Leaf-to-leaf distances and their moments in finite and infinite m-ary tree graphs

We study the leaf-to-leaf distances on full and complete m-ary graphs using a recursive approach. In our formulation, leaves are ordered along a line. We find explicit analytical formulae for the sum of all paths for arbitrary leaf-to-leaf distance r as well as the average path lengths and the moments thereof. We show that the resulting explicit expressions can be recast in terms of Hurwitz-Lerch transcendants. Results for periodic trees are also given. For incomplete random binary trees, we provide first results by numerical techniques; we find a rapid drop of leaf-to-leaf distances for large r.Comment: 10 pages, 7 figure

From Open Content Repositories to Open Sensemaking Communities

The Open Content movement is concerned with enabling students and educators to access material, in order to then learn from it, and reuse it either in one’s studies or one’s own courses. The core efforts to date has focused on enabling access, e.g. building the organizational/political will to release and license content, and in developing open infrastructures for educators to then publish and reassemble it. The key challenge in the next phase of the open content movement is to improve the support for prospective students to engage with and learn from the material, and with each other though peer learning support, in the absence of formally imposed study timetables and assessment deadlines. This paper reports on tools for e-learning and collaborative sensemaking developed at the UK Open University which are now being considered as candidates for open content learning support

The Center for Epidemiologic Studies-Depression (CES-D) scale measures a continuum from well-being to depression: Testing two key predictions of positive clinical psychology

Background: Two core but untested predictions of Positive Clinical Psychology (PCP) are that (1) Many psychiatric problems can be understood as one end of bipolar continua with well-being, and (2) that reducing psychiatric symptoms will provide an equal (near linear) decrease in risk for several other psychiatric variables, irrespective of position on continua.  Aims: We test these predictions in relation to a purported well-being/depression continuum, as measured by the Center for Epidemiologic Studies-Depression (CES-D), a popular measure of depressive experiences in research and clinical practice.  Method: A large (N = 4,138), diverse sample completed the CES-D, which contains a mixture of negatively worded and positively worded items (e.g., “I felt sad,” “I enjoyed life”). The latter are conventionally reverse scored to compute a total score. We first examined whether purportedly separate well-being and depression CES-D factors can be reconceptualised as a bipolar well-being/depression continuum. We then characterised the (linear or nonlinear) form of the relationship between this continuum and other psychiatric variables.  Results: Both predictions were supported. When controlling for shared method bias amongst positively worded items, a single factor well-being/depression continuum underlies the CES-D. Baseline levels on this continuum are found to have near linear relationships with changes in anxiety symptoms, aggression, and substance misuse over time, demonstrating that moving from depression to well-being on the CES-D provides an equal decrease in risk for several other psychological problems irrespective of position on the continuum.  Limitations: The CES-D does not measure well-being as comprehensively as established scales of well-being.  Conclusions: Results support calls for mental health services to jointly focus on increasing well-being and reducing distress, and point to the value of early intervention and instilling resilience in order to prevent people moving away from high levels of well-being

Attitudes, Beliefs, and Perceptions on Cannabis Among Older Adults Aged 65 and Older: A cross-sectional Survey.

OBJECTIVE: With the rise of medical and recreational cannabis use among older adults, concerns about the potential risks and benefits of cannabis use are increasing. This pilot study aimed to determine the attitudes, beliefs, and perceptions of older adults toward cannabis as a medicinal product, to establish a foundation for future research on how healthcare providers communicate with this population regarding cannabis. METHODS: A cross-sectional survey was conducted on adults aged 65 and older living in Philadelphia. The survey included questions related to participants\u27 demographics, knowledge, attitudes, beliefs, and perceptions of cannabis. Participants were recruited via flyer distributions, publications in newsletters, and a local newspaper. Surveys were conducted from December 2019 through May 2020. Quantitative data were presented using counts, mean, median, and percentages, and qualitative data were analyzed by categorizing common responses. RESULTS: The study aimed to recruit 50 participants, of whom 47 met the requirements, and had their data analyzed, resulting in an average age of 71 years. The majority of participants were male (53%) and Black (64%). Seventy-six percent of participants considered cannabis a highly important treatment for older adults, and 42% considered themselves highly knowledgeable about cannabis. Over half of the participants reported being asked about tobacco (55%) or alcohol (57%) use by their PCP compared to 23% being asked about cannabis. Participants indicated that they most commonly turned to the internet and social media for information about cannabis, while only a small number mentioned relying on their primary care physician (PCP) for such information. DISCUSSION: The results of this pilot study highlight the need for accurate and reliable information about cannabis for older adults and their healthcare providers. As the use of cannabis as a therapy continues to rise, it is crucial for healthcare providers to address misconceptions and encourage older adults to seek out evidence-based research. Further research is needed to explore healthcare providers\u27 perceptions of cannabis therapy and how they can better educate older adults

Neural coding in the visual system of Drosophila melanogaster: how do small neural populations support visually guided behaviours?

All organisms wishing to survive and reproduce must be able to respond adaptively to a complex, changing world. Yet the computational power available is constrained by biology and evolution, favouring mechanisms that are parsimonious yet robust. Here we investigate the information carried in small populations of visually responsive neurons in Drosophila melanogaster. These so-called ‘ring neurons’, projecting to the ellipsoid body of the central complex, are reported to be necessary for complex visual tasks such as pattern recognition and visual navigation. Recently the receptive fields of these neurons have been mapped, allowing us to investigate how well they can support such behaviours. For instance, in a simulation of classic pattern discrimination experiments, we show that the pattern of output from the ring neurons matches observed fly behaviour. However, performance of the neurons (as with flies) is not perfect and can be easily improved with the addition of extra neurons, suggesting the neurons’ receptive fields are not optimised for recognising abstract shapes, a conclusion which casts doubt on cognitive explanations of fly behaviour in pattern recognition assays. Using artificial neural networks, we then assess how easy it is to decode more general information about stimulus shape from the ring neuron population codes. We show that these neurons are well suited for encoding information about size, position and orientation, which are more relevant behavioural parameters for a fly than abstract pattern properties. This leads us to suggest that in order to understand the properties of neural systems, one must consider how perceptual circuits put information at the service of behaviour

Tunable Surface Properties of Aluminum Oxide Nanoparticles from Highly Hydrophobic to Highly Hydrophilic

The formation of materials with tunable wettability is important for applications ranging from antifouling to waterproofing surfaces. We report the use of various low-cost and nonhazardous hydrocarbon materials to tune the surface properties of aluminum oxide nanoparticles (NPs) from superhydrophilic to superhydrophobic through covalent functionalization. The hydrocarbon surfaces are compared with a fluorinated surface for wettability and surface energy properties. The role of NPs’ hydrophobicity on their dynamic interfacial behavior at the oil–water interface and their ability to form stable emulsions is also explored. The spray-coated NPs provide textured surfaces (regardless of functionality), with water contact angles (θ) of 10–150° based on their surface functionality. The superhydrophobic NPs are able to reduce the interfacial tension of various oil–water interfaces by behaving as surfactants

Frequency Locked Microtoroid Optical Resonators as a Non-Invasive Tumor Biopsy Alternative

Whispering gallery mode optical resonators offer an unusual coupling of rapid response time and ultra-sensitive biological and chemical detection. We have improved the signal to noise ratio of microtoroid optical resonators ∼1000-fold over standard techniques by using laser frequency locking and have applied this to assay tumor progression in mice by sensing the low concentrations of exosomes, shed by tumor cells, in serum samples collected from the animals. Serum samples from normal or experimental mice cause no shift in the resonance wavelength of the microtoroids; however, after using antibodies toward specific tumor markers to sensitize the toroid surface, we detected changes in the resonance frequency of the microtoroid when exposed to the serum of tumor-implanted mice. Serum from control (tumor-free) mice caused no shift. The wavelength shifts observed were 600 times the noise and drift of the sensor, even for a million fold dilution of the serum sample. Analysis of the shifts showed unitary steps of ∼ 0.5 fm, suggesting that the assay may be sensitive enough to detect individual binding events, offering a means to analyze the size of the biomolecules that are binding to the resonator. If validated, this approach offers a non-invasive tumor “biopsy,” exploiting the circulation of blood to collect a sample of tumor surfaces without the need to find or access the tumors