Dye lasing in optically manipulated liquid aerosols

We report lasing in airborne, rhodamine B-doped glycerol-water droplets with diameters ranging between 7.7 and 11.0 mu m, which were localized using optical tweezers. While being trapped near the focal point of an infrared laser, the droplets were pumped with a Q-switched green laser. Our experiments revealed nonlinear dependence of the intensity of the droplet whispering gallery modes (WGMs) on the pump laser fluence, indicating dye lasing. The average wavelength of the lasing WGMs could be tuned between 600 and 630 nm by changing the droplet size. These results may lead to new ways of probing airborne particles, exploiting the high sensitivity of stimulated emission to small perturbations in the droplet laser cavity and the gain medium

A method for volume stabilization of single, dye-doped water microdroplets with femtoliter resolution

A self-control mechanism that stabilizes the size of Rhodamine B-doped water microdroplets standing on a superhydrophobic surface is demonstrated. The mechanism relies on the interplay between the condensation rate that was kept constant and evaporation rate induced by laser excitation which critically depends on the size of the microdroplets. The radii of individual water microdroplets (>5 um) stayed within a few nanometers during long time periods (up to 455 seconds). By blocking the laser excitation for 500 msec, the stable volume of individual microdroplets was shown to change stepwise.Comment: to appear in the J. Op. Soc. Am.

Indistinguishable Photons from a Single Molecule

We report the results of coincidence counting experiments at the output of a Michelson interferometer using the zero-phonon-line emission of a single molecule at $1.4 K$. Under continuous wave excitation, we observe the absence of coincidence counts as an indication of two-photon interference. This corresponds to the observation of Hong-Ou-Mandel correlations and proves the suitability of the zero-phonon-line emission of single molecules for applications in linear optics quantum computation.Comment: To appear in Phys. Rev. Let

Professional Development Needs of Turkish Teachers in an Era of National Reforms

An emerging consensus in the teacher education literature confirms that supporting educational reforms and improving designs for national programs can be accomplished simply by maximizing the match between teachers’ expressed needs and the content by which those professional development needs are met. This paper presents an interpretation of findings on Turkish teachers’ in-service training needs during an era of massive reform. The findings indicate that teachers do not report a strong need for any professional development program content. Analyses are based on survey data from 1,730 Turkish teachers from 352 primary schools. The results raise the discussion of whether teachers simply do not want to participate or actually do not need to participate in any more training during this era of massive educational reforms. The paper concludes by outlining policy and practice implications arising from the research

PTPN22 gene polymorphism in Takayasu's arteritis

Objective. Takayasu's arteritis (TA) is a chronic, rare granulomatous panarteritis of unknown aetiology involving mainly the aorta and its major branches. In this study, genetic susceptibility to TA has been investigated by screening the functional single nucleotide polymorphism (SNP) of PTPN22 gene encoding the lymphoid-specific protein tyrosine phosphatase. Methods. Totally, 181 patients with TA and 177 healthy controls are genotyped by PCR-RFLP method for the SNP rs2476601 (A/G) of PTPN22 gene. Polymorphic region was amplified by PCR and digested with Xcm I enzyme. Results. Detected frequencies of heterozygous genotype (AG) were 5.1% (9/177) in control group and 3.8% (7/181) in TA group (P = 0.61, odds ratio: 0.75, 95% CI: 0.3, 2.0). No association with angiographic type, vascular involvement or prognosis of TA was observed either. Conclusion. The distribution of PTPN22 polymorphism did not reveal any association with TA in Turkey. © The Author 2008. Published by Oxford University Press on behalf of the British Society for Rheumatology. All rights reserved

Spin-glasses in optical cavity

Recent advances in nanofabrication and optical control have garnered tremendous interest in multi-qubit-cavity systems. Here we analyze a spin-glass version of such a nanostructure, solving analytically for the phase diagrams in both the matter and radiation subsystems in the replica symmetric regime. Interestingly, the resulting phase transitions turn out to be tunable simply by varying the matter-radiation coupling strength

Yükseköğretimde Karma bir Dersin Tasarımında İyi Uygulama İlkeleri

This study examines students’ perceptions of a blended course which uses the Seven Principles for Good Practice in Undergraduate Education. A blended teacher education course was designed with teaching and learning activities to introduce the Seven Principles for Good Practice. The participants included 47 pre-service teachers in an undergraduate teacher education program in Turkey. Data were collected using both qualitative and quantitative methods, including a questionnaire, student interviews, and discussion forum transcripts. The results indicate that the students’ perceptions of the blended course were mostly positive; the students felt that the blended environment was very useful. The participants perceived six of the seven principles to be helpful, including student-faculty contact, cooperation, time on task, diversity of ways to learn, feedback, and active learning. However, the students also thought that the seventh “expectations” principle needed to be improved.Bu çalışmada, üniversite eğitiminde İyi Uygulama için Yedi İlke’den faydalanılarak tasarlanan “karma bir öğrenme ortamı”a yönelik öğrencilerin algılarına bakılmıştır. Lisans düzeyinde bir ders İyi Uygulama İlkeleri yardımıyla yeniden tasarlanmıştır. Çalışmanın örneklemini Türkiye’deki bir öğretmen eğitimi programında okuyan 47 lisans öğrencisi oluşturmaktadır. Nitel ve nicel veriler üç farklı anket, öğrencilerle yapılan görüşmeler ve tartışma listesi çıktıları yoluyla toplanmıştır. Nitel ve nicel sonuçlar, öğrencilerin iyi uygulama ilkelerinden faydalanılarak tasarlanan karma derse karşı algılarının büyük ölçüde olumlu olduğunu göstermiştir. Sonuçlar öğrencilerin yedi temel ilkeden altısını oluşturan “öğrenci-öğretim elemanları arası iletişim”, “işbirliği”, “zamanlama”, “çeşitlilik ve öğrenme yolları”, “anlık geribildirim” ve “aktif öğrenme”nin karma ortamda desteklendiğini düşündüklerini göstermektedir. Yalnızca “beklenti” unsuruna yönelik öğrenci algılarının diğerlerine göre daha az olumlu olduğu ve bu unsurun geliştirilmesi gerektiği görülmektedir