Kütüphanecilik nedir, ne değildir?

Taha Toros Arşivi, Dosya No: 111-Kütüphaneler. Not: Gazetenin "Düşünenlerin Düşünceleri" köşesinde yayımlanmıştır.İstanbul Kalkınma Ajansı (TR10/14/YEN/0033) İstanbul Development Agency (TR10/14/YEN/0033

The Black Hole in the Compact, High-dispersion Galaxy NGC 1271

Located in the Perseus cluster, NGC 1271 is an early-type galaxy with a small effective radius of 2.2 kpc and a large stellar velocity dispersion of 276 km/s for its K-band luminosity of 8.9x10^{10} L_sun. We present a mass measurement for the black hole in this compact, high-dispersion galaxy using observations from the integral field spectrograph NIFS on the Gemini North telescope assisted by laser guide star adaptive optics, large-scale integral field unit observations with PPAK at the Calar Alto Observatory, and Hubble Space Telescope WFC3 imaging observations. We are able to map out the stellar kinematics on small spatial scales, within the black hole sphere of influence, and on large scales that extend out to four times the galaxy's effective radius. We find that the galaxy is rapidly rotating and exhibits a sharp rise in the velocity dispersion. Through the use of orbit-based stellar dynamical models, we determine that the black hole has a mass of (3.0^{+1.0}_{-1.1}) x 10^9 M_sun and the H-band stellar mass-to-light ratio is 1.40^{+0.13}_{-0.11} M_sun/L_sun (1-sigma uncertainties). NGC 1271 occupies the sparsely-populated upper end of the black hole mass distribution, but is very different from the Brightest Cluster Galaxies (BCGs) and giant elliptical galaxies that are expected to host the most massive black holes. Interestingly, the black hole mass is an order of magnitude larger than expectations based on the galaxy's bulge luminosity, but is consistent with the mass predicted using the galaxy's bulge stellar velocity dispersion. More compact, high-dispersion galaxies need to be studied using high spatial resolution observations to securely determine black hole masses, as there could be systematic differences in the black hole scaling relations between these types of galaxies and the BCGs/giant ellipticals, thereby implying different pathways for black hole and galaxy growth.Comment: accepted for publication in Ap

Comparative evaluation of shear bond strength of three flowable compomers on enamel of primary teeth: An in-vitro study

Background: The aim of the present study was to determine Shear bond strength (SBS) of different flowable compomers on the enamel surface of primary teeth. The null hypothesis to be tested was that none of the flowable compomer would differ significantly from the other two with respect to SBS. As a result, the tested materials that have the easiest application on child patient is preferred. Material and Methods: Sixty newly extracted non carious primary molars were selected. The buccal surface was cleaned and polished to obtain a flat enamel surface. The specimens were randomly divided into three groups of 20 teeth each, based on the flowable compomers applied, as follows: group I: Dyract Flow® (Dentsply, Konstanz, Germany); group II: Twinky Star Flow® (Voco, Cuxhaven, Germany); and group III: R&D Series Nova Compomer Flow® (Imicryl, Konya, Turkey). Results: SBS in group II (6.78± 0.45 MPa) were significantly lower than groups I and III (8.30 ± 0.29 and 8.43 ± 0.66 MPa, respectively) (P<.001). No significant difference was found between groups I and III (P<.05). Conclusions: Significant differences existed between the SBS of the groups. Therefore, the null hypothesis was rejected. Flowable compomers can provide adequate SBS with self-etching system at restoration of primary teeth. Thus, successful restorations in pediatric patients can be done in a practical way. © Medicina Oral S.L

Molecular diversification and preliminary evaluations of some satsuma selections’ performance under mediterranean conditions

Satsuma (Citrus unshiu Marc.) has been cultivated for a long time in Turkey, and therefore variations for agronomical traits are likely among cultivated satsumas due to bud mutations. The objectives of this study were to determine variations for some selected agronomical traits and genetic markers among 21 new satsumas derived from selections. Fruit yield, fruit quality and molecular diversification of these clones were determined. The clones of 62 Adana, 4/2 Izmir and 11/1 Izmir indicated the highest yield. The fruits obtained from all clones were heavier than the control (Owari Satsuma). Molecular analysis, as assessed with 9 random amplification of polymorphic DNA (RAPD) and 14 simple sequence repeats (SSR) primers, indicated that satsuma clones showed a narrow genetic base suggesting that the observed morphological polymorphism within the group must be associated with  somatic mutations which were not detected by these molecular markers.Key words: Mandarins, clonal selection, citrus

Constraints on Non-Commutative Physics Scale with Neutrino-Electron Scattering

Neutrino-electron scatterings ($\nu - e$) are purely leptonic processes with robust Standard Model (SM) predictions. Their measurements can therefore provide constraints to physics beyond SM. Non-commutative (NC) field theories modify space-time commutation relations, and allow neutrino electromagnetic couplings at the tree level. Their contribution to neutrino-electron scattering cross-section was derived. Constraints were placed on the NC scale parameter $\Lambda_{NC}$ from $\nu - e$ experiments with reactor and accelerator neutrinos. The most stringent limit of $\Lambda_{NC} > 3.3 TeV$ at 95% confidence level improves over the direct bounds from collider experiments.Comment: 6 pages, 2 figures, 2 tables, V2: minor revisions to match published versio

Digital Transformation in Higher Education: Maturity and Challenges Post COVID-19

Digital transformation in higher education, especially after COVID-19 is inevitable. This research explores digital transformation maturity and challenges post COVID-19. The significance of the study does not only stem from the critical role of higher education in building the workforce and knowledge economy. This study triangulates the findings of multiple research instruments, including survey, interviews, case study, and direct observation. The research findings show a significant variance between the respondents’ perception of digital transformations maturity levels, and the core requirements of digital transformation maturity. The findings also show the lack of holistic vision, digital transformation competency, and data structure and processing as the leading challenges of digital transformation

Early Laparoscopic Cholecystectomy with Continuous Pressurized Irrigation and Dissection in Acute Cholecystitis

Background. The aim of this study was to evaluate the preliminary results of a new dissection technique in acute cholecystitis. Material and Method. One hundred and forty-nine consecutive patients with acute cholecystitis were operated on with continuous pressurized irrigation and dissection technique. The diagnosis of acute cholecystitis was based on clinical, laboratory, and radiological evidences. Age, gender, time from symptom onset to hospital admission, operative risk according to the American Society of Anesthesiologists (ASA) score, white blood cell count, C-reactive protein test levels, positive findings of radiologic evaluation of the patients, operation time, perioperative complications, mortality, and conversion to open surgery were prospectively recorded. Results. Of the 149 patients, 87 (58,4%) were female and 62 (41,6%) were male. The mean age was 46.3±6.7 years. The median time from symptom onset to hospital admission 3.2 days (range, 1–6). There were no major complications such as bile leak, common bile duct injury or bleeding. Subhepatic liquid collection occurred in 3 of the patients which was managed by percutaneous drainage. Conversion to open surgery was required in four (2,69%) patients. There was no mortality in the study group. Conclusion. Laparoscopic cholecystectomy with continuous pressurized irrigation and dissection technique in acute cholecystitis seems to be an effective and reliable procedure with low complication and conversion rates