cell osteogenesis is crucial for alveolar bone regeneration. We have investigated the effect of mechanical loading on osteogenesis in human dental pulp stromal cells (hDPSCs) in a novel in vitro model. Briefly, 1 × 107 hDPSCs were seeded into 1 ml 3 % agarose gel in a 48-well-plate. A loading tube was then placed in the middle of the gel to mimic tooth-chewing movement (1 Hz, 3 × 30 min per day, n = 3). A non-loading group was used as a control. At various time points, the distribution of live/dead cells within the gel was confirmed by fluorescence markers and confocal microscopy. The correlation and interaction between the factors (e.g. force, time, depth and distance) were statistically analysed. The samples were processed for histology and immunohistochemistry. After 1-3 weeks of culture in the in-house-designed in vitro bioreactor, fluorescence imaging confirmed that additional mechanical loading increased the viable cell numbers over time as compared with the control. Cells of various phenotypes formed different patterns away from the reaction tube. The cells in the middle part of the gel showed enhanced alkaline phosphatase staining at week 1 but reduced staining at weeks 2 and 3. Additional loading enhanced Sirius Red and type I collagen staining compared with the control. We have thus successfully developed a novel in-house-designed in vitro bioreactor mimicking the biting force to enhance hDPSC osteogenesis in an agarose scaffold and to promote bone formation and/or prevent bone resorption
KoVariome: Korean National Standard Reference Variome database of whole genomes with comprehensive SNV, indel, CNV, and SV analyses
High-coverage whole-genome sequencing data of a single ethnicity can provide a useful catalogue of population-specific genetic variations, and provides a critical resource that can be used to more accurately identify pathogenic genetic variants. We report a comprehensive analysis of the Korean population, and present the Korean National Standard Reference Variome (KoVariome). As a part of the Korean Personal Genome Project (KPGP), we constructed the KoVariome database using 5.5 terabases of whole genome sequence data from 50 healthy Korean individuals in order to characterize the benign ethnicity-relevant genetic variation present in the Korean population. In total, KoVariome includes 12.7M single-nucleotide variants (SNVs), 1.7M short insertions and deletions (indels), 4K structural variations (SVs), and 3.6K copy number variations (CNVs). Among them, 2.4M (19%) SNVs and 0.4M (24%) indels were identified as novel. We also discovered selective enrichment of 3.8M SNVs and 0.5M indels in Korean individuals, which were used to filter out 1,271 coding-SNVs not originally removed from the 1,000 Genomes Project when prioritizing disease-causing variants. KoVariome health records were used to identify novel disease-causing variants in the Korean population, demonstrating the value of high-quality ethnic variation databases for the accurate interpretation of individual genomes and the precise characterization of genetic variation
- …