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

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 Effect of Climate on the Radial Growth of Scots Pine (Pinus Sylvestris L.) in A Coastal Mixed Stand in Kapisuyu, Bartin, Turkey

Scots pine is geographically the most widespread pine species in the world, and it shows different growth responses to climate and environmental factors in diverse ecological sites. We studied both the stand dynamics and climate-growth relationships of Scots pine in isolated coastal stand (recently found) in the Western Black Sea Region of Turkey. The homogeneity index of this stand has varied between 1.92-3.56. In growth-ring analyses, after cross-dating of individual chronologies, COFECHA and ARSTAN software were used respectively for chronology quality control and standardization (detrend). In this way, a 58-year-long chronology (1959-2016) of Scots pine was constructed. In addition, DENDROCLIM software was used for investigating Scots pine's radial growth-climate relationships. Mean sensitivity changed from 0.163 to 0.331, with a mean of 0.183. Mean correlation among trees and signal to noise ratio were 0.389 and 7.012 respectively. In terms of the effect of precipitation on the radial growth of Scots pine in this site, the correlation coefficients were 0.43 (p<0.05) for December of the previous year and 0.41 (p<0.05) for July of the current year. For all the other months, precipitation had a non-significant effect. As for the maximum and mean air temperature, the correlation coefficients were 0.36 (p<0.05) and 0.40 (p<0.05) for February, and 0.40 (p<0.05) and 0.42 (p<0.05) for March, respectively. However, on the radial growth, while the maximum temperature in August had a negative effect (r= -0.26; p<0.05), minimum temperatures in February, March and July had a positive effect (r= 0.39, 0.40 and 0.34 respectively; p<0.05). It means while higher rains in July and higher temperatures in the late winter-early spring have caused the wider growth rings, the narrower growth rings have been formed in the years with higher maximum temperatures in August in the isolated coastal site of Scots pine

Metaphoric Perceptions of the Preservice Turkish Teachers about the Term 'Philosophy

Felsefe, insanın bilinçlenmesinde, evreni, dünyayı ve kendisini anlama ve anlamlandırmasında önemli bir işleve sahiptir. Öğretmenlik mesleğinin felsefeyle ilişkili olması, Türkçe öğretmenlerinin de dil kullanımı ilkelerini öğreten ve bu vesileyle düşünmeye sevk eden bir alanda olmalarıyla felsefe kavramsal olarak daha da önem kazanmıştır. Bu çalışmanın temel amacı Türkçe eğitimi ana bilim dalı öğrencilerinin "felsefe" kavramına ilişkin algılarını metaforlar aracılığıyla tespit etmektir. Çalışma grubunu Çukurova Üniversitesi Türkçe Eğitimi Ana Bilim Dalında 2, 3 ve 4. sınıflarda eğitim gören öğrencileri oluşturmaktadır. Veri toplama aracı olarak her öğrenciye "Felsefe ... gibidir. Çünkü ..." ifadesinin yazılı olduğu pusulalar verilmiş ve boşlukların doldurulması istenmiştir. Araştırmada elde edilen metaforlar farklı kategorilerde toplanmıştır. Araştırmada felsefenin Türkçe eğitiminde okuyan öğrenciler gözünde nerede olduğu ve eğitimde ne şekilde kullanılacağı hususunda ipuçları elde edilmeye çalışılmıştır.Philosophy has a significant function in the awakening of human, understanding and perceiving the universe, the world and himself. Philosophy has gained more importance conceptually. The basic purpose of this study is to determine the perceptions of the students in the Department of Turkish Education about the term, philosophy through metaphors. The study group consists of the students in the 2nd, 3rd and 4th grades in the Department of Turkish Education in Çukurova University. As data collecting tool, each student was given papers in which the expression -Philosophy is like ..., because ...- is included and they were required to fill in the blank places. The metaphors obtained in the study were collected under different categories. In the study, it was attempted to determine what place the philosophy is in the eyes of the students studying Turkish and find out some clues about how it can be used in education

An Investigation on the Mass Attenuation Coefficients of W-VC-C and W-VC-TiC-C Composites for Gamma Radioisotopes

In this study, tungsten-vanadium carbide-graphite and tungsten-vanadium carbide-titanium carbide-graphite composites (W-VC-TiC-C) which can be used in high-tech equipment were investigated against different gamma radioisotopes. The composite materials were produced via mechanical alloying method in two groups; one of them includes 93% tungsten (W), 6% vanadium carbide (VC) and 1% graphite (C) which was synthesized during three different alloying times (6, 12, 24 hours). Other group of the samples were composited as 91% tungsten, 6% vanadium carbide (VC), 2% titanium carbide (TiC) and 1% graphite (C) which has also three different alloying times (6, 12, 24 hours). Gamma transmission technique was used in the experiments to investigate the gamma attenuation properties of the composite materials. Linear and mass attenuation coefficients of the samples were determined in the experiments and theoretical mass attenuation coefficients were calculated using widely acknowledged XCOM computer code. The experimental mass attenuation coefficients and calculated theoretical results were compared and evaluated with each other. Results showed that gamma attenuation coefficients of the composite materials dependent on alloying time. It can be concluded that increasing the tungsten ratio causes higher linear attenuation coefficient which decreases with increasing gamma energies

The value of plasma SCUBE1 and oxidative stress parameters in the early diagnosis of acute ovarian torsion

Tokgoz, Vehbi Yavuz/0000-0002-4113-385XWOS: 000472479100009PubMed: 31223027AIM: The purpose of our study was to determine the diagnostic value of plasma SCUBE1, malondialdehyde (MDA), superoxide dismutase (SOD) and total antioxidant status (TAS) investigated on the 4th hour of ovarian torsion, and at the same time to determine the relation between these markers and histopathological damage occurring in the ovary. MATERIALS AND METHODS: Sixteen rats were included, eight in the torsion group and eight in the control group. The right ovaries of the rats in the torsion group were rotated clockwise 720 degrees, after which they were fi xed and attached to the abdominal wall. The abdominal walls of the control group rats were opened for 1 min and then closed. Relaparotomy was performed 4 h after surgery in both groups, blood specimens were collected for biochemical analyses, and the right ovaries were surgically extracted. RESULTS: No statistically signifi cant difference was determined in the control and torsion groups' plasma SCUBE1, SOD and TAS values (p = 0.987, p = 0.33, and p = 0.244, respectively). Torsion group plasma MDA values were signifi cantly higher than those of the control group (p = 0.039). At histopathological evaluation, histological score, apoptotic index and Caspase-3 index values of the torsion group were signifi cantly higher compared to the control group. CONCLUSION: Plasma SCUBE1 is not useful in the early diagnosis of ovarian torsion. Similarly, use of the oxidative stress markers SOD and TAS does not appear useful in early diagnosis, although MDA may be considered for that purpose (Tab. 2, Fig. 3, Ref. 23). Text in PDF www.elis.sk.Scientific Research Committee of Giresun University [100517-125]The study was supported by the Scientific Research Committee of Giresun University (100517-125)

Efficacy of manual and mechanical instrumentation techniques for removal of overextended root canal filling material

© 2017 Nigerian Journal of Clinical Practice.Objective: To compare the efficacy of manual and mechanical instrumentation techniques, including ProTaper Universal retreatment system, Mtwo retreatment system, Reciproc system, and Hedström files, regarding removal of overextended root canal filling material. Materials and Methods: Eighty extracted human mandibular premolar teeth were prepared at the apical foramen level using Revo-S rotary files and subsequently obturated. The root canal filling material was deliberately extruded from the apex. Samples were transferred to glass vials that simulated the periapical area. Eighty samples of overfilled teeth were randomly assigned to four equal groups (n = 20) for removal of the root filling material with ProTaper Universal retreatment files (Group 1), Mtwo retreatment files (Group 2), Reciproc system (Group 3), and hand files (Group 4). Removal of the root canal filling material and additional preparation were performed by individual instruments from each different system up to a #40 size. The external apical surface of the teeth and the surrounding glass vials were checked using a dental operation microscope with ×12.5 magnification. Samples were divided into two groups based on whether removal of the overextended root canal filling material was successful or not. The Fisher's exact test was used to detect any significant difference between the groups (α = 0.05). Results: The success rate for removal of overextended gutta-percha was greater for the Mtwo (30%) and hand files (30%) compared with the ProTaper (20%) and Reciproc (10%). However, no significant statistical differences existed among the experimental groups (P > 0.05). Conclusions: This study demonstrated that all tested systems had similar efficacy in removing overextended root canal filling material