3,348 research outputs found
Altered functional and structural brain network organization in autism.
Structural and functional underconnectivity have been reported for multiple brain regions, functional systems, and white matter tracts in individuals with autism spectrum disorders (ASD). Although recent developments in complex network analysis have established that the brain is a modular network exhibiting small-world properties, network level organization has not been carefully examined in ASD. Here we used resting-state functional MRI (n = 42 ASD, n = 37 typically developing; TD) to show that children and adolescents with ASD display reduced short and long-range connectivity within functional systems (i.e., reduced functional integration) and stronger connectivity between functional systems (i.e., reduced functional segregation), particularly in default and higher-order visual regions. Using graph theoretical methods, we show that pairwise group differences in functional connectivity are reflected in network level reductions in modularity and clustering (local efficiency), but shorter characteristic path lengths (higher global efficiency). Structural networks, generated from diffusion tensor MRI derived fiber tracts (n = 51 ASD, n = 43 TD), displayed lower levels of white matter integrity yet higher numbers of fibers. TD and ASD individuals exhibited similar levels of correlation between raw measures of structural and functional connectivity (n = 35 ASD, n = 35 TD). However, a principal component analysis combining structural and functional network properties revealed that the balance of local and global efficiency between structural and functional networks was reduced in ASD, positively correlated with age, and inversely correlated with ASD symptom severity. Overall, our findings suggest that modeling the brain as a complex network will be highly informative in unraveling the biological basis of ASD and other neuropsychiatric disorders
Lack of correlation of stem cell markers in breast cancer stem cells
BACKGROUND: Various markers are used to identify the unique sub-population of breast cancer cells with stem cell properties. Whether these markers are expressed in all breast cancers, identify the same population of cells, or equate to therapeutic response is controversial. METHODS: We investigated the expression of multiple cancer stem cell markers in human breast cancer samples and cell lines in vitro and in vivo, comparing across and within samples and relating expression with growth and therapeutic response to doxorubicin, docetaxol and radiotherapy. RESULTS: CD24, CD44, ALDH and SOX2 expression, the ability to form mammospheres and side-population cells are variably present in human cancers and cell lines. Each marker identifies a unique rather than common population of cancer cells. In vivo, cells expressing these markers are not specifically localized to the presumptive stem cell niche at the tumour/stroma interface. Repeated therapy does not consistently enrich cells expressing these markers, although ER-negative cells accumulate. CONCLUSIONS: Commonly employed methods identify different cancer cell sub-populations with no consistent therapeutic implications, rather than a single population of cells. The relationships of breast cancer stem cells to clinical parameters will require identification of specific markers or panels for the individual cancer
Rheumatoid leptomeningitis presenting with an acute neuropsychiatric disorder
Leptomeningitis is a rare central nervous system manifestation of rheumatoid arthritis, generally in patients with established chronic rheumatoid disease. We report a 41-year-old man without previous rheumatoid arthritis or psychiatric disorder who presented with an acute neuropsychiatric disturbance and polyarthralgia. His MR scan of brain showed asymmetric bifrontal leptomeningitis, confirmed on (18F)-fluoro-D-glucose-positron emission tomography. Other investigations showed highly positive serum and cerebrospinal fluid anti-cyclic citrullinated peptide. A leptomeningeal biopsy showed necrotising leptomeningeal inflammation with ill-defined granulomas and lymphoplasmacytic infiltrate without organisms. Prolonged high-dose corticosteroids and then rituximab resulted in recovery. Chronic leptomeningitis can present with an acute neuropsychiatric disorder. We highlight that early rheumatoid disease can, rarely, cause a chronic leptomeningitis, reversible with immunotherapy
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State of the California current 2012-13: No such thing as an “average” year
This report reviews the state of the California Current System (CCS) between winter 2012 and spring 2013, and includes observations from Washington State to Baja California. During 2012, large-scale climate modes indicated the CCS remained in a cool, productive phase present since 2007. The upwelling season was delayed north of 42°N, but regions to the south, especially 33° to 36°N, experienced average to above average upwelling that persisted throughout the summer. Contrary to the indication of high production suggested by the climate indices, chlorophyll observed from surveys and remote sensing was below average along much of the coast. As well, some members of the forage assemblages along the coast experienced low abundances in 2012 surveys. Specifically, the concentrations of all lifestages observed directly or from egg densities of Pacific sardine, Sardinops sagax, and northern anchovy, Engraulis mordax, were less than previous years’ survey estimates. However, 2013 surveys and observations indicate an increase in abundance of northern anchovy. During winter 2011/2012, the increased presence of northern copepod species off northern California was consistent with stronger southward transport. Krill and small-fraction zooplankton abundances, where examined, were generally above average. North of 42°N, salps returned to typical abundances in 2012 after greater observed concentrations in 2010 and 2011. In contrast, salp abundance off central and southern California increased after a period of southward transport during winter 2011/2012. Reproductive success of piscivorous Brandt’s cormorant, Phalacrocorax penicillatus, was reduced while planktivorous Cassin’s auklet, Ptychoramphus aleuticus was elevated. Differences between the productivity of these two seabirds may be related to the available forage assemblage observed in the surveys. California sea lion pups from San Miguel Island were undernourished resulting in a pup mortality event perhaps in response to changes in forage availability. Limited biological data were available for spring 2013, but strong winter upwelling coastwide indicated an early spring transition, with the strong upwelling persisting into early summer
A crack in the facade? Situating Singapore in global flows of electronic waste
Singapore is alleged to be a key node in global flows of e‐waste prohibited under the Basel Convention. We combine a close reading of the Convention and related documents with findings from nonparticipant observation of and interviews with Singapore‐based traders of discarded electronics. The case offers both important conceptual and empirical findings for future studies of territory in market‐making activity. Conceptually, our research suggests that it may be analytically useful in such studies to conceptualize territory without presupposing that it is generated as a result of separate domains or logics such as ‘the political’ or ‘the economic’. Empirically, we find that the regulatory framework of the Convention, combined with the action of traders based in Singapore, generates a territorialization of the city‐state such that it operates as a crack in the regulatory edifice of the Convention, even as Singapore lawfully fulfils its obligations to it. Moreover, allegations premised on the role of Singapore as a facilitator of global e‐waste dumping misrepresent its crucial role as a conduit of electronic equipment for the significant reuse markets elsewhere in Southeast Asia and beyond. The case indicates that the allegations against Singapore hinge on the city‐state being territorialized as a ‘developing country’
Appetite, gut hormone and energy intake responses to low volume sprint interval and traditional endurance exercise.
Sprint interval exercise improves several health markers but the appetite and energy balance response is unknown. This study compared the effects of sprint interval and endurance exercise on appetite, energy intake and gut hormone responses. Twelve healthy males [mean (SD): age 23 (3) years, body mass index 24.2 (2.9) kg m(-2), maximum oxygen uptake 46.3 (10.2) mL kg(-1) min(-1)] completed three 8 h trials [control (CON), endurance exercise (END), sprint interval exercise (SIE)] separated by 1 week. Trials commenced upon completion of a standardised breakfast. Sixty minutes of cycling at 68.1 (4.3) % of maximum oxygen uptake was performed from 1.75-2.75 h in END. Six 30-s Wingate tests were performed from 2.25-2.75 h in SIE. Appetite ratings, acylated ghrelin and peptide YY (PYY) concentrations were measured throughout each trial. Food intake was monitored from buffet meals at 3.5 and 7 h and an overnight food bag. Appetite (P 0.05). Therefore, relative energy intake (energy intake minus the net energy expenditure of exercise) was lower in END than that in CON (15.7 %; P = 0.006) and SIE (11.5 %; P = 0.082). An acute bout of endurance exercise resulted in lower appetite perceptions in the hours after exercise than sprint interval exercise and induced a greater 24 h energy deficit due to higher energy expenditure during exercise
Adverse prognostic and predictive significance of low DNA-dependent protein kinase catalytic subunit (DNA-PKcs) expression in early-stage breast cancers
Background: DNA-dependent protein kinase catalytic subunit (DNA-PKcs), a serine threonine kinase belonging to the PIKK family (phosphoinositide 3-kinase-like-family of protein kinase), is a critical component of the non-homologous end joining (NHEJ) pathway required for the repair of DNA double strand breaks. DNA-PKcs may be involved in breast cancer pathogenesis. Methods: We evaluated clinicopathological significance of DNA-PKcs protein expression in 1161 tumours and DNA-PKcs mRNA expression in 1950 tumours. We correlated DNA-PKcs to other markers of aggressive phenotypes, DNA repair, apoptosis and cell cycle regulation. Results: Low DNA-PKcs protein expression was associated with higher tumour grade, higher mitotic index, tumour de-differentiation and tumour type (ps<0.05). Absence of BRCA1, low XRCC1/SMUG1/APE1/Polβ were also more likely in low DNA-PKcs expressing tumours (ps<0.05). Low DNA-PKcs protein expression was significantly associated with worse breast cancer specific survival (BCCS) in univariate and multivariate analysis (ps<0.01). At the mRNA level, low DNA-PKcs was associated with PAM50.Her2 and PAM50.LumA molecular phenotypes (ps<0.01) and poor BCSS. In patients with ER positive tumours who received endocrine therapy, low DNA-PKcs (protein and mRNA) was associated with poor survival. In ER negative patients, low DNA-PKcs mRNA remains significantly associated with adverse outcome. Conclusions: Our study suggests that low DNA-PKcs expression may have prognostic and predictive significance in breast cancers
Brownian bridges to submanifolds
We introduce and study Brownian bridges to submanifolds. Our method involves
proving a general formula for the integral over a submanifold of the minimal
heat kernel on a complete Riemannian manifold. We use the formula to derive
lower bounds, an asymptotic relation and derivative estimates. We also see a
connection to hypersurface local time. This work is motivated by the desire to
extend the analysis of path and loop spaces to measures on paths which
terminate on a submanifold
A study of the benefits of retrofitting cardiovascular exercise equipment of a gym with human energy harvesting technology
Gemstone Team HEAT (Human Energy Acquisition Technology)This study seeks to identify the benefits of implementing human energy harvesting technology in gym exercise equipment. The central premise is that work put into fitness equipment by gym members can be used to generate electricity for the gym. This supplemental energy source can reduce the gym's overall need for electricity, therefore enhancing the gym as a green gym similar to the way of other alternative energy sources. The study includes an analysis of consumer preferences using detailed survey questionnaires, as well as an investigation of energy efficiency of gym establishments. Moreover, the feasibility of implementing this technology was evaluated from the standpoint of a business plan. By exploring the issue of a green gym from each of these three perspectives, this research shows that retrofitting a gym with energy harvesting technology can successfully enhance the image of the gym while making its operations more profitable
Strong Interactions of Single Atoms and Photons near a Dielectric Boundary
Modern research in optical physics has achieved quantum control of strong
interactions between a single atom and one photon within the setting of cavity
quantum electrodynamics (cQED). However, to move beyond current
proof-of-principle experiments involving one or two conventional optical
cavities to more complex scalable systems that employ N >> 1 microscopic
resonators requires the localization of individual atoms on distance scales <
100 nm from a resonator's surface. In this regime an atom can be strongly
coupled to a single intracavity photon while at the same time experiencing
significant radiative interactions with the dielectric boundaries of the
resonator. Here, we report an initial step into this new regime of cQED by way
of real-time detection and high-bandwidth feedback to select and monitor single
Cesium atoms localized ~100 nm from the surface of a micro-toroidal optical
resonator. We employ strong radiative interactions of atom and cavity field to
probe atomic motion through the evanescent field of the resonator. Direct
temporal and spectral measurements reveal both the significant role of
Casimir-Polder attraction and the manifestly quantum nature of the atom-cavity
dynamics. Our work sets the stage for trapping atoms near micro- and
nano-scopic optical resonators for applications in quantum information science,
including the creation of scalable quantum networks composed of many
atom-cavity systems that coherently interact via coherent exchanges of single
photons.Comment: 8 pages, 5 figures, Supplemental Information included as ancillary
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