4,637 research outputs found
Quantifying the effect of interannual ocean variability on the attribution of extreme climate events to human influence
In recent years, the climate change research community has become highly
interested in describing the anthropogenic influence on extreme weather events,
commonly termed "event attribution." Limitations in the observational record
and in computational resources motivate the use of uncoupled,
atmosphere/land-only climate models with prescribed ocean conditions run over a
short period, leading up to and including an event of interest. In this
approach, large ensembles of high-resolution simulations can be generated under
factual observed conditions and counterfactual conditions that might have been
observed in the absence of human interference; these can be used to estimate
the change in probability of the given event due to anthropogenic influence.
However, using a prescribed ocean state ignores the possibility that estimates
of attributable risk might be a function of the ocean state. Thus, the
uncertainty in attributable risk is likely underestimated, implying an
over-confidence in anthropogenic influence.
In this work, we estimate the year-to-year variability in calculations of the
anthropogenic contribution to extreme weather based on large ensembles of
atmospheric model simulations. Our results both quantify the magnitude of
year-to-year variability and categorize the degree to which conclusions of
attributable risk are qualitatively affected. The methodology is illustrated by
exploring extreme temperature and precipitation events for the northwest coast
of South America and northern-central Siberia; we also provides results for
regions around the globe. While it remains preferable to perform a full
multi-year analysis, the results presented here can serve as an indication of
where and when attribution researchers should be concerned about the use of
atmosphere-only simulations
Metagenomic analysis of dental calculus in ancient Egyptian baboons
Dental calculus, or mineralized plaque, represents a record of ancient biomolecules and food residues. Recently, ancient metagenomics made it possible to unlock the wealth of microbial and dietary information of dental calculus to reconstruct oral microbiomes and lifestyle of humans from the past. Although most studies have so far focused on ancient humans, dental calculus is known to form in a wide range of animals, potentially informing on how human-animal interactions changed the animals' oral ecology. Here, we characterise the oral microbiome of six ancient Egyptian baboons held in captivity during the late Pharaonic era (9th-6th centuries BC) and of two historical baboons from a zoo via shotgun metagenomics. We demonstrate that these captive baboons possessed a distinctive oral microbiome when compared to ancient and modern humans, Neanderthals and a wild chimpanzee. These results may reflect the omnivorous dietary behaviour of baboons, even though health, food provisioning and other factors associated with human management, may have changed the baboons' oral microbiome. We anticipate our study to be a starting point for more extensive studies on ancient animal oral microbiomes to examine the extent to which domestication and human management in the past affected the diet, health and lifestyle of target animals
Evaluation--Making it Real in Aotearoa New Zealand: Leading by Example, Leading by Association
The second Aotearoa New Zealand Evaluation Conference, sponsored by the Auckland Evaluation Group, will be held 18-20 July, 2005 at the Tauhara Centre, Acacia Bay, Taupo
Using all transverse degrees of freedom in quantum communications based on a generic mode sorter
The dimension of the state space for information encoding offered by the
transverse structure of light is usually limited by the finite size of
apertures. The widely used orbital angular momentum (OAM) number of
Laguerre-Gaussian (LG) modes in free-space communications cannot achieve the
theoretical maximum transmission capacity unless the radial degree of freedom
is multiplexed into the protocol. While the methodology to sort the radial
quantum number has been developed, the application of radial modes in quantum
communications requires an additional ability to efficiently measure the
superposition of LG modes in the mutually unbiased basis. Here we develop and
implement a generic mode sorter that is capable of sorting the superposition of
LG modes through the use of a mode converter. As a consequence, we demonstrate
an 8-dimensional quantum key distribution experiment involving all three
transverse degrees of freedom: spin, azimuthal, and radial quantum numbers of
photons. Our protocol presents an important step towards the goal of reaching
the capacity limit of a free-space link and can be useful to other applications
that involve spatial modes of photons
Precise scenarios - a customer-friendly foundation for formal specifications
A formal specification is beyond the comprehension of the average software customer. As a result, the customer cannot provide useful feedback regarding its correctness and completeness. To address this problem, we suggest the formalism expert to work with the customer to create precise scenarios. A precise scenario describes an operation by its effects on the system state with only few simple Z
concepts. The customer would find a concrete precise scenario easier to understand than its corresponding abstract schema. The Z expert derives schemas based on the precise scenarios. Precise scenarios affords user involvement that improves the odds of a formal specification fully capturing the user requirements
Cracking the Discovery Code
An alternative perspective of discovery services. What effect are they having on content usage at the
publisher site and is it the effect that you would expect? What are the common pitfalls and how can you
address them? Publishers, librarians and discovery service providers discuss
Developing fibre optic Raman probes for applications in clinical spectroscopy
Raman spectroscopy has been shown by various groups over the last two decades to have significant capability in discriminating disease states in bodily fluids, cells and tissues. Recent development in instrumentation, optics and manufacturing approaches has facilitated the design and demonstration of various novel in vivo probes, which have applicability for myriad of applications. This review focusses on key considerations and recommendations for application specific clinical Raman probe design and construction. Raman probes can be utilised as clinical tools able to provide rapid, non-invasive, real-time molecular analysis of disease specific changes in tissues. Clearly the target tissue location, the significance of spectral changes with disease and the possible access routes to the region of interest will vary for each clinical application considered. This review provides insight into design and construction considerations, including suitable probe designs and manufacturing materials compatible with Raman spectroscopy
Glutamate, N-acetyl aspartate and psychotic symptoms in chronic ketamine users
Rationale:
Ketamine, a non-competitive NMDA receptor antagonist, induces acute effects resembling the positive, negative and cognitive symptoms of schizophrenia. Chronic use has been suggested to lead to persistent schizophrenia-like neurobiological changes.
Objectives:
This study aims to test the hypothesis that chronic ketamine users have changes in brain neurochemistry and increased subthreshold psychotic symptoms compared to matched poly-drug users.
Methods:
Fifteen ketamine users and 13 poly-drug users were included in the study. Psychopathology was assessed using the Comprehensive Assessment of At-Risk Mental State. Creatine-scaled glutamate (Glu/Cr), glutamate + glutamine (Glu + Gln/Cr) and N-acetyl aspartate (NAA/Cr) were measured in three brain regions—anterior cingulate, left thalamus and left medial temporal cortex using proton magnetic resonance spectroscopy.
Results:
Chronic ketamine users had higher levels of subthreshold psychotic symptoms (p < 0.005, Cohen’s d = 1.48) and lower thalamic NAA/Cr (p < 0.01, d = 1.17) compared to non-users. There were no differences in medial temporal cortex or anterior cingulate NAA/Cr or in Glu/Cr or Glu + Gln/Cr in any brain region between the two groups. In chronic ketamine users, CAARMS severity of abnormal perceptions was directly correlated with anterior cingulate Glu/Cr (p < 0.05, r = 0.61—uncorrected), but NAA/Cr was not related to any measures of psychopathology.
Conclusions:
The finding of lower thalamic NAA/Cr in chronic ketamine users may be secondary to the effects of ketamine use compared to other drugs of abuse and resembles previous reports in individuals at genetic or clinical risk of schizophrenia
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