Nuclear energy density functional from chiral pion-nucleon dynamics

We calculate the nuclear energy density functional relevant for N=Z even-even nuclei in the systematic framework of chiral perturbation theory. The calculation includes the one-pion exchange Fock diagram and the iterated one-pion exchange Hartree and Fock diagrams. From these few leading order contributions in the small momentum expansion one obtains already a very good equation of state of isospin symmetric nuclear matter. We find that in the region below nuclear matter saturation density the effective nucleon mass $\widetilde M^*(\rho)$ deviates by at most 15% from its free space value $M$, with $0.89M<\widetilde M^*(\rho)<M$ for $\rho < 0.11 {\rm fm}^{-3}$ and $\widetilde M^*(\rho)>M$ for higher densities. The parameterfree strength of the $(\vec\nabla \rho)^2$-term, $F_\nabla(k_f)$, is at saturation density comparable to that of phenomenological Skyrme forces. The magnitude of $F_J(k_f)$ accompanying the squared spin-orbit density $\vec J ^2$ comes out somewhat larger. The strength of the nuclear spin-orbit interaction, $F_{so}(k_f)$, as given by iterated one-pion exchange is about half as large as the corresponding empirical value, however, with the wrong negative sign. The novel density dependencies of $\widetilde M^*(\rho)$ and $F_{\nabla,so,J}(k_f)$ as predicted by our parameterfree calculation should be examined in nuclear structure calculations (after introducing an additional short range spin-orbit contribution constant in density).Comment: 16 pages, 5 figure

The effect of estrogen deficiency and its combination with chronic stress on the condition of periodontal in old rats

The aim of the study was to investigate the effect of ovariectomy and its combination with stress (femoral fracture) on the periodontal condition in old rats. Materials and methods. A total of 24 white female rats were used in the experiment. The first group consisted of intact rats. Rats of the second group were subjected to an ovariectomy (OE) at the age of 2 months. Rats of the third group underwent a fracture of the one femur 1 month before they were euthanized. The animals were sacrificed at 15 months of age. Results. The level of LPO was increased in the liver, salivary glands and alveolar bone process after experimental ovariectomy; the recession defects on molars were significantly increased. Stress (femoral fracture) aggravated the intensification of peroxidation processes in the salivary glands and liver of rats. The levels of nucleic and higher polyene fatty acids in the liver lipids were decreased in the combination of ovariectomy and stress. The level of LPO in the alveolar bone process was not changed significantly. Histomorphometric study of periodontium in rats revealed a decrease in the upper margin of epithelial attachment. Conclusions. Experimental estrogen deficiency caused the most significant pathogenic effect on the periodontium in old rats. The obtained data demonstrate that female sex hormone deficiency is one of the mechanisms in periodontitis pathogenesis

Mid- and Late-Life Diabetes in Relation to the Risk of Dementia: A Population-Based Twin Study

OBJECTIVE—We aimed to verify the association between diabetes and the risk of dementia, Alzheimer's disease, and vascular dementia in twins and to explore whether genetic and early-life environmental factors could contribute to this association

The effect of body mass index on global brain volume in middle-aged adults: a cross sectional study

BACKGROUND: Obesity causes or exacerbates a host of medical conditions, including cardiovascular, pulmonary, and endocrine diseases. Recently obesity in elderly women was associated with greater risk of dementia, white matter ischemic changes, and greater brain atrophy. The purpose of this study was to determine whether body type affects global brain volume, a marker of atrophy, in middle-aged men and women. METHODS: T1-weighted 3D volumetric magnetic resonance imaging was used to assess global brain volume for 114 individuals 40 to 66 years of age (average = 54.2 years; standard deviation = 6.6 years; 43 men and 71 women). Total cerebrospinal fluid and brain volumes were obtained with an automated tissue segmentation algorithm. A regression model was used to determine the effect of age, body mass index (BMI), and other cardiovascular risk factors on brain volume and cognition. RESULTS: Age and BMI were each associated with decreased brain volume. BMI did not predict cognition in this sample; however elevated diastolic blood pressure was associated with poorer episodic learning performance. CONCLUSION: These findings suggest that middle-aged obese adults may already be experiencing differentially greater brain atrophy, and may potentially be at greater risk for future cognitive decline

Networked Learning in 2021: A Community Definition

Introduction (Networked Learning Editorial Collective): Since the turn of this century, much of the world has undergone a tectonic socio-technological change. Computers have left the isolated basements of research institutes and entered people's homes. Network connectivity has advanced from slow and unreliable modems to high-speed broadband. Devices have evolved: from stationary desktop computers to ever-present, always-connected smartphones. These developments have been accompanied by new digital practices, and changing expectations, not least in education, where enthusiasm for digital technologies has been kindled by quite contrasting sets of values. For example, some critical pedagogues working in the traditions of Freire and Illich have understood computers as novel tools for political and social emancipation, while opportunistic managers in cash-strapped universities have seen new opportunities for saving money and/or growing revenues. Irrespective of their ideological leanings, many of the early attempts at marrying technology and education had some features in common: instrumentalist understanding of human relationships with technologies, with a strong emphasis on practice and 'what works'. It is now clear that, in many countries, managerialist approaches have provided the framing, while local constraints and exigencies have shaped operational details, in fields such as e-learning, Technology Enhanced Learning, and others waving the 'Digital' banner. Too many emancipatory educational movements have ignored technology, burying their heads in the sand, or have wished it away, subscribing toa new form of Luddism, even as they sense themselves moving to the margins. But this situation is not set in stone. Our postdigital reality results from a complex interplay between centres and margins. Furthermore, the concepts of centres and margins 'have morphed into formations that we do not yet understand, and they have created (power) relationships which are still unsettled. The concepts … have not disappeared, but they have become somewhat marginal in their own right.' (Jandrić andHayes 2019) Social justice and emancipation are as important as ever, yet they require new theoretical reconfigurations and practices fit for our socio-technological moment. In the 1990s, networked learning (NL) emerged as a critical response to dominant discourses of the day. NL went against the grain in two main ways. First, it embarked on developing nuanced understandings of relationships between humans and technologies; understandings which reach beyond instrumentalism and various forms of determinism. Second, NL embraced the emancipatory agenda of the critical pedagogy movement and has, in various ways, politically committed to social justice (Beaty et al. 2002; Networked Learning Editorial Collective 2020). Gathered around the biennial Networked Learning Conference,1 the Research in NetworkedLearning book series,2 and a series of related projects and activities, the NL community has left a significant trace in educational transformations over the last few decades. Twenty years ago, founding members of the NL community offered a definition of NL which has strongly influenced the NL community’s theoretical perspectives and research approaches (Goodyear et al. 2004).3 Since then, however, the world has radically changed. With this in mind, the Networked Learning Editorial Collective (NLEC) recently published a paper entitled 'Networked Learning: InvitingRedefinition' (2020). In line with NL's critical agenda, a core goal for the paper was to open up a broad discussion about the current meaning and understandings of NL and directions for its further development. The current collectively authored paper presents the responses to the NLEC's open call. With 40 contributors coming from six continents and working across many fields of education, the paper reflects the breadth and depth of current understandings of NL. The responses have been collated, classified into main themes, and lightly edited for clarity. One of the responders, Sarah Hayes, was asked to write aconclusion. The final draft paper has undergone double open review. The reviewers, Laura Czerniewicz and Jeremy Knox, are acknowledged as authors. Our intention, in taking this approach, has been to further stimulate democratic discussion about NL and to prompt some much-needed community-building.lic