Force-gradient-induced mechanical dissipation of quartz tuning fork force sensors used in atomic force microscopy

We have studied the dynamics of quartz tuning fork resonators used in atomic force microscopy taking into account mechanical energy dissipation through the attachment of the tuning fork base. We find that the tuning fork resonator quality factor changes even for the case of a purely elastic sensor-sample interaction. This is due to the effective mechanical imbalance of the tuning fork prongs induced by the sensor-sample force gradient which in turn has an impact on the dissipation through the attachment of the resonator base. This effect may yield a measured dissipation signal that can be different to the one exclusively related to the dissipation between the sensor and the sample. We also find that there is a second order term in addition to the linear relationship between the sensor-sample force gradient and the resonance frequency shift of the tuning fork that is significant even for force gradients usually present in atomic force microscopy which are in the range of tens of N/m.Comment: 9 pages, 3 figures and supplemental informatio

Commercialization of agriculture in the Himalayas

Increased market integration and commercialization of traditional agriculture in the Himalayas is part of a development strategy towards growth and better standard of living. More than 97 percent households depend upon agricultural and allied activities for livelihood which constitutes 30 percent of the household income. Given the importance of commercialization of agriculture to improve the productivity, per capita income and thereby the standard of living in the Himalayas, we examine the factors affecting the commercialization of agriculture on the basis of primary survey data. The results reveal that the land size, gender of the household head, livestock assets, ethnicity, education and location are important determinants of commercialization. Although commercialization of agriculture is considered as stimulated private-sector activity, public policy is essential to facilitate driving forces viz., trade and market reforms, rural infrastructure, and the institutional framework for legal and contractual arrangements between farmers and processors.Agriculture, Agricultural policy, Rural societies, Market, Household, India, Himalaya, Commercialization, Rural, Poverty, Production

Performance of financial institutions in Bhutan

The Kingdom of Bhutan is a small landlocked country in South Asia, located in the eastern Himalayas, and bordered by India and China. Bhutan is a small and fragile economy with a population of about 687,000. Nevertheless, its banking system plays an essential role in the growth and development of the country. This paper analyzes the financial performance, the development and growth of bank and non-bank financial institutions of Bhutan for the period 1999-2008 using both traditional and data envelopment analysis (DEA). The DEA analysis shows that financial institutions in are efficient and Bhutan National Bank has been the most efficient one. Overall, the paper finds that the ROE of the financial institutions in Bhutan are comparable to the international banks.Bhutan, Financial institutions, Performance, Deposit, Net income

Carbon fibre tips for scanning probe microscopy based on quartz tuning fork force sensors

We report the fabrication and the characterization of carbon fibre tips for their use in combined scanning tunnelling and force microscopy based on piezoelectric quartz tuning fork force sensors. We find that the use of carbon fibre tips results in a minimum impact on the dynamics of quartz tuning fork force sensors yielding a high quality factor and consequently a high force gradient sensitivity. This high force sensitivity in combination with high electrical conductivity and oxidation resistance of carbon fibre tips make them very convenient for combined and simultaneous scanning tunnelling microscopy and atomic force microscopy measurements. Interestingly, these tips are quite robust against occasionally occurring tip crashes. An electrochemical fabrication procedure to etch the tips is presented that produces a sub-100 nm apex radius in a reproducible way which can yield high resolution images.Comment: 14 pages, 10 figure

Dynamics of quartz tuning fork force sensors used in scanning probe microscopy

We have performed an experimental characterization of the dynamics of oscillating quartz tuning forks which are being increasingly used in scanning probe microscopy as force sensors. We show that tuning forks can be described as a system of coupled oscillators. Nevertheless, this description requires the knowledge of the elastic coupling constant between the prongs of the tuning fork, which has not yet been measured. Therefore tuning forks have been usually described within the single oscillator or the weakly coupled oscillators approximation that neglects the coupling between the prongs. We propose three different procedures to measure the elastic coupling constant: an opto-mechanical method, a variation of the Cleveland method and a thermal noise based method. We find that the coupling between the quartz tuning fork prongs has a strong influence on the dynamics and the measured motion is in remarkable agreement with a simple model of coupled harmonic oscillators. The precise determination of the elastic coupling between the prongs of a tuning fork allows to obtain a quantitative relation between the resonance frequency shift and the force gradient acting at the free end of a tuning fork prong.Comment: 16 pages, 6 figures, 2 Table

Finite Size Effects in Separable Recurrent Neural Networks

We perform a systematic analytical study of finite size effects in separable recurrent neural network models with sequential dynamics, away from saturation. We find two types of finite size effects: thermal fluctuations, and disorder-induced `frozen' corrections to the mean-field laws. The finite size effects are described by equations that correspond to a time-dependent Ornstein-Uhlenbeck process. We show how the theory can be used to understand and quantify various finite size phenomena in recurrent neural networks, with and without detailed balance.Comment: 24 pages LaTex, with 4 postscript figures include

In-depth description of Electrohydrodynamic conduction pumping of dielectric liquids: physical model and regime analysis

In this work, we discuss the fundamental aspects of Electrohydrodynamic (EHD) conduction pumping of dielectric liquids. We build a mathematical model of conduction pumping that can be applied to all sizes, down to microsized pumps. In order to do this, we discuss the relevance of the Electrical Double Layer (EDL) that appears naturally on nonmetallic substrates. In the process, we identify a new dimensionless parameter related to the value of the zeta potential of the substrate-liquid pair, which quantifies the influence of these EDLs on the performance of the pump. This parameter also describes the transition from EHD conduction pumping to electro-osmosis. We also discuss in detail the two limiting working regimes in EHD conduction pumping: ohmic and saturation. We introduce a new dimensionless parameter, accounting for the electric field enhanced dissociation that, along with the conduction number, allows us to identify in which regime the pump operates.Ministerio de Ciencia, Innovación y Universidades PGC2018-099217-B-I0

Synchronous genitourinary lichen sclerosus signals a distinct urinary microbiome profile in men with urethral stricture disease.

PurposeAlterations in the urinary microbiome have been associated with urological diseases. The microbiome of patients with urethral stricture disease (USD) remains unknown. Our objective is to examine the microbiome of USD with a focus on inflammatory USD caused by lichen sclerosus (LS).MethodsWe collected mid-stream urine samples from men with LS-USD (cases; n = 22) and non-LS USD (controls; n = 76). DNA extraction, PCR amplification of the V4 hypervariable region of the 16S rRNA gene, and sequencing was done on the samples. Operational taxonomic units (OTUs) were defined using a > 97% sequence similarity threshold. Alpha diversity measurements of diversity, including microbiome richness (number of different OTUs) and evenness (distribution of OTUs) were calculated and compared. Microbiome beta diversity (difference between microbial communities) relationships with cases and controls were also assessed.ResultsFifty specimens (13 cases and 37 controls) produced a 16S rRNA amplicon. Mean sample richness was 25.9 vs. 16.8 (p = 0.076) for LS-USD vs. non-LS USD, respectively. LS-USD had a unique profile of bacteria by taxonomic order including Bacillales, Bacteroidales and Pasteurellales enriched urine. The beta variation of observed bacterial communities was best explained by the richness.ConclusionsMen with LS-USD may have a unique microbiologic richness, specifically inclusive of Bacillales, Bacteroidales and Pasteurellales enriched urine compared to those with non-LS USD. Further work will be required to elucidate the clinical relevance of these variations in the urinary microbiome