On the relation between the Feynman paradox and Aharonov-Bohm effects

The magnetic Aharonov-Bohm (A-B) effect occurs when a point charge interacts with a line of magnetic flux, while its dual, the Aharonov-Casher (A-C) effect, occurs when a magnetic moment interacts with a line of charge. For the two interacting parts of these physical systems, the equations of motion are discussed in this paper. The generally accepted claim is that both parts of these systems do not accelerate, while Boyer has claimed that both parts of these systems do accelerate. Using the Euler-Lagrange equations we predict that in the case of unconstrained motion only one part of each system accelerates, while momentum remains conserved. This prediction requires a time dependent electromagnetic momentum. For our analysis of unconstrained motion the A-B effects are then examples of the Feynman paradox. In the case of constrained motion, the Euler-Lagrange equations give no forces in agreement with the generally accepted analysis. The quantum mechanical A-B and A-C phase shifts are independent of the treatment of constraint. Nevertheless, experimental testing of the above ideas and further understanding of A-B effects which is central to both quantum mechanics and electromagnetism may be possible.Comment: 21 pages, 5 figures, recently submitted to New Journal of Physic

"El nen s'ha menjat una aranya": The development of narratives in Catalan speaking children

The production of a well-constructed narrative is the culmination of several years of language acquisition and is an important milestone in children's development. There is no current description of narrative development for Catalan speaking children. This study collected elicited narratives in Catalan from 118 children aged 4;0-10;11. Narratives were scored for macrostructure and microstructure. Narrative scores improved with age with maximum performance for macrostructure by 9 years. Children's ability to use micro-structural components of Catalan is variable with some developments continuing beyond 9 years. The results are discussed in relation to theoretical arguments about universal and specific features of narrative development. We conclude by highlighting the usefulness of the new test for future language assessment of children acquiring Catalan

The Stability of Living Shorelines - An Evaluation

This project set out to strengthen arguments that living shorelines were a viable and preferred method of erosion control along much of the Chesapeake Bay shoreline. Using statistical tests and data that describe shoreline and environmental condition along tidal shoreline, the study found that indeed marshes are frequently associated with stable shoreline and therefore recommending living shoreline treatments to manage erosion problems was a reasonable strategy that warranted strong consideration. Additional tests revealed a lower occurrence of marshes when traditional erosion control structures like bulkheads and revetments were present. This confirms these structures can permanently impact the growth of tidal marshes. Consideration of alternative treatments particularly in low energy settings is recommended. Additional statistical relationships revealed that marshes were not prolific in high energy environments, suggesting the living shoreline strategy was environmentally restricted and any model would need to account for this. Under a separate task, erosion rates were computed along shoreline where living shoreline treatments were in place. While the results could not confirm that the living shoreline treatment performed better at reducing shoreline erosion rates, there was enough evidence from the 35 sites that were analyzed to confirm that erosion could be reduced using soft stabilization techniques. Based on criteria evaluated in the aforementioned analyses, a protocol was developed to model the locations where living shoreline treatments should be considered for erosion control. Using existing GIS based databases a spatially explicit model was generated. The model was tested in the county of Northumberland, Virginia located on Virginia’s Northern Neck. The model delineated areas as suitable, unsuitable, and suitable with design restrictions. The model was validated against random field inspections and permit reviews. The results indicate strong agreement (75%) between the modeled output and the field review when considering a site suitable (inclusive of design restrictions) and unsuitable. The model had less agreement (58%) between the output and the field assessment when considering explicit treatment types for suitable areas. We attribute the discrepancy largely to the limitations associated with data availability and professional bias. Despite this, the model has enormous potential as a management tool and represents the only decision making tool currently devoted to the subject of living shorelines in this region, and one of the few nationwide. The Center for Coastal Resources Management recommends the model be run throughout the Bay where data exists, and will seek avenues for funding to begin this venture. This report as well as outreach material collected as part of this project and others within the Center for Coastal Resources Management have been posted to a new Living Shoreline Website at http://ccrm.vims.edu/livingshorelines/index.htm

Hybridization and Bond-Orbital Components in Site-Specific X-Ray Photoelectron Spectra of Rutile TiO\u3csub\u3e2\u3c/sub\u3e

We have determined the Ti and O components of the rutile TiO2 valence band using the method of sitespecific x-ray photoelectron spectroscopy. Comparisons with calculations based on pseudopotentials within the local density approximation reveal the hybridization of the Ti 3d, 4s, and 4p states, and the O 2s and 2p states on each site. These chemical effects are observed due to the large differences between the angular-momentum dependent matrix elements of the photoelectron process

Acoustic Analog to Quantum Mechanical Level Splitting

A simple physical system is discussed that mirrors the quantum mechanical infinite square well with a central delta well potential. The physical realization consists of a continuous sound wave traveling in a pair of tubes separated by an adjustable diaphragm. The equivalence between the quantum system and the acoustic system is explored. The analytic solution to the quantum system exhibits level splitting as does the acoustic system

Language impairments in the development of sign: Do they reside in a specific modality or are they modality-independent deficits?

Various theories of developmental language impairments have sought to explain these impairments in modality-specific ways – for example, that the language deficits in SLI or Down syndrome arise from impairments in auditory processing. Studies of signers with language impairments, especially those who are bilingual in a spoken language as well as a sign language, provide a unique opportunity to contrast abilities across language in two modalities (cross-modal bilingualism). The aim of the article is to examine what developmental sign language impairments can tell us about the relationship between language impairments and modality. A series of individual and small group studies are presented here illustrating language impairments in sign language users and cross-modal bilinguals, comprising Landau-Kleffner syndrome, Williams syndrome, Down syndrome, Autism and SLI. We conclude by suggesting how studies of sign language impairments can assist researchers to explore how different language impairments originate from different parts of the cognitive, linguistic and perceptual systems

Seasonal changes in the biochemical fate of carbon fixed by benthic diatoms in intertidal sediments

Benthic diatoms are important primary producers in intertidal marine sediments and form the basis of the food web in these ecosystems. In order to investigate the carbon flow within diatom mats, we performed in situ 13C pulse-chase labeling experiments and followed in detail the biochemical fate of carbon fixed by the diatoms for five consecutive days. These labeling experiments were done at approximately 2-monthly intervals during 1 yr in order to cover seasonal variations. The fixed carbon was recovered in individual carbohydrates including extracellular polymeric substances (EPS), amino acids, fatty acids, and nucleic acid bases. In addition, we assessed a variety of environmental parameters and photosynthetic characteristics. The fixed carbon was initially mainly stored as carbohydrate (glucose) while nitrogen-rich compounds (e.g., amino acids and RNA/DNA) were produced more slowly. During the year, the diatoms distributed the photosynthetically fixed carbon differently among the various carbon pools that were measured. In summer, the diatoms decreased carbon fixation and accumulated relatively more lipid as a storage compound (27% 6 2% vs. 12% 6 5% in other seasons). The percentage of fixed carbon that was excreted as EPS was lower in summer compared to other seasons, amounting 9% 6 4% and 21% 6 6%, respectively. Hence, it seemed that the physiology of the microphytobenthos was different during summer and caused by higher light intensity and a shift in nitrogen source

Deficits in narrative abilities in child British Sign Language users with specific language impairment

This study details the first ever investigation of narrative skills in a group of 17 deaf signing children who have been diagnosed with disorders in their British Sign Language development compared with a control group of 17 deaf child signers matched for age, gender, education, quantity, and quality of language exposure and non-verbal intelligence. Children were asked to generate a narrative based on events in a language free video. Narratives were analysed for global structure, information content and local level grammatical devices, especially verb morphology. The language-impaired group produced shorter, less structured and grammatically simpler narratives than controls, with verb morphology particularly impaired. Despite major differences in how sign and spoken languages are articulated, narrative is shown to be a reliable marker of language impairment across the modality boundaries

Assessing the clinical utility of measuring Insulin-like Growth Factor Binding Proteins in tissues and sera of melanoma patients

<p>Abstract</p> <p>Background</p> <p>Different Insulin-like Growth Factor Binding Proteins (IGFBPs) have been investigated as potential biomarkers in several types of tumors. In this study, we examined both IGFBP-3 and -4 levels in tissues and sera of melanoma patients representing different stages of melanoma progression.</p> <p>Methods</p> <p>The study cohort consisted of 132 melanoma patients (primary, n = 72; metastatic, n = 60; 64 Male, 68 Female; Median Age = 56) prospectively enrolled in the New York University School of Medicine Interdisciplinary Melanoma Cooperative Group (NYU IMCG) between August 2002 and December 2006. We assessed tumor-expression and circulating sera levels of IGFBP-3 and -4 using immunohistochemistry and ELISA assays. Correlations with clinicopathologic parameters were examined using Wilcoxon rank-sum tests and Spearman-rank correlation coefficients.</p> <p>Results</p> <p>Median IGFBP-4 tumor expression was significantly greater in primary versus metastatic patients (70% versus 10%, p = 0.01) A trend for greater median IGFBP-3 sera concentration was observed in metastatic versus primary patients (4.9 μg/ml vs. 3.4 μg/ml, respectively, p = 0.09). However, sera levels fell within a normal range for IGFBP-3. Neither IGFBP-3 nor -4 correlated with survival in this subset of patients.</p> <p>Conclusion</p> <p>Decreased IGFBP-4 tumor expression might be a step in the progression from primary to metastatic melanoma. Our data lend support to a recently-described novel tumor suppressor role of secreting IGFBPs in melanoma. However, data do not support the clinical utility of measuring levels of IGFBP-3 and -4 in sera of melanoma patients.</p