Memoryless Algorithms for the Generalized kk-server Problem on Uniform Metrics

We consider the generalized $k$-server problem on uniform metrics. We study the power of memoryless algorithms and show tight bounds of $\Theta(k!)$ on their competitive ratio. In particular we show that the \textit{Harmonic Algorithm} achieves this competitive ratio and provide matching lower bounds. This improves the $\approx 2^{2^k}$ doubly-exponential bound of Chiplunkar and Vishwanathan for the more general setting of uniform metrics with different weights

Parametric Analysis of Horizontal Static and Dynamic Behavior in Different Types of Masonry Structures

This article introduces the "Pre-seismic Survey Form for Masonry" (PRISM), a simplified tool for evaluating masonry structures. It aims to be user-friendly for both experienced surveyors and beginners. The primary objective is to develop PRISM as an efficient means of gathering relevant data that influences the diverse behaviors exhibited by masonry structures, covering both structural and non-structural aspects. PRISM's development involves a parametric method for identifying critical parameters by analyzing drift results from the response spectrum and horizontal static analyses. These analyses are performed on common masonry structures in European Mediterranean nations. The study investigates various factors, including facade openings, materials around openings, wall thickness, ground type, ground acceleration (g), and principal structural material. By examining 300 2D models created in SAP2000, correlations in structural responses are established. The findings of the parametric analysis significantly enrich the qualitative and quantitative comprehension of structural responses. This advancement contributes to the contemporary knowledge of prevalent masonry structures within European Mediterranean regions. The PRISM survey form employs a numeric rating scale format. Notably, PRISM enables surveyors to access field results, minimizing reliance on computers quickly. The form's design also ensures accessibility and data reliability, making it universally applicable while maintaining simplicity. Doi: 10.28991/CEJ-2023-09-10-015 Full Text: PD

Radial peripapillary capillary density as a predictive factor for glaucoma in eyes with ocular hypertension. An observational, comparative, single-centred study [version 1; peer review: 1 approved, 2 approved with reservations]

Background: Ocular hypertension (OH) is a condition characterized by elevated intraocular pressure (IOP) exceeding the normal range, without any evident damage to the optic nerve or visual field defects characteristic of glaucoma. It constitutes a significant precursor to the development of glaucoma, a leading cause of irreversible vision loss worldwide. Emerging evidence has shown that microcirculation alterations in eyes with OH could serve as predicting factors to identify eyes at high risk for progression to glaucoma. In view of the above, the purpose of our study is to investigate microcirculation alterations of the radial peripapillary capillary plexus using optical coherence tomography angiography (OCT-A) in patients with ocular hypertension (OH). Methods: A total of 192 eyes were included in this observational, comparative, single-centre study and were divided in two groups: OH eyes and healthy controls. OCT-A was performed to analyze microcirculation characteristics at the peripapillary area. Radial peripapillary capillary density was measured at the total area of the optic disc and at each separate region (superior, inferior, inside). The parameters of age, medical treatment for ocular hypertension, sex and retinal fiber layer thickness were evaluated.  Results: Total radial peripapillary capillary density was significantly lower in patients with OH than in healthy controls Concerning the microcirculation characteristics at each separate region of the peripapillary area, the results were as follows: inferior radial peripapillary capillary density was significantly decreased in individuals with OH than in controls, while measurements in the superior peripapillary area and internal optic disc were similar in both groups.   Conclusions: Our study indicates decreased radial peripapillary capillary density in eyes with OH. Microcirculation alterations in the inferior peripapillary area could potentially comprise biomarkers for OH progression to glaucoma

Establishment and spread of the invasive ladybird Harmonia axyridis (Coleoptera: Coccinellidae) in Greece: based on contributions from citizen scientists

Harmonia axyridis (Pallas, 1773), also known as the harlequin ladybird, is an invasive non-native species intentionally introduced to many countries as a biological control agent of agricultural pests. In Greece, H. axyridis was first introduced as a biological control agent in 1994, with releases taking place between 1994 and 2000. For many years there was no evidence to indicate that H. axyridis had established self-sustaining populations. In 2008, a citizen science campaign was initiated aimed at raising awareness regarding the invasive status of H. axyridis to farmers and agronomists. The campaign did not yield results, and it was discontinued in 2011. During this study, the distribution, phenology, and presence of H. axyridis in different habitat types and protected areas in Greece are investigated, using both citizen science data and literature records. Records from iΝaturalist, the Alientoma database and social media examined herein demonstrate that H. axyridis has been established in Greece since 2010. Harmonia axyridis is currently present in 13 administrative districts of Greece, most of them at a considerable distance from the initial release sites. The harlequin ladybird is present in urban and agricultural habitats as well as seventeen NATURA 2000 sites. The adverse socioeconomic and environmental impacts of H. axyridis are briefly discussed alongside suggestions for management activities. Based on our findings, we propose the establishment of a national monitoring scheme for H. axyridis and native ladybirds that will also encourage public participation in recording ladybird observations and provide information on the distribution, spread and impact of this invasive non-native species

Plasticity in dendroclimatic response across the distribution range of Aleppo pine (Pinus halepensis)

We investigated the variability of the climate-growth relationship of Aleppo pine across its distribution range in the Mediterranean Basin. We constructed a network of tree-ring index chronologies from 63 sites across the region. Correlation function analysis identified the relationships of tree-ring index to climate factors for each site. We also estimated the dominant climatic gradients of the region using principal component analysis of monthly, seasonal, and annual mean temperature and total precipitation from 1,068 climatic gridpoints. Variation in ring width index was primarily related to precipitation and secondarily to temperature. However, we found that the dendroclimatic relationship depended on the position of the site along the climatic gradient. In the southern part of the distribution range, where temperature was generally higher and precipitation lower than the regional average, reduced growth was also associated with warm and dry conditions. In the northern part, where the average temperature was lower and the precipitation more abundant than the regional average, reduced growth was associated with cool conditions. Thus, our study highlights the substantial plasticity of Aleppo pine in response to different climatic conditions. These results do not resolve the source of response variability as being due to either genetic variation in provenance, to phenotypic plasticity, or a combination of factors. However, as current growth responses to inter-annual climate variability vary spatially across existing climate gradients, future climate-growth relationships will also likely be determined by differential adaptation and/or acclimation responses to spatial climatic variation. The contribution of local adaptation and/or phenotypic plasticity across populations to the persistence of species under global warming could be decisive for prediction of climate change impacts across populations. In this sense, a more complex forest dynamics modeling approach that includes the contribution of genetic variation and phenotypic plasticity can improve the reliability of the ecological inferences derived from the climate-growth relationships.This work was partially supported by Spanish Ministry of Education and Science co-funded by FEDER program (CGL2012-31668), the European Union and the National Ministry of Education and Religion of Greece (EPEAEK- Environment – Archimedes), the Slovenian Research Agency (program P4-0015), and the USDA Forest Service. The cooperation among international partners was supported by the COST Action FP1106, STREeSS

The evolution of free and bound waves during dispersive focusing in a numerical and physical flume

publisher: Elsevier articletitle: The evolution of free and bound waves during dispersive focusing in a numerical and physical flume journaltitle: Coastal Engineering articlelink: http://dx.doi.org/10.1016/j.coastaleng.2017.11.003 content_type: article copyright: © 2017 The Authors. Published by Elsevier B.V

Mitochondrial superclusters influence age of onset of Parkinson’s disease in a gender specific manner in the Cypriot population: A case-control study

Despite evidence supporting an involvement of mitochondrial dysfunction in the pathogenesis of some neurodegenerative disorders, there are inconsistent findings concerning mitochondrial haplogroups and their association to neurodegenerative disorders, including idiopathic Parkinson's disease (PD).To test this hypothesis for the Greek-Cypriot population, a cohort of 230 PD patients and 457 healthy matched controls were recruited. Mitochondrial haplogroup distributions for cases and controls were determined. Association tests were carried out between mitochondrial haplogroups and PD.Mitochondrial haplogroup U was associated with a reduced PD risk in the Cypriot population. After pooling mitochondrial haplogroups together into haplogroup clusters and superclusters, association tests demonstrated a significantly protective effect of mitochondrial haplogroup cluster N (xR) and supercluster LMN for PD risk only in females. In addition, for female PD cases belonging to UKJT and R (xH, xUKJT) haplogroup, the odds of having a later age of onset of PD were 13 and 15 times respectively higher than the odds for female cases with an H haplogroup.Statistically significant associations regarding PD risk and PD age of onset were mostly detected for females thus suggesting that gender is a risk modifier between mitochondrial haplogroups and PD status / PD age of onset. The biological mechanisms behind this gender specificity remain to be determined

Memoryless Algorithms for the Generalized k-server Problem on Uniform Metrics.

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