Five Younger Dryas black mats in Mexico and their stratigraphic and paleoenvironmental context

The Younger Dryas interval (YD) was a period of widespread, abrupt climate change that occurred between 12,900 and 11,700 cal yr BP (10,900–10,000 14 C BP). Many sites in the Northern Hemisphere preserve a sedimentary record across the onset of the YD interval, including sites investigated in sedimentary basins located in central Mexico (Chapala, Cuitzeo, Acambay), the Basin of Mexico (Tocuila), and northern Mexico (El Cedral). Deposits consist of lacustrine or marginal lake sediments that were deposited during the Pleistocene and the Holocene. At the Tocuila and Acambay sites, Pleistocene fossil vertebrate assemblages, mainly mammoths (Mammuthus columbi), are found in association with a distinctive organic layer, sometimes called the black mat that formed during the YD. At the Chapala, Cuitzeo, Acambay, and Tocuila sites the black mats contain a suite of distinctive microscopic and mineralogical signatures and are accompanied by a sharp change in the depositional environments as supported by diatom and pollen studies reported here. The signatures include magnetic, Fe-rich microspherules, silica melted droplets with aerodynamic shapes (tektites), large amounts of charcoal, and sometimes nanodiamonds (Cuitzeo), all of which were deposited at the onset of the YD. The geochemistry of the microspherules indicates that they are not anthropogenic, authigenic or of cosmic or volcanic origin, and instead, were produced by melting and quenching of terrestrial sediments. Here, we present the stratigraphy at five field sites, the analyses of magnetic microspherules, including major element composition and scanning electron microscopy images. All of these materials are associated with charcoal and soot, which are distinctive stratigraphic markers for the YD layer at several sites in Mexico. © 2017 Springer Science+Business Media B.V

Fluorodeoxyglucose positron emission tomography in the evaluation of germ cell tumours at relapse

Differentiation of active disease from fibrosis/mature teratoma in patients with residual masses or identifying of sites of recurrence in patients with raised markers following treatment of their testicular cancer remains a problem.18F-fluorodeoxyglucose positron emission tomography (FDG-PET) has the potential to identify active disease and thereby influence further management in these patients. We performed a retrospective study of the use of FDG-PET in detecting residual/recurrent testicular carcinoma in 55 patients (seventy FDG-PET scans). Forty-seven scans were for the assessment of residual masses (18 had raised markers) and 23 scans were for the investigation of raised markers in the presence of normal CT scans. True positive results were based on positive histology or clinical follow-up. FDG-PET had a positive predictive value (PPV) of 96% and a negative predictive value (NPV) of 90% in patients with residual masses. This PPV was equivalent to that of markers (94%) but FDG-PET had the advantage of identifying the site of that recurrence. The NPV was higher than that of markers. In patients with raised markers alone the PPV of FDG-PET was 92% but the NPV was only 50%. However, subsequent FDG-PET imaging was frequently the first imaging modality to identify the site of disease. FDG-PET effected a management change in 57% of cases. FDG-PET scanning detected viable tumour in residual masses and identified sites of disease in suspected recurrence. © 2000 Cancer Research Campaig

Position-dependent stability and lifetime of the skyrmion state in nickel-substituted Cu2OSeO3

We report spatially resolved small-angle neutron-scattering measurements of the conical and skyrmion states of a bulk single crystal of nickel-substituted Cu2OSeO3, with a nominal concentration of Ni of 14%. We observe a significant spatial dependence of the structure of these magnetic states, characterized by increased disorder and misalignment with respect to the applied field as we approach the edge of the sample. Remarkably, the edge skyrmion state is also characterized by an extended stability towards lower temperatures. Surprisingly, in the same region of the sample, the metastable skyrmion state did not show simple decay. Instead, only a fraction of the scattered intensity appeared to decay, and the intensity therefore did not approach zero during our measurements. We suggest that the increased local disorder and the coexistence of conical and skyrmion states, induced by demagnetization effects at the edge of the sample, are responsible for the increased stability of this skyrmion state. We also infer that the unclear metastable behavior of the skyrmion lattice at the edge of the sample is due to the local geometry of the sample, which induces coexistence of different skyrmion states whose lifetimes are superimposed and difficult to separate in the data

Feasibility of tumour-focused adaptive radiotherapy for bladder cancer on the MR-linac.

Bladder tumour-focused magnetic resonance image-guided adaptive radiotherapy using a 1.5 Tesla MR-linac is feasible. A full online workflow adapting to anatomy at each fraction is achievable in approximately 30 min. Intra-fraction bladder filling did not compromise target coverage with the class solution employed

Magnetic resonance imaging sequence evaluation of an MR Linac system; early clinical experience.

Objectives:To systematically identify the preferred magnetic resonance imaging (MRI) sequences following volunteer imaging on a 1.5 Tesla (T) MR-Linear Accelerator (MR Linac) for future protocol development. Methods:Non-patient volunteers were recruited to a Research and Ethics committee approved prospective MR-only imaging study on a 1.5T MR Linac system. Volunteers attended 1-3 imaging sessions that included a combination of mDixon, T1w, T2w sequences using 2-dimensional (2D) and 3-dimensional (3D) acquisitions. Each sequence was acquired over 2-7 minutes and reviewed by a panel of 3 observers to evaluate image quality using a visual grading analysis based on a 4-point Likert scale. Sequences were acquired and modified iteratively until deemed fit for purpose (online image matching or re-planning) and all observers agreed they were suitable in 3 volunteers. Results:26 volunteers underwent 31 imaging sessions of six general anatomical regions. Images were acquired in one or two of six general anatomical regions: male pelvis (n = 9), female pelvis (n = 4), chestwall/breast (n = 5), lung/oesophagus (n = 5), abdomen (n = 3) and head and neck (n = 5). Images were acquired using a pre-defined exam-card that on average, included six sequences (range 2-10), with a maximum scan time of approximately one hour. The majority of observers preferred T2-weighted sequences. The thorax teams were the only groups to prefer T1-weighted imaging. Conclusions:An iterative process identified sequence agreement in all anatomical regions. These sequences will now be evaluated in patient volunteers. Advances in knowledge:This manuscript is the first publication sharing the results of the first systematic selection of MRI sequences for use in on-board MRI-guided radiotherapy by end-users (therapeutic radiographers and clinical oncologists) in healthy volunteers

Megahertz dynamics in skyrmion systems probed with muon-spin relaxation

We present longitudinal-field muon-spin relaxation (LF μ SR ) measurements on two systems that stabilize a skyrmion lattice (SkL): Cu 2 OSeO 3 , and Co x Zn y Mn 20 − x − y for ( x , y ) = ( 10 , 10 ) , (8, 9), and (8, 8). We find that the SkL phase of Cu 2 OSeO 3 exhibits emergent dynamic behavior at megahertz frequencies, likely due to collective excitations, allowing the SkL to be identified from the μ SR response. From measurements following different cooling protocols and calculations of the muon stopping site, we suggest that the metastable SkL is not the majority phase throughout the bulk of this material at the fields and temperatures where it is often observed. The dynamics of bulk Co 8 Zn 9 Mn 3 are well described by ≃ 2 GHz excitations that reduce in frequency near the critical temperature, while in Co 8 Zn 8 Mn 4 we observe similar behavior over a wide range of temperatures, implying that dynamics of this kind persist beyond the SkL phase

The human resource for health situation in Zambia: deficit and maldistribution

<p>Abstract</p> <p>Introduction</p> <p>Current health policy directions in Zambia are formulated in the National Health Strategic Plan. The Plan focuses on national health priorities, which include the human resources (HR) crisis. In this paper we describe the way the HRH establishment is distributed in the different provinces of Zambia, with a view to assess the dimension of shortages and of imbalances in the distribution of health workers by province and by level of care.</p> <p>Population and methods</p> <p>We used secondary data from the "March 2008 payroll data base", which lists all the public servants on the payroll of the Ministry of Health and of the National Health Service facilities. We computed rates and ratios and compared them.</p> <p>Results</p> <p>The highest relative concentration of all categories of workers was observed in Northern, Eastern, Lusaka, Western and Luapula provinces (in decreasing order of number of health workers).</p> <p>The ratio of clinical officers (mid-level clinical practitioners) to general medical officer (doctors with university training) varied from 3.77 in the Lusaka to 19.33 in the Northwestern provinces. For registered nurses (3 to 4 years of mid-level training), the ratio went from 3.54 in the Western to 15.00 in Eastern provinces and for enrolled nurses (two years of basic training) from 4.91 in the Luapula to 36.18 in the Southern provinces.</p> <p>This unequal distribution was reflected in the ratio of population per cadre. The provincial distribution of personnel showed a skewed staff distribution in favour of urbanized provinces, e.g. in Lusaka's doctor: population ratio was 1: 6,247 compared to Northern Province's ratio of 1: 65,763.</p> <p>In the whole country, the data set showed only 109 staff in health posts: 1 clinical officer, 3 environmental health technologists, 2 registered nurses, 12 enrolled midwives, 32 enrolled nurses, and 59 other.</p> <p>The vacancy rates for level 3 facilities(central hospitals, national level) varied from 5% in Lusaka to 38% in Copperbelt Province; for level 2 facilities (provincial level hospitals), from 30% for Western to 70% for Copperbelt Province; for level 1 facilities (district level hospitals), from 54% for the Southern to 80% for the Western provinces; for rural health centres, vacancies varied from 15% to 63% (for Lusaka and Luapula provinces respectively); for urban health centres the observed vacancy rates varied from 13% for the Lusaka to 96% for the Western provinces. We observed significant shortages in most staff categories, except for support staff, which had a significant surplus.</p> <p>Discussion and Conclusions</p> <p>This case study documents how a peaceful, politically stable African country with a longstanding tradition of strategic management of the health sector and with a track record of innovative approaches dealt with its HRH problems, but still remains with a major absolute and relative shortage of health workers. The case of Zambia reinforces the idea that training more staff is necessary to address the human resources crisis, but it is not sufficient and has to be completed with measures to mitigate attrition and to increase productivity.</p

The present and future of serum diagnostic tests for testicular germ cell tumours.

Testicular germ cell tumours (GCTs) are the most common malignancy occurring in young adult men and the incidence of these tumours is increasing. Current research priorities in this field include improving overall survival for patients classified as being 'poor-risk' and reducing late effects of treatment for patients classified as 'good-risk'. Testicular GCTs are broadly classified into seminomas and nonseminomatous GCTs (NSGCTs). The conventional serum protein tumour markers α-fetoprotein (AFP), human chorionic gonadotrophin (hCG) and lactate dehydrogenase (LDH) show some utility in the management of testicular malignant GCT. However, AFP and hCG display limited sensitivity and specificity, being indicative of yolk sac tumour (AFP) and choriocarcinoma or syncytiotrophoblast (hCG) subtypes. Furthermore, LDH is a very nonspecific biomarker. Consequently, seminomas and NSGCTs comprising a pure embryonal carcinoma subtype are generally negative for these conventional markers. As a result, novel universal biomarkers for testicular malignant GCTs are required. MicroRNAs are short, non-protein-coding RNAs that show much general promise as biomarkers. MicroRNAs from two 'clusters', miR-371-373 and miR-302-367, are overexpressed in all malignant GCTs, regardless of age (adult or paediatric), site (gonadal or extragonadal) and subtype (seminomas, yolk sac tumours or embryonal carcinomas). A panel of four circulating microRNAs from these two clusters (miR-371a-3p, miR-372-3p, miR-373-3p and miR-367-3p) is highly sensitive and specific for the diagnosis of malignant GCT, including seminoma and embryonal carcinoma. In the future, circulating microRNAs might be useful in diagnosis, disease monitoring and prognostication of malignant testicular GCTs, which might also reduce reliance on serial CT scanning. For translation into clinical practice, important practical considerations now need addressing.The authors would like to acknowledge grant funding from CwCUK/GOSHCC (M.J.M. N.C. grant W1058), SPARKS (M.J.M. N.C. grant 11CAM01), CRUK (N.C. grant A13080) MRC (M.J.M. grant MC_EX_G0800464) and National Health Service funding to the Royal Marsden/Institute of Cancer Research National Institute for Health Research Biomedical Research Centre for Cancer (R.A.H.). The authors also thank the Max Williamson Fund, the Josh Carrick Foundation and The Perse Preparatory School, Cambridge for support.This is the author accepted manuscript. The final version is available fromNature Publishing Group via https://doi.org/10.1038/nrurol.2016.17