On the spectrum of Farey and Gauss maps

In this paper we introduce Hilbert spaces of holomorphic functions given by generalized Borel and Laplace transforms which are left invariant by the transfer operators of the Farey map and its induced version, the Gauss map, respectively. By means of a suitable operator-valued power series we are able to study simultaneously the spectrum of both these operators along with the analytic properties of the associated dynamical zeta functions.Comment: 23 page

The Benefits and Harms of Transmitting Into Space

Deliberate and unintentional radio transmissions from Earth propagate into space. These transmissions could be detected by extraterrestrial watchers over interstellar distances. Here, we analyze the harms and benefits of deliberate and unintentional transmissions relevant to Earth and humanity. Comparing the magnitude of deliberate radio broadcasts intended for messaging to extraterrestrial intelligence (METI) with the background radio spectrum of Earth, we find that METI attempts to date have much lower detectability than emissions from current radio communication technologies on Earth. METI broadcasts are usually transient and several orders of magnitude less powerful than other terrestrial sources such as astronomical and military radars, which provide the strongest detectable signals. The benefits of radio communication on Earth likely outweigh the potential harms of detection by extraterrestrial watchers; however, the uncertainty regarding the outcome of contact with extraterrestrial beings creates difficulty in assessing whether or not to engage in long-term and large-scale METI.Comment: Published in Space Polic

Immediate three-dimensional changes in the oropharynx after different mandibular advancements in counterclockwise rotation orthognathic planning

A retrospective cohort study was performed to evaluate the immediate effect on the oropharynx dimensions from different mandibular advancements in patients undergone counterclockwise rotation (CCW) of the maxillomandibular complex. 138 CBCT images of p

Methylphenidate improves response inhibition but not reflection–impulsivity in children with attention deficit hyperactivity disorder (ADHD)

Impulsivity is a cardinal feature of attention deficit hyperactivity disorder (ADHD), which is thought to underlie many of the cognitive and behavioural symptoms associated with the disorder. Impairments on some measures of impulsivity have been shown to be responsive to pharmacotherapy. However, impulsivity is a multi-factorial construct and the degree to which different forms of impulsivity contribute to impairments in ADHD or respond to pharmacological treatments remains unclear.The aims of the study were to assess the effects of methylphenidate (MPH) on the performance of children with ADHD on measures of reflection-impulsivity and response inhibition and to compare with the performance of healthy volunteers.Twenty-one boys (aged 7-13 years) diagnosed with ADHD underwent a double-blind, placebo-controlled trial of MPH (0.5 mg/kg) during which they performed the Information Sampling Task (IST) and the Stop Signal Task. A healthy age- and education-matched control group was tested on the same measures without medication.Children with ADHD were impaired on measures of response inhibition, but did not demonstrate reflection-impulsivity on the IST. However, despite sampling a similar amount of information as their peers, the ADHD group made more poor decisions. MPH improved performance on measures of response inhibition and variability of response, but did not affect measures of reflection-impulsivity or quality of decision-making.MPH differentially affected two forms of impulsivity in children with ADHD and failed to ameliorate their poor decision-making on the information sampling test.</p

Approach to IAEA material-balance verification at the Portsmouth Gas Centrifuge Enrichment Plant

This paper describes a potential approach by which the International Atomic Energy Agency (IAEA) might verify the nuclear-material balance at the Portsmouth Gas Centrifuge Enrichment Plant (GCEP). The strategy makes use of the attributes and variables measurement verification approach, whereby the IAEA would perform independent measurements on a randomly selected subset of the items comprising the U-235 flows and inventories at the plant. In addition, the MUF-D statistic is used as the test statistic for the detection of diversion. The paper includes descriptions of the potential verification activities, as well as calculations of: (1) attributes and variables sample sizes for the various strata, (2) standard deviations of the relevant test statistics, and (3) the detection sensitivity which the IAEA might achieve by this verification strategy at GCEP

Metformin Activates an Atypical PKC-CBP Pathway to Promote Neurogenesis and Enhance Spatial Memory Formation

SummaryAlthough endogenous recruitment of adult neural stem cells has been proposed as a therapeutic strategy, clinical approaches for achieving this are lacking. Here, we show that metformin, a widely used drug, promotes neurogenesis and enhances spatial memory formation. Specifically, we show that an atypical PKC-CBP pathway is essential for the normal genesis of neurons from neural precursors and that metformin activates this pathway to promote rodent and human neurogenesis in culture. Metformin also enhances neurogenesis in the adult mouse brain in a CBP-dependent fashion, and in so doing enhances spatial reversal learning in the water maze. Thus, metformin, by activating an aPKC-CBP pathway, recruits neural stem cells and enhances neural function, thereby providing a candidate pharmacological approach for nervous system therapy.Video Abstrac

Thalamic pathology and memory loss in early Alzheimer’s disease: moving the focus from the medial temporal lobe to Papez circuit

It is widely assumed that incipient protein pathology in the medial temporal lobe instigates the loss of episodic memory in Alzheimer’s disease, one of the earliest cognitive deficits in this type of dementia. Within this region, the hippocampus is seen as the most vital for episodic memory. Consequently, research into the causes of memory loss in Alzheimer’s disease continues to centre on hippocampal dysfunction and how disease-modifying therapies in this region can potentially alleviate memory symptomology. The present review questions this entrenched notion by bringing together findings from post-mortem studies, non-invasive imaging (including studies of presymptomatic, at-risk cases) and genetically modified animal models. The combined evidence indicates that the loss of episodic memory in early Alzheimer’s disease reflects much wider neurodegeneration in an extended mnemonic system (Papez circuit), which critically involves the limbic thalamus. Within this system, the anterior thalamic nuclei are prominent, both for their vital contributions to episodic memory and for how these same nuclei appear vulnerable in prodromal Alzheimer’s disease. As thalamic abnormalities occur in some of the earliest stages of the disease, the idea that such changes are merely secondary to medial temporal lobe dysfunctions is challenged. This alternate view is further strengthened by the interdependent relationship between the anterior thalamic nuclei and retrosplenial cortex, given how dysfunctions in the latter cortical area provide some of the earliest in vivo imaging evidence of prodromal Alzheimer’s disease. Appreciating the importance of the anterior thalamic nuclei for memory and attention provides a more balanced understanding of Alzheimer’s disease. Furthermore, this refocus on the limbic thalamus, as well as the rest of Papez circuit, would have significant implications for the diagnostics, modelling, and experimental treatment of cognitive symptoms in Alzheimer’s disease