401 research outputs found

    An experimental study of two grave excavation methods: Arbitrary Level Excavation and Stratigraphic Excavation

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    The process of archaeological excavation is one of destruction. It normally provides archaeologists with a singular opportunity to recognise, define, extract and record archaeological evidence: the artefacts, features and deposits present in the archaeological record. It is expected that when archaeologists are excavating in a research, commercial or forensic setting the methods that they utilise will ensure a high rate of evidence recognition and recovery. Methods need to be accepted amongst the archaeological and scientific community they are serving and be deemed reliable. For example, in forensic contexts, methods need to conform to scientific and legal criteria so that the evidence retrieved is admissible in a court of law. Two standard methods of grave excavation were examined in this study with the aim of identifying the better approach in terms of evidence recovery. Four archaeologists with a range of experience each excavated two similarly constructed experimental ‘single graves’ using two different excavation methods. Those tested were the arbitrary level excavation method and the stratigraphic excavation method. The results from the excavations were used to compare recovery rates for varying forms of evidence placed within the graves. The stratigraphic excavation method resulted in higher rates of recovery for all evidence types, with an average of 71% of evidence being recovered, whereas the arbitrary level excavation method recovered an average of 56%. Neither method recovered all of the evidence. These findings raise questions about the reliability and so suitability of these established approaches to excavation

    Compromised Lactobacillus helveticus starter activity in the presence of facultative heterofermentative Lactobacillus casei DPC6987 results in atypical eye formation in Swiss-type cheese

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    peer-reviewedNonstarter lactic acid bacteria are commonly implicated in undesirable gas formation in several varieties, including Cheddar, Dutch-, and Swiss-type cheeses, primarily due to their ability to ferment a wide variety of substrates. This effect can be magnified due to factors that detrimentally affect the composition or activity of starter bacteria, resulting in the presence of greater than normal amounts of fermentable carbohydrates and citrate. The objective of this study was to determine the potential for a facultatively heterofermentative Lactobacillus (Lactobacillus casei DPC6987) isolated from a cheese plant environment to promote gas defects in the event of compromised starter activity. A Swiss-type cheese was manufactured, at pilot scale and in triplicate, containing a typical starter culture (Streptococcus thermophilus and Lactobacillus helveticus) together with propionic acid bacteria. Lactobacillus helveticus populations were omitted in certain vats to mimic starter failure. Lactobacillus casei DPC6987 was added to each experimental vat at 4 log cfu/g. Cheese compositional analysis and X-ray computed tomography revealed that the failure of starter bacteria, in this case L. helveticus, coupled with the presence of a faculatively heterofermentative Lactobacillus (L. casei) led to excessive eye formation during ripening. The availability of excess amounts of lactose, galactose, and citrate during the initial ripening stages likely provided the heterofermentative L. casei with sufficient substrates for gas formation. The accrual of these fermentable substrates was notable in cheeses lacking the L. helveticus starter population. The results of this study are commercially relevant, as they demonstrate the importance of viability of starter populations and the control of specific nonstarter lactic acid bacteria to ensure appropriate eye formation in Swiss-type cheese

    Evaluation of production of Cheddar cheese from micellar casein concentrate

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    peer-reviewedThe production of Cheddar cheese using micellar casein concentrate (MCC), a novel milk ingredient powder with a high casein content (∼92%), was evaluated. Four types of Cheddar cheese were manufactured and ripened for 180 days from the following starting materials: standardised control milk (control), skim milk with cream (SC), reconstituted MCC with cream (MC) and reconstituted low-heat skim milk powder with cream (PC). Only minor differences were found in composition between treatments, but MC cheese showed higher levels of proteolysis compared with other treatments, linked to significantly higher plasmin and chymosin activities. No differences were observed in hardness between treatments (60, 120 and 180 days), but the springiness and cohesiveness of MC and PC cheeses were significantly higher than that of the control and SC cheeses at 60, 120 and 180 days. The use of casein-dominant dairy streams thus has the potential for production of Cheddar cheese with tailored functionality.Department of Agriculture, Food and the Marine, Irelan

    Study of Thermal Properties of Graphene-Based Structures Using the Force Constant Method

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    The thermal properties of graphene-based materials are theoretically investigated. The fourth-nearest neighbor force constant method for phonon properties is used in conjunction with both the Landauer ballistic and the non-equilibrium Green's function techniques for transport. Ballistic phonon transport is investigated for different structures including graphene, graphene antidot lattices, and graphene nanoribbons. We demonstrate that this particular methodology is suitable for robust and efficient investigation of phonon transport in graphene-based devices. This methodology is especially useful for investigations of thermoelectric and heat transport applications.Comment: 23 pages, 9 figures, 1 tabl

    A replication study of genetic risk loci for ischemic stroke in a Dutch population: A case-control study

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    We aimed to replicate reported associations of 10 SNPs at eight distinct loci with overall ischemic stroke (IS) and its subtypes in an independent cohort of Dutch IS patients. We included 1,375 IS patients enrolled in a prospective multicenter hospital-based cohort in the Netherlands, and 1,533 population-level controls of Dutch descent. We tested these SNPs for association with overall IS and its subtypes (large artery atherosclerosis, small vessel disease and cardioembolic stroke (CE), as classified by TOAST) using an additive multivariable logistic regression model, adjusting for age and sex. We obtained odds ratios (OR) with 95% confidence intervals (95% CI) for the risk allele of each SNP analyzed and exact p-values by permutation. We confirmed the association at 4q25 (PITX2) (OR 1.43; 95% CI, 1.13-1.81, p = 0.029) and 16q22 (ZFHX3) (OR 1.62; 95% CI, 1.26-2.07, p = 0.001) as risk loci for CE. Locus 16q22 was also associated with overall IS (OR 1.24; 95% CI, 1.08-1.42, p = 0.016). Other loci previously associated with IS and/or its subtypes were not confirmed. In conclusion, we validated two loci (4q25, 16q22) associated with CE. In addition, our study may suggest that the association of locus 16q22 may not be limited to CE, but also includes overall IS

    Linear Response, Validity of Semi-Classical Gravity, and the Stability of Flat Space

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    A quantitative test for the validity of the semi-classical approximation in gravity is given. The criterion proposed is that solutions to the semi-classical Einstein equations should be stable to linearized perturbations, in the sense that no gauge invariant perturbation should become unbounded in time. A self-consistent linear response analysis of these perturbations, based upon an invariant effective action principle, necessarily involves metric fluctuations about the mean semi-classical geometry, and brings in the two-point correlation function of the quantum energy-momentum tensor in a natural way. This linear response equation contains no state dependent divergences and requires no new renormalization counterterms beyond those required in the leading order semi-classical approximation. The general linear response criterion is applied to the specific example of a scalar field with arbitrary mass and curvature coupling in the vacuum state of Minkowski spacetime. The spectral representation of the vacuum polarization function is computed in n dimensional Minkowski spacetime, and used to show that the flat space solution to the semi-classical Einstein equations for n=4 is stable to all perturbations on distance scales much larger than the Planck length.Comment: 22 pages: This is a significantly expanded version of gr-qc/0204083, with two additional sections and two new appendices giving a complete, explicit example of the semi-classical stability criterion proposed in the previous pape

    Benefits and barriers to expanding the availability of take-home naloxone in Australia: A qualitative interview study with service providers

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    Aims: To investigate the perspectives and experiences of service providers regarding provision of take-home naloxone to people who use opioids in Victoria, Australia. Methods: Content analysis of qualitative semi-structured interviews with 15 service providers who are either involved with take-home naloxone programs or whose work brings them in contact with people who use opioids. Findings: Statements about take-home naloxone were universally positive. Both direct and indirect benefits of take-home naloxone were described. Alongside potential reductions in opioid overdose-related harms, service providers highlighted the empowering effects of providing people who use opioids with take-home naloxone. No significant risks were described. Service providers supported the expansion of naloxone availability, but also identified several intertwined barriers to doing so. Key among these were costs, current regulations and scheduling, availability of prescribers and stigma related to illicit and injecting drug use. Conclusions: Expanding the availability of naloxone is a key component of strategies to reduce harms associated with opioid overdose. Our article provides Australian evidence of the successful operational implementation of peer-to-peer THN delivery within a range of drug primary health services and needle syringe programs. Further research is required to better understand the implications of and impediments to scale-up of this potentially life-saving public health intervention

    Ischemic brain lesions after carotid artery stenting increase future cerebrovascular risk

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    Background Brain lesions on diffusion-weighted imaging (DWI) are frequently found after carotid artery stenting (CAS), but their clinical relevance remains unclear. Objectives This study sought to investigate whether periprocedural ischemic DWI lesions after CAS or carotid endarterectomy (CEA) are associated with an increased risk of recurrent cerebrovascular events. Methods In the magnetic resonance imaging (MRI) substudy of ICSS (International Carotid Stenting Study), 231 patients with symptomatic carotid stenosis were randomized to undergo CAS (n = 124) or CEA (n = 107). MRIs were performed 1 to 7 days before and 1 to 3 days after treatment. The primary outcome event was stroke or transient ischemic attack in any territory occurring between the post-treatment MRI and the end of follow-up. Time to occurrence of the primary outcome event was compared between patients with (DWI+) and without (DWI-) new DWI lesions on the post-treatment scan in the CAS and CEA groups separately. Results Median time of follow-up was 4.1 years (interquartile range: 3.0 to 5.2). In the CAS group, recurrent stroke or transient ischemic attack occurred more often among DWI+ patients (12 of 62) than among DWI- patients (6 of 62), with a cumulative 5-year incidence of 22.8% (standard error [SE]: 7.1%) and 8.8% (SE: 3.8%), respectively (unadjusted hazard ratio: 2.85; 95% confidence interval: 1.05 to 7.72; p = 0.04). In DWI+ and DWI- patients, 8 and 2 events, respectively, occurred within 6 months after treatment. In the CEA group, there was no difference in recurrent cerebrovascular events between DWI+ and DWI- patients. Conclusions Ischemic brain lesions discovered on DWI after CAS seem to be a marker of increased risk for recurrent cerebrovascular events. Patients with periprocedural DWI lesions might benefit from more aggressive and prolonged antiplatelet therapy after CAS. (A Randomised Comparison of the Risks, Benefits and Cost Effectiveness of Primary Carotid Stenting With Carotid Endarterectomy: International Carotid Stenting Study; ISRCTN25337470

    Proof of the Julia-Zee Theorem

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    It is a well accepted principle that finite-energy static solutions in the classical relativistic gauge field theory over the (2+1)(2+1)-dimensional Minkowski spacetime must be electrically neutral. We call such a statement the Julia--Zee theorem. In this paper, we present a mathematical proof of this fundamental structural property

    Autophosphorylation-based calcium (Ca2+) sensitivity priming and Ca2+/Calmodulin inhibition of Arabidopsis thaliana Ca2+-dependent protein kinase 28 (CPK28)

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    Plant calcium (Ca2+) dependent protein kinases (CPKs) are composed of a dual specificity (Ser/Thr and Tyr) kinase domain tethered to a Calmodulin-like domain (CLD) via an autoinhibitory junction (J) and represent the primary Ca2+-dependent protein kinase activities in plant systems. While regulation of CPKs by Ca2+ has been extensively studied, the contribution of autophosphorylation in the control of CPK activity is less well understood. Furthermore, whether Calmodulin (CaM) contributes to CPK regulation, as is the case for Ca2+/CaM-dependent protein kinases (CaMKs) outside the plant lineage, remains an open question. We screened a subset of plant CPKs for CaM-binding and found that CPK28 is a high-affinity Ca2+/CaM-binding protein. Using synthetic peptides and native gel electrophoresis, we coarsely mapped the CaM-binding domain to a site within the CPK28 J domain that overlaps with the known site of intramolecular interaction between the J domain and CLD. Peptide kinase activity of fully dephosphorylated CPK28 was Ca2+-responsive and inhibited by Ca2+/CaM. Using in situ autophosphorylated protein, we expand on the known set of CPK28 autophosphorylation sites, and demonstrate that, unexpectedly, autophosphorylated CPK28 had enhanced activity at physiological concentrations of Ca2+ compared to dephosphorylated protein, suggesting that autophosphorylation functions to prime CPK28 for Ca2+-activation. Furthermore, CPK28 autophosphorylation substantially reduced sensitivity of the kinase to Ca2+/CaM inhibition. Overall, our analyses uncover new complexities in the control of CPK28 and provide mechanistic support for Ca2+ signaling specificity through Ca2+ sensor priming
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