Liquid-Phase Chemical Sensing Using Lateral Mode Resonant Cantilevers

Liquid-phase operation of resonant cantilevers vibrating in an out-of-plane flexural mode has to date been limited by the considerable fluid damping and the resulting low quality factors (Q factors). To reduce fluid damping in liquids and to improve the detection limit for liquid-phase sensing applications, resonant cantilever transducers vibrating in their in-plane rather than their out-of-plane flexural resonant mode have been fabricated and shown to have Q factors up to 67 in water (up to 4300 in air). In the present work, resonant cantilevers, thermally excited in an in-plane flexural mode, are investigated and applied as sensors for volatile organic compounds in water. The cantilevers are fabricated using a complementary metal oxide semiconductor (CMOS) compatible fabrication process based on bulk micromachining. The devices were coated with chemically sensitive polymers allowing for analyte sorption into the polymer. Poly(isobutylene) (PIB) and poly(ethylene-co-propylene) (EPCO) were investigated as sensitive layers with seven different analytes screened with PIB and 12 analytes tested with EPCO. Analyte concentrations in the range of 1−100 ppm have been measured in the present experiments, and detection limits in the parts per billion concentration range have been estimated for the polymer-coated cantilevers exposed to volatile organics in water. These results demonstrate significantly improved sensing properties in liquids and indicate the potential of cantilever-type mass-sensitive chemical sensors operating in their in-plane rather than out-of-plane flexural modes

Synchronous multi-color laser network with daily sub-femtosecond timing drift

Filming atoms in motion with sub-atomic spatiotemporal resolution is one of the distinguished scientific endeavors of our time. Newly emerging X-ray laser facilities are the most likely candidates to enable such a detailed gazing of atoms due to their angstrom-level radiation wavelength. To provide the necessary temporal resolution, numerous mode-locked lasers must be synchronized with ultra-high precision across kilometer-distances. Here, we demonstrate a metronome synchronizing a network of pulsed-lasers operating at different center wavelengths and different repetition rates over 4.7-km distance. The network achieves a record-low timing drift of 0.6 fs RMS measured with 2-Hz sampling over 40 h. Short-term stability measurements show an out-of-loop timing jitter of only 1.3 fs RMS integrated from 1 Hz to 1 MHz. To validate the network performance, we present a comprehensive noise analysis based on the feedback flow between the setup elements. Our analysis identifies nine uncorrelated noise sources, out of which the slave laser's inherent jitter dominates with 1.26 fs RMS. This suggests that the timing precision of the network is not limited by the synchronization technique, and so could be much further improved by developing lasers with lower inherent noise.Comment: 12 pages, 4 figure

On the arithmetic sums of Cantor sets

Let C_\la and C_\ga be two affine Cantor sets in $\mathbb{R}$ with similarity dimensions d_\la and d_\ga, respectively. We define an analog of the Bandt-Graf condition for self-similar systems and use it to give necessary and sufficient conditions for having \Ha^{d_\la+d_\ga}(C_\la + C_\ga)>0 where C_\la + C_\ga denotes the arithmetic sum of the sets. We use this result to analyze the orthogonal projection properties of sets of the form C_\la \times C_\ga. We prove that for Lebesgue almost all directions $\theta$ for which the projection is not one-to-one, the projection has zero (d_\la + d_\ga)-dimensional Hausdorff measure. We demonstrate the results on the case when C_\la and C_\ga are the middle-(1-2\la) and middle-(1-2\ga) sets

Double-Free-Layer Stochastic Magnetic Tunnel Junctions with Synthetic Antiferromagnets

Stochastic magnetic tunnel junctions (sMTJ) using low-barrier nanomagnets have shown promise as fast, energy-efficient, and scalable building blocks for probabilistic computing. Despite recent experimental and theoretical progress, sMTJs exhibiting the ideal characteristics necessary for probabilistic bits (p-bit) are still lacking. Ideally, the sMTJs should have (a) voltage bias independence preventing read disturbance (b) uniform randomness in the magnetization angle between the free layers, and (c) fast fluctuations without requiring external magnetic fields while being robust to magnetic field perturbations. Here, we propose a new design satisfying all of these requirements, using double-free-layer sMTJs with synthetic antiferromagnets (SAF). We evaluate the proposed sMTJ design with experimentally benchmarked spin-circuit models accounting for transport physics, coupled with the stochastic Landau-Lifshitz-Gilbert equation for magnetization dynamics. We find that the use of low-barrier SAF layers reduces dipolar coupling, achieving uncorrelated fluctuations at zero-magnetic field surviving up to diameters exceeding ($D\approx 100$ nm) if the nanomagnets can be made thin enough ($\approx 1$-$2$ nm). The double-free-layer structure retains bias-independence and the circular nature of the nanomagnets provides near-uniform randomness with fast fluctuations. Combining our full sMTJ model with advanced transistor models, we estimate the energy to generate a random bit as $\approx$ 3.6 fJ, with fluctuation rates of $\approx$ 3.3 GHz per p-bit. Our results will guide the experimental development of superior stochastic magnetic tunnel junctions for large-scale and energy-efficient probabilistic computation for problems relevant to machine learning and artificial intelligence

Tecrübe Düzeyi ve İşgören Memnuniyeti İlişkisi: Erzurum ve Gaziantep Otel Çalışanları Üzerine Bir Araştırma

Bu araştırma kapsamında içsel bir değer olan tecrübeyi oluşturan unsurların, işgören memnuniyetini oluşturan çok değişkenli yapısı üzerindeki rolü irdelenmiştir. Bu amaç, örneklemin sektör tecrübesi, yaş ve eğitim düzeyi gibi değişkenler doğrultusunda kategorize edilmesini gerektirmektedir. İlgili amaç ayrıca, iş doyumu değişkeni ile söz konusu değişkenlerin kıyas edilmesini gerektirmektedir. İlgili kapsam doğrultusunda, Erzurum ve Gaziantep illerindeki konaklama işletmelerinde, hâlihazırda istihdam edilmiş olan 218 işgörene yönelik görüşler, anket formları aracılığıyla elde edilmiştir. Anket formu, iki bölüm ve kırk yedi ifadeden oluşturulmuştur. Anket formunda yer alan iş tatmin ölçeği, E. Spector tarafından geliştirilmiştir. Ölçeğin geçerlilik ve güvenirliği Davras ve Gülmez (2013) tarafından gerçekleştirilmiştir. Araştırma hipotezlerinin test edilmesi için, kategorik değişkenler ve sürekli değişkenlerin birbirleri ile ilişkisinin irdelenmesi gerekmektedir. Bu kapsamda değişkenler arasındaki etkileşimin irdelenebilmesi adına nicel analiz araçlarından yararlanılmıştır. Araştırma sonucunda, sektör tecrübe düzeyinin işgören mutluluğunu oluşturan terfi ve ücret alt değişkenlerini pozitif yönde etkilediği görülmüştür. Diğer taraftan, yüksek yaş grubundaki işgörenlerin, diğer gruplara göre terfi ve ödül alt değişkenleri açısından daha düşük iş doyumuna sahip olduğu görülmüştür. Eğitim düzeyinde ise iş arkadaşları alt değişkeni bakımından, düşük eğitim düzeyinin işgören memnuniyetini arttırıcı bir etkiye sahip olduğu görülmüştür. Araştırma bulguları geniş ölçekte irdelendiğinde, 38 yaşın kritik bir nokta olarak ön plana çıktığı tespit edilmiştir. Zira, 38 yaş itibariyle katılımcıların iş doyum düzeylerinin arttığı görülmüştür. Bununla birlikte, ilkokul düzeyinde eğitim almış olan katılımcıların diğer eğitim düzeyindeki katılımcılara göre daha yüksek düzeyde iş doyumuna sahip olduğu tespit edilmiştir. Ayrıca, lisans düzeyinde eğitim seviyesi, işgören beklentisini yükselten bir eşik olarak tespit edilmiştir. Son olarak, sektördeki tecrübe düzeyinin, iş doyumunun iktisadi yönünü arttırdığı görülmüştür. Araştırma sonucunda, teorik ve pratik odaklı öneriler geliştirilmiştir

Distribution of selenium in the plume of the Gediz River, Izmir Bay, Aegean Sea

Selenium (Se) variations in the water column, suspended particulate matter, and sediment through the salinity gradient, together with water-quality parameters, were investigated over four different river conditions: lowest–highest runoff and high–low production period between November 2004 and August 2005 in the plume of the Gediz River, Aegean Sea, Turkey. The drainage basin of the Gediz delta is predominantly agricultural and industrial in character. Dissolved Se exceeded the water-quality standard of 5 μg L–1 during high flow and varied from 9.4 μg L–1 to 0.02 μg L–1 through the salinity gradient during the study period. Particulate Se ranged from 5.2 μg L–1 to 0.02 μg L–1. Sediment in the river mouth was highly affected by Se contamination and reached a level greater than four times (7.6 μg L–1 dry wt) the background level. The results indicated that Se supplied by the river was removed rapidly from the water column before the salinity reached an average value of about 20 and accumulated within the delta

Determination of Flower Characteristics of Some Kiwifruit Genotypes (Actinidia Spp.) Obtained with Breeding Program

All Actinidia species are dioecious, male and female flowers grow on separate kiwifruit plants. In breeding studies, it is generally desirable to obtain female individuals. However, male plants are also of great importance for pollination. Therefore, it is necessary to examine the flower characteristics of the genotypes obtained by breeding studies. This research was conducted in the kiwifruit breeding plot of Yalova Atatürk Horticultural Central Research Institute for two years. Genotypes obtained from cultivars belonging to Actinidia deliciosa and Actinidia chinensis were used in the research. At the time of flowering, phenological observations of male and female genotypes, which are prominent in the population, have been made and the developmental stages of the flowers have been determined. At least 10 flowers of each genotype were used to determine the morphological characteristics.Number of leaves, number of petals, number of male organs, number of filaments, number of female organs, number of female organs and number of stylus were examined in order to determine flower characteristics. When the data obtained as a result of two years are evaluated; significant differences have been obtained particularly in terms of flowering time, flowering period, the number of stylus, the filament size, the number of female organs and the number of male organs. Female cultivars/genotypes tend to flowering later than male cultivars/genotypes, and female cultivars/genotypes have shorter filament length than male cultivars/genotypes. It has also been clearly observed that ovaries are not functional in male types

Primary testicular lymphoma: a single centre experience

Aim: Primary testicular lymphoma (PTL) is an uncommon and aggressive form of extranodal non-Hodgkin’s lymphoma (NHL). We aimed to analyse the clinicopathological characteristics and outcomes of our PTL cases. Materials and Methods: A review was made of the medical records of 339 NHL patients who were treated in the Medical Oncology Department between January 2005 and December 2013. Results: 8 PTL patients were identified from the 339 NHL patients. The average age of the patients was 67.7 ± 7.9 years (range 53–79 years). The mean follow-up time was 24.8 months (range 7–98 months). Inguinal orchiectomy was performed as a diagnostic and initial therapy and all the patients underwent 4–6 cycles of chemoimmunotherapy consisting of cyclophosphamide, doxorubicin, vincristine and prednisone plus rituximab. 4 of 8 patients received intrathecal prophylactic chemotherapy and 6 of 8 patients continued contralateral testis irradiation. Relapse occured in only 1 patient in central nervous system after 6 months who had not received intrathecal prophylaxis. No contralateral testis relapse was observed. Conclusions: Primary testicular NHL is an uncommon entity and we evaluated 8 patients; with one relapse in central nervous system and no relapse in the contralateral testis. Key Words: primary testicular lymphoma, contralateral scrotal irradiation, intratechal chemotherapy