Simple models for scaling in phylogenetic trees

Many processes and models --in biological, physical, social, and other contexts-- produce trees whose depth scales logarithmically with the number of leaves. Phylogenetic trees, describing the evolutionary relationships between biological species, are examples of trees for which such scaling is not observed. With this motivation, we analyze numerically two branching models leading to non-logarithmic scaling of the depth with the number of leaves. For Ford's alpha model, although a power-law scaling of the depth with tree size was established analytically, our numerical results illustrate that the asymptotic regime is approached only at very large tree sizes. We introduce here a new model, the activity model, showing analytically and numerically that it also displays a power-law scaling of the depth with tree size at a critical parameter value.Comment: 7 pages, 4 figures. A new figure, with example trees, has been added. To appear in Int. J. Bifurcation and Chao

Impacts of eutrophication and deoxygenation on the sediment biogeochemistry in the Sea of Marmara

The biogeochemistry of seafloor sediments can be significantly altered in response to deoxygenation and eutrophication-driven organic carbon production, resulting in increased benthic fluxes of dissolved nutrients (such as ammonia and phosphate) and metals. The Sea of Marmara, which has also faced large-scale mucilage outbreaks in recent years, is undergoing severe eutrophication and deoxygenation, but the consequences on sediment biogeochemistry and benthic feedback have not been studied so far. This study aims to understand the impacts of deoxygenation and coastal eutrophication on sedimentary biogeochemical processes in the Sea of Marmara, which experiences varying degrees of anthropogenic pressure along with natural inputs from the adjacent Black Sea via Bosphorus surface inflows. Multicore-obtained undisturbed sediment core samples indicate that oxic respiration no longer plays a significant role in Marmara sediments, but denitrification, metal reduction, and sulfate respiration are prevalent as respiratory pathways. The deep-water sediments become more reducing in the Eastern Marmara compared to the Western part of the sea. Cores from İzmit Bay, the Easternmost region in Marmara, exhibit permanently sulfidic conditions with anaerobic oxidation of methane (AOM) controlling downcore sulfide profiles. Calculated diffusive benthic nutrient fluxes show markedly high phosphate and ammonium fluxes into the near-bottom waters of highly eutrophic areas of the Eastern Marmara, which are expected to enhance primary production in the upper layer during the dry season. On the other hand, these sediments are a net sink for nitrate due to the denitrification. Benthic nutrient dynamics contribute to the accumulation of organic matter as well as shifting N/P ratios and the development of a steep hypoxic zone at halocline boundary depths. Additionally, we show that sediments are already influenced by widespread hypoxia in the Sea of Marmara and benthic-pelagic coupling has enhanced the existing eutrophication problem, analogous to the benthic “vicious cycle” observed in the shallower Baltic Sea. We conclude that the Sea of Marmara is now on a clear path towards being included within the list of famous “dead zones” of the Earth's oceans, such as the Baltic Sea, the Gulf of Mexico, or Chesapeake Bay. For the marine management efforts and ecosystem modeling studies, hypoxia-induced benthic biogeochemical processes and benthic-pelagic coupled cycling of nutrients in the Sea of Marmara should be considered.</p

Delamination technique together with longitudinal incisions for treatment of Chiari I/syringomyelia complex: a prospective clinical study

<p>Abstract</p> <p>Background</p> <p>Treatment modalities in Chiari malformation type 1(CMI) accompanied by syringomyelia have not yet been standardized. Pathologies such as a small posterior fossa and thickened dura mater have been discussed previously. Various techniques have been explored to enlarge the foramen magnum and to expand the dura. The aim of this clinical study was to explore a new technique of excision of the external dura accompanied by widening the cisterna magna and making longitudinal incisions in the internal dura, without disturbing the arachnoid.</p> <p>Methods</p> <p>Ten patients with CMI and syringomyelia, operated between 2004 and 2006, formed this prospective series. All cases underwent foramen magnum decompression of 3 × 3 cm area with C1–C2 (partial) laminectomy, resection of foramen magnum fibrous band, excision of external dura, delamination and widening of internal dura with longitudinal incisions.</p> <p>Results</p> <p>Patients were aged between 25 and 58 years and occipital headache was the most common complaint. The mean duration of preoperative symptoms was 4 years and the follow-up time was 25 months. Clinical progression was halted for all patients; eight patients completely recovered and two reported no change. In one patient, there was a transient cerebrospinal fluid (CSF) fistula that was treated with tissue adhesive. While syringomyelia persisted radiologically with radiological stability in five patients; for three patients the syringomyelic cavity decreased in size, and for the remaining two it regressed completely.</p> <p>Conclusion</p> <p>Removal of the fibrous band and the outer dural layer, at level of foramen magnum, together with the incision of inner dural layer appears to be good technique in adult CMI patients. The advantages are short operation time, no need for duraplasty, sufficient posterior fossa decompression, absence of CSF fistulas as a result of extra arachnoidal surgery, and short duration of hospitalization. Hence this surgical technique has advantages compared to other techniques.</p

The Sexual Development and Education of Preschool Children: Knowledge and Opinions from Doctors and Nurses

This descriptive study was carried out in order to determine the knowledge levels and attitudes of doctors and nurses regarding children’s sexual development and sex education. The study was conducted with doctors and nurses who work at various clinics of two state hospitals located in the province of Istanbul. The data collection tool consisted of 58 questions. The Statistical Program for the Social Sciences, version 18.0 (SPSS 18.0) was used for data analysis. It was determined that females comprised the majority of the respondents (61 %) and were over 36 years of age (54.1 %) (37.81 ± 8.82). Of the participants in the study, 63.5 % had bachelor’s degrees and 62.1 % were medical doctors. It was determined that the number of correct responses given by the respondents regarding some behaviors observed in children aged between 3 and 6 years and children’s sexual development and sex education showed significant differences according to age group (p = 0.007), marital status (p = 0.004), the status of having children (p = 0.004), educational status (p = 0.005) and occupation (p = 0.000). However, in a review of the study findings, it was observed that culture had an important impact on sex-related approaches and that embarrassment and shyness is very common

The effect of DEBIO 1143 usage alone or in combination with tamoxifen on estrogen receptor positive breast cancer cell lines; [DEBIO 1143’ün tek başına veya tamoxifenle kombinasyonunun östrojen reseptörü pozitif meme kanseri hücre hatlarındaki etkisi]

Purpose: To investigate the effect of increased concentrations of tamoxifen (TAM) and DEBIO 1143 (AT-406) administered alone or in combination on cells in MCF-7 and BT-474 estrogen receptor positive (ER+) breast cancer cell lines. Materials and methods: The effect of tamoxifen and DEBIO 1143 administered alone or in combination on cell viability in MCF-7 and BT-474 cell lines at the 72nd hour was assessed by the XTT test. Multi-parameter apoptosis assay kit was used to display the effect of the alone/combination of TAM and DEBIO 1143 on both cell lines. Fluorescence microscobic analysis was performed. Results: The IC50 value of TAM was 3.8±0.6 micromolar (μΜ) and 18.9±6.7 μΜ in the MCF-7 and BT-474 cell lines, respectively. The IC50 value of DEBIO 1143 was 15±0.5 μM in the MCF-7 cell line. The results related to drug combination were statistically significant for both cell lines (p<0.001). The decrease in cell viability was not associated with apoptosis. Conclusion: In ER+breast cancer cell lines, the combined doses of the TAM and DEBIO 1143 reduced cell viability more than their administration alone. Combined administrations in both cell lines were concluded in a synergistic effect. Further research is needed to determine which cell death type other than apoptosis is associated with a reduction in cell viability caused by combined administration. © 2020, Pamukkale University. All rights reserved

The role of hydroxytyrosol in health and disease; [Sağlık ve hastalıkta hidroksitirozolün rolü]

Hydroxytyrosol is a phenolic compound released from the hydrolysis of oleuropein and is present in olive oil, leaf and fruit. Recently, studies on hydroxytyrosol have revealed its strong antioxidant and antiinflamatory effects. In vitro studies conducted in various cancer cell lines and in vivo assays carried out on animals reported strong evidences for its antiinflamatory, antiproliferative and proapoptotic influences. In addition, in cancer it is believed to have inhibitory effects during angiogenesis. Its modulatory role on bone formation and prevention of bone loss has been the attraction of some studies. If the molecular mechanisms and cellular pathways of hydroxytyrosol are elucidated, it will be possible to plan new strategies targeting various disease involved with cancer, inflammatory and cardio-vascular pathologies. In this review, various in vitro and in vivo studies investigating the antioxidant, anticancer, antiinflamatory role of hydroxytyrosol and its inhibitory effects in osteoporosis are discussed. © 2014 Turkish Society for Radiation Oncology