2,862 research outputs found

    Lamellar Structures of MUC2-Rich Mucin: A Potential Role in Governing the Barrier and Lubricating Functions of Intestinal Mucus

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    Mucus is a ubiquitous feature of mammalian wet epithelial surfaces, where it lubricates and forms a selective barrier that excludes a range of particulates, including pathogens, while hosting a diverse commensal microflora. The major polymeric component of mucus is mucin, a large glycoprotein formed by several MUC gene products, with MUC2 expression dominating intestinal mucus. A satisfactory answer to the question of how these molecules build a dynamic structure capable of playing such a complex role has yet to be found, as recent reports of distinct layers of chemically identical mucin in the colon and anomalously rapid transport of nanoparticles through mucus have emphasized. Here we use atomic force microscopy (AFM) to image a MUC2-rich mucus fraction isolated from pig jejunum. In the freshly isolated mucin fraction, we find direct evidence for trigonally linked structures, and their assembly into lamellar networks with a distribution of pore sizes from 20 to 200 nm. The networks are two-dimensional, with little interaction between lamellae. The existence of persistent cross-links between individual mucin polypeptides is consistent with a non-self-interacting lamellar model for intestinal mucus structure, rather than a physically entangled polymer network. We only observe collapsed entangled structures in purified mucin that has been stored in nonphysiological conditions

    Feshbach resonances and collapsing Bose-Einstein condensates

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    We investigate the quantum state of burst atoms seen in the recent Rb-85 experiments at JILA. We show that the presence of a resonance scattering state can lead to a pairing instability generating an outflow of atoms with energy comparable to that observed. A resonance effective field theory is used to study this dynamical process in an inhomogeneous system with spherical symmetry

    Quasiparticle spectrum and dynamical stability of an atomic Bose-Einstein condensate coupled to a degenerate Fermi gas

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    The quasiparticle excitations and dynamical stability of an atomic Bose-Einstein condensate coupled to a quantum degenerate Fermi gas of atoms at zero temperature is studied. The Fermi gas is assumed to be either in the normal state or to have undergone a phase transition to a superfluid state by forming Cooper pairs. The quasiparticle excitations of the Bose-Einstein condensate exhibit a dynamical instability due to a resonant exchange of energy and momentum with quasiparticle excitations of the Fermi gas. The stability regime for the bosons depends on whether the Fermi gas is in the normal state or in the superfluid state. We show that the energy gap in the quasiparticle spectrum for the superfluid state stabilizes the low energy energy excitations of the condensate. In the stable regime, we calculate the boson quasiparticle spectrum, which is modified by the fluctuations in the density of the Fermi gas.Comment: 12 pages, 3 figure

    Water incident related hospital activity across England between 1997/8 and 2003/4: a retrospective descriptive study

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    Every year in the United Kingdom, 10,000 people will die from accidental injury and the treatment of these injuries will cost the NHS £2 billion and the consequences of injuries received at home cost society a further £25 billion [1]. Non-fatal injuries result in 720,000 people being admitted to hospital a year and more than six million visits to accident and emergency departments each year [2]. Drowning is the second leading cause of unintentional injury mortality globally behind road traffic injuries. It is estimated that a total of 409, 272 people drown each year [3]. This equates to a global incident rate of 7.4 deaths per 100, 000 people worldwide and relates to a further 1.3 million Disability Adjusted Life Years (DALYs) which are lost as a result of premature death or disability [4]. 'Death' represents only the tip of the injury "iceberg" [5]. For every life lost from an injury, many more people are admitted to hospital, attend accident and emergency departments or general practitioners, are rescued by search and rescue organisations or resolve the situation themselves. It is estimated that 1.3 million people are injured as a result of near drowning episodes globally and that many more hundreds of thousands of people are affected through incidents and near misses but there are no accurate data [4]. The United Kingdom has reported a variable drowning fatality rate, the injury chart book reports a rate of 1.0 – 1.5 per 100,000 [6] and other studies suggest a rate as low as 0.5 per 100, 000 population [7] for accidental drowning and submersion, based on the International Classification of Disease 10 code W65 – 74, however, the problem is even greater and these Global Burden of Disease (GDB) figures are an underestimate of all drowning deaths, since they exclude drownings due to cataclysms (floods), water related transport accidents, assaults and suicide [3]. A recent study in Scotland highlighted this underestimation in drowning fatality data and found that the overall death rate due to drownings in Scotland 3.26 per 100,000 [8]. Even though drowning fatality rates in the United Kingdom vary, little is known about the people who are admitted to hospital after an incident either in or on water. This paper seeks to address this gap in our knowledge through the investigation of the data available on those admitted to NHS hospitals in England

    Feshbach-Stimulated Photoproduction of a Stable Molecular Condensate

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    Photoassociation and the Feshbach resonance are, in principle, feasible means for creating a molecular Bose-Einstein condensate from an already-quantum-degenerate gas of atoms; however, mean-field shifts and irreversible decay place practical constraints on the efficient delivery of stable molecules using either mechanism alone. We therefore propose Feshbach-stimulated Raman photoproduction, i.e., a combination of magnetic and optical methods, as a viable means to collectively convert degenerate atoms into a stable molecular condensate with near-unit efficiency.Comment: 5 pages, 3 figures, 1 table; v3 includes few-level diagram of scheme, and added discussion; transferred to PR

    The projected impact of the COVID-19 lockdown on breast cancer deaths in England due to the cessation of population screening: a national estimation

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    BACKGROUND: Population breast screening services in England were suspended in March 2020 due to the COVID-19 pandemic. Here, we estimate the number of breast cancers whose detection may be delayed because of the suspension, and the potential impact on cancer deaths over 10 years. METHODS: We estimated the number and length of screening delays from observed NHS Breast Screening System data. We then estimated additional breast cancer deaths from three routes: asymptomatic tumours progressing to symptomatically diagnosed disease, invasive tumours which remain screen-detected but at a later date, and ductal carcinoma in situ (DCIS) progressing to invasive disease by detection. We took progression rates, prognostic characteristics, and survival rates from published sources. RESULTS: We estimated that 1,489,237 women had screening delayed by around 2–7 months between July 2020 and June 2021, leaving 745,277 outstanding screens. Depending on how quickly this backlog is cleared, around 2500–4100 cancers would shift from screen-detected to symptomatic cancers, resulting in 148–452 additional breast cancer deaths. There would be an additional 164–222 screen-detected tumour deaths, and 71–97 deaths from DCIS that progresses to invasive cancer. CONCLUSIONS: An estimated 148–687 additional breast cancer deaths may occur as a result of the pandemic-related disruptions. The impact depends on how quickly screening services catch up with delays
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