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1.
Nature ; 590(7847): 566-570, 2021 02.
Artigo em Inglês | MEDLINE | ID: mdl-33627809

RESUMO

When a heavy atomic nucleus splits (fission), the resulting fragments are observed to emerge spinning1; this phenomenon has been a mystery in nuclear physics for over 40 years2,3. The internal generation of typically six or seven units of angular momentum in each fragment is particularly puzzling for systems that start with zero, or almost zero, spin. There are currently no experimental observations that enable decisive discrimination between the many competing theories for the mechanism that generates the angular momentum4-12. Nevertheless, the consensus is that excitation of collective vibrational modes generates the intrinsic spin before the nucleus splits (pre-scission). Here we show that there is no significant correlation between the spins of the fragment partners, which leads us to conclude that angular momentum in fission is actually generated after the nucleus splits (post-scission). We present comprehensive data showing that the average spin is strongly mass-dependent, varying in saw-tooth distributions. We observe no notable dependence of fragment spin on the mass or charge of the partner nucleus, confirming the uncorrelated post-scission nature of the spin mechanism. To explain these observations, we propose that the collective motion of nucleons in the ruptured neck of the fissioning system generates two independent torques, analogous to the snapping of an elastic band. A parameterization based on occupation of angular momentum states according to statistical theory describes the full range of experimental data well. This insight into the role of spin in nuclear fission is not only important for the fundamental understanding and theoretical description of fission, but also has consequences for the γ-ray heating problem in nuclear reactors13,14, for the study of the structure of neutron-rich isotopes15,16, and for the synthesis and stability of super-heavy elements17,18.

2.
Phys Rev Lett ; 132(12): 122701, 2024 Mar 22.
Artigo em Inglês | MEDLINE | ID: mdl-38579210

RESUMO

^{140}Ce(n,γ) is a key reaction for slow neutron-capture (s-process) nucleosynthesis due to being a bottleneck in the reaction flow. For this reason, it was measured with high accuracy (uncertainty ≈5%) at the n_TOF facility, with an unprecedented combination of a high purity sample and low neutron-sensitivity detectors. The measured Maxwellian averaged cross section is up to 40% higher than previously accepted values. Stellar model calculations indicate a reduction around 20% of the s-process contribution to the Galactic cerium abundance and smaller sizeable differences for most of the heavier elements. No variations are found in the nucleosynthesis from massive stars.

3.
Phys Rev Lett ; 130(20): 202501, 2023 May 19.
Artigo em Inglês | MEDLINE | ID: mdl-37267578

RESUMO

We demonstrate a new technique for obtaining fission data for nuclei away from ß stability. These types of data are pertinent to the astrophysical r process, crucial to a complete understanding of the origin of the heavy elements, and for developing a predictive model of fission. These data are also important considerations for terrestrial applications related to power generation and safeguarding. Experimentally, such data are scarce due to the difficulties in producing the actinide targets of interest. The solenoidal-spectrometer technique, commonly used to study nucleon-transfer reactions in inverse kinematics, has been applied to the case of transfer-induced fission as a means to deduce the fission-barrier height, among other variables. The fission-barrier height of ^{239}U has been determined via the ^{238}U(d,pf) reaction in inverse kinematics, the results of which are consistent with existing neutron-induced fission data indicating the validity of the technique.

4.
J Microsc ; 289(2): 107-127, 2023 02.
Artigo em Inglês | MEDLINE | ID: mdl-36399637

RESUMO

The correlative imaging workflow is a method of combining information and data across modes (e.g. SEM, X-ray CT, FIB-SEM), scales (cm to nm) and dimensions (2D-3D-4D), providing a more holistic interpretation of the research question. Often, subsurface objects of interest (e.g. inclusions, pores, cracks, defects in multilayered samples) are identified from initial exploratory nondestructive 3D tomographic imaging (e.g. X-ray CT, XRM), and those objects need to be studied using additional techniques to obtain, for example, 2D chemical or crystallographic data. Consequently, an intermediate sample preparation step needs to be completed, where a targeted amount of sample surface material is removed, exposing and revealing the object of interest. At present, there is not one singular technique for removing varied thicknesses at high resolution and on a range of scales from cm to nm. Here, we review the manual and automated options currently available for targeted sample material removal, with a focus on those methods which are readily accessible in most laboratories. We summarise the approaches for manual grinding and polishing, automated grinding and polishing, microtome/ultramicrotome, and broad-beam ion milling (BBIM), with further review of other more specialist techniques including serial block face electron microscopy (SBF-SEM), and ion milling and laser approaches such as FIB-SEM, Xe plasma FIB-SEM, and femtosecond laser/LaserFIB. We also address factors which may influence the decision on a particular technique, including the composition, shape and size of the samples, sample mounting limitations, the amount of surface material to be removed, the accuracy and/or resolution of peripheral parts, the accuracy and/or resolution of the technique/instrumentation, and other more general factors such as accessibility to instrumentation, costs, and the time taken for experimentation. It is hoped that this study will provide researchers with a range of options for removal of specific amounts of sample surface material to reach subsurface objects of interest in both correlative and non-correlative workflows.


Assuntos
Técnicas Histológicas , Imageamento Tridimensional , Microscopia Eletrônica de Varredura , Fluxo de Trabalho , Imageamento Tridimensional/métodos , Técnicas Histológicas/métodos , Microtomia
5.
J Chem Phys ; 156(16): 164701, 2022 Apr 28.
Artigo em Inglês | MEDLINE | ID: mdl-35490017

RESUMO

Sum-frequency generation (SFG) spectroscopy is frequently used to investigate the structure of monolayer films of long-chain fatty acids at the air-water interface. Although labeled a non-invasive technique, introducing intense SFG lasers onto liquid interfaces has the potential to perturb them. In the present work, narrowband picosecond SFG is used to study the structural changes that occur in palmitic acid and per-deuterated palmitic acid monolayers at the air-water interface in response to the high field strengths inherent to SFG spectroscopy. In order to determine structural changes and identify measurement artifacts, the changes in specific resonance intensities were measured in real-time and over a broad range of surface concentrations from films spread onto a stationary Langmuir trough. Using narrowband instead of broadband SFG minimizes the overlap of the incident infrared beam in the lipid C-H stretching region with resonances from the water sub-phase. Nevertheless, narrowband SFG still generates a thermal gradient at the surface, which produces a significant decrease in local concentration in the area of the laser spot caused by Bérnard-Marangoni convection originating in the sub-phase. The decrease in concentration results in an increase in the conformational disorder and a decrease in the tilt angle of lipid tails. Crucially, it is shown that, even at the highest monolayer concentrations, this gives rise to a measurement effect, which manifests itself as a dependence on the spectral acquisition time. This effect should be taken into account when interpreting the structure of monolayer films on liquid surfaces deduced from their SFG spectra.


Assuntos
Ar , Água , Ácido Palmítico , Análise Espectral , Propriedades de Superfície , Água/química
6.
Int J Cosmet Sci ; 44(1): 42-55, 2022 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-34820858

RESUMO

OBJECTIVE: The use of conventional microscopy and vibrational spectroscopy in the optical region to investigate the chemical nature of hair fibres on a nanometre scale is frustrated by the diffraction limit of light, prohibiting the spectral elucidation of nanoscale sub-structures that contribute to the bulk properties of hair. The aim of this work was to overcome this limitation and gain unprecedented chemical resolution of cortical cell nano-structure of hair. METHODS: The hybrid technique of AFM-IR, combining atomic force microscopy with an IR laser, circumvents the diffraction limit of light and achieves nanoscale chemical resolution down to the AFM tip radius. In this work, AFM-IR was employed on ultra-thin microtomed cross-sections of human hair fibres to spectrally distinguish and characterize the specific protein structures and environments within the nanoscale components of cortical cells. RESULTS: At first, a topographical and chemical distinction between the macrofibrils and the surrounding intermacrofibillar matrix was achieved based on 2.5 × 2.5 µm maps of cortical cell cross-sections. It was found that the intermacrofibrillar matrix has a large protein content and specific cysteine-related residues, whereas the macrofibrils showed bigger contributions from aliphatic amino acid residues and acidic-/ester-containing species (e.g. lipids). Localized spectra recorded at a spatial resolution of the order of the AFM tip radius enabled the chemical composition of each region to be determined following deconvolution of the Amide-I and Amide-II bands. This provided specific evidence for a greater proportion of α-helices in the macrofibrils and correspondingly larger contributions of ß-sheet secondary structures in the intermacrofibrillar matrix, as inferred in earlier studies. Analysis of the parallel and antiparallel ß-sheet structures, and of selected dominant amino acid residues, yielded further novel composition and conformation results for both regions. CONCLUSION: In this work, we overcome the diffraction limit of light using atomic force microscopy integrated with IR laser spectroscopy (AFM-IR) to characterize sub-micron features of the hair cortex at ultra-high spatial resolution. The resulting spectral analysis shows clear distinctions in the Amide bands in the macrofibrils and surrounding intermacrofibrillar matrix, yielding novel insight into the molecular structure and intermolecular stabilization interactions of the constituent proteins within each cortical component.


OBJECTIF: L'utilisation de la microscopie conventionnelle et de la spectroscopie vibratoire dans la région optique pour étudier la nature chimique des fibres capillaires à l'échelle nanométrique est limitée par la limite de diffraction de la lumière, interdisant l'élucidation spectrale des sous-structures à l'échelle nanométrique qui contribuent aux propriétés des cheveux en général. L'objectif de ce travail était de surmonter cette limitation et d'obtenir une résolution chimique sans précédent de la nanostructure cellulaire corticale des cheveux. MÉTHODES: La technique hybride de l'AFM-IR, combinant la microscopie à force atomique avec un laser IR, contourne la limite de diffraction de la lumière et permet d'obtenir une résolution chimique à l'échelle nanométrique jusqu'au rayon de l'extrémité de l'AFM. Dans ce travail, l'AFM-IR a été employée sur des coupes transversales microtomes ultrafines de fibres de cheveux humains pour distinguer et caractériser sur le plan spectral les structures et environnements protéiques spécifiques au sein des composants à l'échelle nanométrique des cellules corticales. RÉSULTATS: Tout d'abord, une distinction topographique et chimique entre les macrofibrilles et la matrice intermacrofibrillaire environnante a été obtenue à partir de cartes de 2,5 × 2,5 micromètres des coupes transversales des cellules corticales. Il a été constaté que la matrice intermacrofibrillaire avait une grande teneur en protéines et des résidus spécifiques liés à la cystéine, tandis que les macrofibrilles présentaient des contributions plus importantes provenant de résidus d'acides aminés aliphatiques et d'espèces acides/contenant des esters (p. ex. lipides). Les spectres localisés enregistrés à une résolution spatiale de l'ordre du rayon de l'extrémité AFM ont permis de déterminer la composition chimique de chaque région suite à la déconvolution des bandes Amide-I et Amide-II. Cela a apporté des preuves spécifiques pour une plus grande proportion des hélices alpha des macrofibrilles, de même que des contributions plus importantes des structures secondaires à feuillet bêta dans la matrice intermacrofibrillaire, déduites dans des études antérieures. L'analyse des structures parallèles et antiparallèles des feuillets bêta, et des résidus d'acides aminés dominants sélectionnés a donné des résultats inédits de composition et de conformation pour les deux régions. CONCLUSION: Dans ce travail, nous avons surmonté la limite de diffraction de la lumière en utilisant la microscopie à force atomique intégrée à la spectroscopie laser IR (IR-AFM) pour caractériser les caractéristiques submicroniques du cortex capillaire à une résolution spatiale ultra-élevée. L'analyse spectrale qui en résulte montre des distinctions nettes dans les bandes d'amide dans les macrofibrilles et la matrice intermacrofibrillaire environnante, ce qui apporte un éclairage nouveau sur la structure moléculaire et les interactions de stabilisation intermoléculaire des protéines constitutives dans chaque composant cortical.


Assuntos
Cabelo , Proteínas , Cabelo/química , Humanos , Microscopia de Força Atômica/métodos , Estrutura Secundária de Proteína , Proteínas/análise , Espectrofotometria Infravermelho/métodos
7.
Phys Rev Lett ; 126(7): 072501, 2021 Feb 19.
Artigo em Inglês | MEDLINE | ID: mdl-33666458

RESUMO

We studied the proton-rich T_{z}=-1 nucleus ^{70}Kr through inelastic scattering at intermediate energies in order to extract the reduced transition probability, B(E2;0^{+}→2^{+}). Comparison with the other members of the A=70 isospin triplet, ^{70}Br and ^{70}Se, studied in the same experiment, shows a 3σ deviation from the expected linearity of the electromagnetic matrix elements as a function of T_{z}. At present, no established nuclear structure theory can describe this observed deviation quantitatively. This is the first violation of isospin symmetry at this level observed in the transition matrix elements. A heuristic approach may explain the anomaly by a shape change between the mirror nuclei ^{70}Kr and ^{70}Se contrary to the model predictions.

8.
Agric Syst ; 191: 103152, 2021 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-36570633

RESUMO

Context: Resilience is the ability to deal with shocks and stresses, including the unknown and previously unimaginable, such as the Covid-19 crisis. Objective: This paper assesses (i) how different farming systems were exposed to the crisis, (ii) which resilience capacities were revealed and (iii) how resilience was enabled or constrained by the farming systems' social and institutional environment. Methods: The 11 farming systems included have been analysed since 2017. This allows a comparison of pre-Covid-19 findings and the Covid-19 crisis. Pre-Covid findings are from the SURE-Farm systematic sustainability and resilience assessment. For Covid-19 a special data collection was carried out during the early stage of lockdowns. Results and conclusions: Our case studies found limited impact of Covid-19 on the production and delivery of food and other agricultural products. This was due to either little exposure or the agile activation of robustness capacities of the farming systems in combination with an enabling institutional environment. Revealed capacities were mainly based on already existing connectedness among farmers and more broadly in value chains. Across cases, the experience of the crisis triggered reflexivity about the operation of the farming systems. Recurring topics were the need for shorter chains, more fairness towards farmers, and less dependence on migrant workers. However, actors in the farming systems and the enabling environment generally focused on the immediate issues and gave little real consideration to long-term implications and challenges. Hence, adaptive or transformative capacities were much less on display than coping capacities. The comparison with pre-Covid findings mostly showed similarities. If challenges, such as shortage of labour, already loomed before, they persisted during the crisis. Furthermore, the eminent role of resilience attributes was confirmed. In cases with high connectedness and diversity we found that these system characteristics contributed significantly to dealing with the crisis. Also the focus on coping capacities was already visible before the crisis. We are not sure yet whether the focus on short-term robustness just reflects the higher visibility and urgency of shocks compared to slow processes that undermine or threaten important system functions, or whether they betray an imbalance in resilience capacities at the expense of adaptability and transformability. Significance: Our analysis indicates that if transformations are required, e.g. to respond to concerns about transnational value chains and future pandemics from zoonosis, the transformative capacity of many farming systems needs to be actively enhanced through an enabling environment.

9.
BMC Microbiol ; 20(1): 107, 2020 05 01.
Artigo em Inglês | MEDLINE | ID: mdl-32357840

RESUMO

BACKGROUND: Footrot and interdigital dermatitis are endemic infectious diseases in all sheep farming regions, impairing welfare and production. The development of efficacious vaccines against the primary causative pathogen has been hampered by the extensive antigenic diversity of Dichelobacter nodosus. Understanding the heterogeneity of the pathogen within and between flocks is essential if the feasibility of bespoke vaccine production is to be assessed for use in the U.K. RESULTS: In this study 56 ewe and lamb isolates from 9 flocks were compared by D. nodosus serogroup and Multi Locus Sequence Type which provides significantly enhanced discriminatory power for molecular epidemiology. Serogroup heterogeneity between flocks ranged from two to five unique serogroups per flock. Three flocks contained isolates of two serogroups, two flocks contained isolates of three serogroups and one flock included isolates of five serogroups. Analysis of 25 isolates from one flock with high prevalence of lameness, identified that serogroup and sequence type was significantly correlated with age. Significantly higher proportion of lambs were infected with serogroup B (principally ST85) as opposed to serogroup H (principally ST86), which predominated amongst adult sheep. CONCLUSIONS: Genomic heterogeneity of the pathogen was significantly lower within flock compared to heterogenicity observed between flocks. Furthermore, this study indicates that within a flock, the host-pathogen dynamics and susceptibility to particular D. nodosus strains may be age dependent.


Assuntos
Dichelobacter nodosus/classificação , Heterogeneidade Genética , Infecções por Bactérias Gram-Negativas/veterinária , Tipagem de Sequências Multilocus/métodos , Doenças dos Ovinos/microbiologia , Animais , Técnicas de Tipagem Bacteriana , Dichelobacter nodosus/genética , Dichelobacter nodosus/isolamento & purificação , Dermatite Digital/microbiologia , Feminino , Pododermatite Necrótica dos Ovinos/microbiologia , Infecções por Bactérias Gram-Negativas/microbiologia , Filogenia , Sorogrupo , Ovinos , Reino Unido
10.
Biomarkers ; 24(2): 127-130, 2019 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-30051724

RESUMO

BACKGROUND: Procalcitonin levels may be raised in bacterial infections and have been used to guide antibiotic therapy. There is little data on procalcitonin and limb cellulitis. OBJECTIVES: Within a clinical trial of antibiotic therapy, we examined the correlation between clinical observations, blood tests and local measurements of skin damage, with serum procalcitonin levels. METHODS: The data is from a subset of the patients recruited into a clinical trial of antibiotic therapy for cellulitis (clindamycin for cellulitis, NCT01876628) whose procalcitonin levels were correlated with clinical and laboratory measurements. We selected the variables strongly correlated with procalcitonin and evaluated the predictive value of the baseline procalcitonin on the primary trial outcome. RESULTS: 136 patients provided 307 procalcitonin levels which were correlated with 8 variables. The strongest correlations (correlation coefficient of >0.5) with procalcitonin were the affected skin area (0.537), C-reactive protein (0.574) and neutrophil:lymphocyte ratio (0.567). Receiver operator characteristic curves demonstrated poor sensitivity and specificity of procalcitonin in predicting primary outcome. Procalcitonin baseline levels were low but decreased as patients recovered. CONCLUSIONS: Procalcitonin levels are generally low in limb cellulitis and cannot be used to confirm the diagnosis or the need for antibiotic therapy. Procalcitonin is a poor predictor of early improvement.


Assuntos
Celulite (Flegmão)/sangue , Celulite (Flegmão)/tratamento farmacológico , Clindamicina/administração & dosagem , Pró-Calcitonina/sangue , Antibacterianos/administração & dosagem , Celulite (Flegmão)/patologia , Extremidades/fisiopatologia , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Pele/efeitos dos fármacos , Pele/fisiopatologia
12.
Faraday Discuss ; 208(0): 455-470, 2018 09 03.
Artigo em Inglês | MEDLINE | ID: mdl-29845183

RESUMO

The enormous complexity of a typical heterogeneous catalyst makes understanding the development and properties of any active nanoparticles present extremely challenging. In the case of carbon based catalysts that difficulty is compounded by the variability of the carbon powders used. We have previously developed a strategy that addresses these problems by mimicking the catalyst preparation conditions very closely but using highly ordered pyrolytic graphite crystals (HOPG) as a model surface. This enables us to examine the effects of specific functional groups on nanoparticle formation. We report here an extension of our work characterising functional groups on the HOPG surface, using XPS and AFM to explore the deposition of gold from aqueous solution onto HOPG surfaces treated in a variety of ways to alter the surface functionality. The structure and oxidation state of the resulting nanoparticles depend critically on the nature of the functional groups present and offers some insight into the development of catalysts based on these materials. Hydroxyls are identified as key functional species, reducing gold ions to their metallic state whilst being oxidised themselves to carbonyls. Carbonyls meanwhile promote the nucleation of Au3+, creating a network of islands at the HOPG surface. The results have relevance not only to catalysts using activated carbons but also the new generation of materials based on graphene and carbon nanotubes.

13.
J Acoust Soc Am ; 143(1): 489, 2018 01.
Artigo em Inglês | MEDLINE | ID: mdl-29390778

RESUMO

The effects of perceptible whole-body vibrations on annoyance ratings of sonic booms and other impulsive environmental sounds experienced indoors were studied. Fifteen pairs of test subjects made annoyance ratings while seated in a living room environment. There were two chairs, one isolated from floor vibrations and the other not isolated, and every test subject rated all signals in both chairs. Halfway through each test session, subjects changed seats. Subjects who sat in the isolated chair first gave lower mean annoyance ratings in both halves of the test than subjects who sat in the non-isolated chair first. Annoyance predictions from models using both sound and vibration measures were closer to average annoyance ratings than predictions from a model using sound measures alone. Reformulation of the annoyance model revealed that the presence of perceptible vibration is equivalent to increasing acoustic metric Perceived Level by 4.8 dB when calculated on exterior signals and by 5.6 dB when calculated on interior signals.

14.
Surgeon ; 16(4): 227-231, 2018 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-29248360

RESUMO

INTRODUCTION: 10-year study examining differences in total knee arthroplasty (TKA) functional outcomes and survivorship in patients operated on by consultant and trainee orthopaedic surgeons. METHOD: Data was prospectively collected from all elective TKAs performed at our three linked institutions. Patient demographics, surgeon grade, and length of hospital stay were recorded. Outcomes pre-operatively and at 1, 3, 5, 7 and 10 years included mortality, need for revision surgery and function as documented by the patients' Knee Society Score. RESULTS: 686 patients were included in the study. 450 (65.5%) patients were operated by consultant surgeons and 236 (34.4%) by trainees. On multivariate analysis no significant differences were observed between groups in length of hospital stay (p = 0.695), implant survival (p = 0.422), and function (p = 0.507) at 10 years. On Cox regression analysis no significant difference was observed in mortality (p = 0.209) at 10 years. 4 patients over this time period were lost to formal follow up. CONCLUSION: No significant difference was observed in the TKA outcomes between consultants and trainees 10 years post-operatively.


Assuntos
Artroplastia do Joelho/educação , Artroplastia do Joelho/normas , Artropatias/cirurgia , Articulação do Joelho/cirurgia , Adulto , Idoso , Idoso de 80 Anos ou mais , Humanos , Prótese do Joelho , Pessoa de Meia-Idade , Resultado do Tratamento
15.
Phys Rev Lett ; 119(19): 192503, 2017 Nov 10.
Artigo em Inglês | MEDLINE | ID: mdl-29219499

RESUMO

In this Letter, the observation of two previously unknown isotopes is presented for the first time: ^{72}Rb with 14 observed events and ^{77}Zr with one observed event. From the nonobservation of the less proton-rich nucleus ^{73}Rb, we derive an upper limit for the ground-state half-life of 81 ns, consistent with the previous upper limit of 30 ns. For ^{72}Rb, we have measured a half-life of 103(22) ns. This observation of a relatively long-lived odd-odd nucleus, ^{72}Rb, with a less exotic odd-even neighbor, ^{73}Rb, being unbound shows the diffuseness of the proton drip line and the possibility of sandbanks to exist beyond it. The ^{72}Rb half-life is consistent with a 5^{+}→5/2^{-} proton decay with an energy of 800-900 keV, in agreement with the atomic mass evaluation proton-separation energy as well as results from the finite-range droplet model and shell model calculations using the GXPF1A interaction. However, we cannot explicitly exclude the possibility of a proton transition between 9^{+}(^{72}Rb)→9/2^{+}(^{71}Kr) isomeric states with a broken mirror symmetry. These results imply that ^{72}Kr is a strong waiting point in x-ray burst rp-process scenarios.

16.
Nature ; 469(7328): 68-71, 2011 Jan 06.
Artigo em Inglês | MEDLINE | ID: mdl-21179086

RESUMO

Shell structure and magic numbers in atomic nuclei were generally explained by pioneering work that introduced a strong spin-orbit interaction to the nuclear shell model potential. However, knowledge of nuclear forces and the mechanisms governing the structure of nuclei, in particular far from stability, is still incomplete. In nuclei with equal neutron and proton numbers (N = Z), enhanced correlations arise between neutrons and protons (two distinct types of fermions) that occupy orbitals with the same quantum numbers. Such correlations have been predicted to favour an unusual type of nuclear superfluidity, termed isoscalar neutron-proton pairing, in addition to normal isovector pairing. Despite many experimental efforts, these predictions have not been confirmed. Here we report the experimental observation of excited states in the N = Z = 46 nucleus (92)Pd. Gamma rays emitted following the (58)Ni((36)Ar,2n)(92)Pd fusion-evaporation reaction were identified using a combination of state-of-the-art high-resolution γ-ray, charged-particle and neutron detector systems. Our results reveal evidence for a spin-aligned, isoscalar neutron-proton coupling scheme, different from the previous prediction. We suggest that this coupling scheme replaces normal superfluidity (characterized by seniority coupling) in the ground and low-lying excited states of the heaviest N = Z nuclei. Such strong, isoscalar neutron-proton correlations would have a considerable impact on the nuclear level structure and possibly influence the dynamics of rapid proton capture in stellar nucleosynthesis.

17.
Matern Child Health J ; 21(1): 215-221, 2017 01.
Artigo em Inglês | MEDLINE | ID: mdl-27514390

RESUMO

Introduction Appropriate dietary iodine is essential for thyroid hormone synthesis, especially in young children. Following an iodine fortification in bread initiative, approximately 6 % of Australian preschool children were expected to have an excessive iodine status. The aim of this study was to document the current iodine status of preschool children using urinary iodine concentration (UIC) as a biomarker of iodine intake. Methods A convenience sample of fifty-one preschool children, aged 2-3 years, were recruited from south east Queensland. UIC was ascertained from spot morning and afternoon urine samples collected on two consecutive days and food frequency questionnaires were completed for each participant. Dietary iodine intake was extrapolated from UIC assuming 90 % of dietary iodine is excreted in urine and a urine volume of 0.5 L/day. Results A median UIC of 223.3 µg/L was found. The calculated median dietary iodine intake was 124.8 µg/day (SD 47.0) with 9.8 % of samples above the upper level of 200 µg for dietary iodine for children within this age group. No foods were associated with UIC. Discussion Limited by sample size and recruitment strategies, no association was found between usual food intake and UIC. Extrapolated dietary iodine intake indicated that children within this cohort consumed adequate amounts of dietary iodine, although the number of children consuming above the upper limit of 300 µg/day was almost double of expected. The development of a UIC criteria to assess appropriate parameters for varying degrees of iodine status is required for the monitoring of iodine nutrition in this vulnerable age group.


Assuntos
Pão/estatística & dados numéricos , Alimentos Fortificados/estatística & dados numéricos , Iodo/administração & dosagem , Ciências da Nutrição Infantil/tendências , Pré-Escolar , Comportamento Alimentar , Humanos , Iodo/análise , Iodo/urina , Saúde Pública/métodos , Queensland , Inquéritos e Questionários
18.
Environ Monit Assess ; 189(8): 408, 2017 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-28733784

RESUMO

The extraction of coal and coal seam gas (CSG) will generate produced water that, if not adequately treated, will pollute surface and groundwater systems. In Australia, the discharge of produced water from coal mining and related activities is regulated by the state environment agency through a pollution licence. This licence sets the discharge limits for a range of analytes to protect the environment into which the produced water is discharged. This study reports on the impact of produced water from coal mine activities located within or discharging into high conservation environments, such as National Parks, in the outer region of Sydney, Australia. The water samples upstream and downstream from the discharge points from six mines were taken, and 110 parameters were tested. The results were assessed against a water quality index (WQI) which accounts for pH, turbidity, dissolved oxygen, biochemical oxygen demand, total dissolved solids, total phosphorus, nitrate nitrogen and E .coli. The water quality assessment based on the trace metal contents against various national maximum admissible concentration (MAC) and their corresponding environmental impacts was also included in the study which also established a base value of water quality for further study. The study revealed that impacted water downstream of the mine discharge points contained higher metal content than the upstream reference locations. In many cases, the downstream water was above the Australia and New Zealand Environment Conservation Council and international water quality guidelines for freshwater stream. The major outliers to the guidelines were aluminium (Al), iron (Fe), manganese (Mn), nickel (Ni) and zinc (Zn). The WQI of surface water at and downstream of the discharge point was lower when compared to upstream or reference conditions in the majority of cases. Toxicology indices of metals present in industrial discharges were used as an additional tool to assess water quality, and the newly proposed environmental water quality index (EWQI) lead to better trend in the impact of coal and coal seam gas mining activities on surface water quality when compared to the upstream reference water samples. Metal content limits were based on the impact points assigned by the Agency for Toxic Substances and Disease Registry, USA. For environmental and health impact assessment, the approach used in this study can be applied as a model to provide a basis to assess the anthropogenic contribution from the industrial and mining activities on the environment.


Assuntos
Minas de Carvão , Monitoramento Ambiental , Poluentes Químicos da Água/análise , Qualidade da Água , Carvão Mineral/análise , Meio Ambiente , Água Doce/química , Água Subterrânea/química , Ferro , Metais , New South Wales , Água , Zinco
19.
Aust J Prim Health ; 23(2): 107-113, 2017 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-28442054

RESUMO

Developed nations are implementing initiatives to transform the delivery of primary care. New models have been built around multidisciplinary teams, information technology and systematic approaches for chronic disease management (CDM). In Australia, the General Practice Super Clinic (GPSC) model was introduced in 2010. A case study approach was used to illustrate the development of inter-disciplinary CDM over 12 months in two new, outer urban GPSCs. A social scientist visited each practice for two 3-4-day periods. Data, including practice documents, observations and in-depth interviews (n=31) with patients, clinicians and staff, were analysed using the concept of organisational routines. Findings revealed slow, incremental evolution of inter-disciplinary care in both sites. Clinic managers found the facilitation of inter-disciplinary routines for CDM difficult in light of competing priorities within program objectives and the demands of clinic construction. Constraints inherent within the GPSC program, a lack of meaningful support for transformation of the model of care and the lack of effective incentives for collaborative care in fee-for-service billing arrangements, meant that program objectives for integrated multidisciplinary care were largely unattainable. Findings suggest that the GPSC initiative should be considered a program for infrastructure support rather than one of primary care transformation.


Assuntos
Medicina Geral/organização & administração , Modelos Organizacionais , Humanos , Entrevistas como Assunto , New South Wales , Estudos de Casos Organizacionais , Inovação Organizacional , Objetivos Organizacionais , Vitória
20.
J Clin Microbiol ; 54(1): 68-74, 2016 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-26491180

RESUMO

Multilocus sequence typing was successfully completed on 494 isolates of Streptococcus uberis from clinical mastitis cases in a study of 52 commercial dairy herds over a 12-month period. In total, 195 sequence types (STs) were identified. S. uberis mastitis cases that occurred in different cows within the same herd and were attributed to a common ST were classified as potential transmission events (PTEs). Clinical cases attributed to 35 of the 195 STs identified in this study were classified PTE. PTEs were identified in 63% of the herds. PTE-associated cases, which include the first recorded occurrence of that ST in that herd (index case) and all persistent infections with that PTE ST, represented 40% of all the clinical mastitis cases and occurred in 63% of the herds. PTE-associated cases accounted for >50% of all S. uberis clinical mastitis cases in 33% of the herds. Nine STs (ST-5, -6, -20, -22, -24, -35, -233, -361, and -512), eight of which were grouped within a clonal complex (sharing at least four alleles), were statistically overrepresented (OVR STs). The findings indicate that 38% of all clinical mastitis cases and 63% of the PTEs attributed to S. uberis in dairy herds may be caused by the nine most prevalent strains. The findings suggest that a small subset of STs is disproportionally important in the epidemiology of S. uberis mastitis in the United Kingdom, with cow-to-cow transmission of S. uberis potentially occurring in the majority of herds in the United Kingdom, and may be the most important route of infection in many herds.


Assuntos
Transmissão de Doença Infecciosa , Variação Genética , Mastite Bovina/epidemiologia , Mastite Bovina/transmissão , Infecções Estreptocócicas/veterinária , Streptococcus/classificação , Streptococcus/isolamento & purificação , Animais , Bovinos , Mastite Bovina/microbiologia , Epidemiologia Molecular , Tipagem de Sequências Multilocus , Infecções Estreptocócicas/epidemiologia , Infecções Estreptocócicas/microbiologia , Infecções Estreptocócicas/transmissão , Streptococcus/genética , Reino Unido/epidemiologia
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