Atomtronics with a spin: statistics of spin transport and non-equilibrium orthogonality catastrophe in cold quantum gases

We propose to investigate the full counting statistics of nonequilibrium spin transport with an ultracold atomic quantum gas. The setup makes use of the spin control available in atomic systems to generate spin transport induced by an impurity atom immersed in a spin-imbalanced two-component Fermi gas. In contrast to solid-state realizations, in ultracold atoms spin relaxation and the decoherence from external sources is largely suppressed. As a consequence, once the spin current is turned off by manipulating the internal spin degrees of freedom of the Fermi system, the nonequilibrium spin population remains constant. Thus one can directly count the number of spins in each reservoir to investigate the full counting statistics of spin flips, which is notoriously challenging in solid state devices. Moreover, using Ramsey interferometry, the dynamical impurity response can be measured. Since the impurity interacts with a many-body environment that is out of equilibrium, our setup provides a way to realize the non-equilibrium orthogonality catastrophe. Here, even for spin reservoirs initially prepared in a zero-temperature state, the Ramsey response exhibits an exponential decay, which is in contrast to the conventional power-law decay of Anderson's orthogonality catastrophe. By mapping our system to a multi-step Fermi sea, we are able to derive analytical expressions for the impurity response at late times. This allows us to reveal an intimate connection of the decay rate of the Ramsey contrast and the full counting statistics of spin flips.Comment: 9+11 pages, 10 figure

Cy3 and Cy5 dyes attached to oligonucleotide terminus stabilize DNA duplexes: Predictive thermodynamic model

AbstractCyanine dyes are important chemical modifications of oligonucleotides exhibiting intensive and stable fluorescence at visible light wavelengths. When Cy3 or Cy5 dye is attached to 5′ end of a DNA duplex, the dye stacks on the terminal base pair and stabilizes the duplex. Using optical melting experiments, we have determined thermodynamic parameters that can predict the effects of the dyes on duplex stability quantitatively (ΔG°, Tm). Both Cy dyes enhance duplex formation by 1.2kcal/mol on average, however, this Gibbs energy contribution is sequence-dependent. If the Cy5 is attached to a pyrimidine nucleotide of pyrimidine–purine base pair, the stabilization is larger compared to the attachment to a purine nucleotide. This is likely due to increased stacking interactions of the dye to the purine of the complementary strand. Dangling (unpaired) nucleotides at duplex terminus are also known to enhance duplex stability. Stabilization originated from the Cy dyes is significantly larger than the stabilization due to the presence of dangling nucleotides. If both the dangling base and Cy3 are present, their thermodynamic contributions are approximately additive. New thermodynamic parameters improve predictions of duplex folding, which will help design oligonucleotide sequences for biophysical, biological, engineering, and nanotechnology applications

What is the irrigation potential for Africa?

Although irrigation in Africa has the potential to boost agricultural productivities by at least 50 percent, food production on the continent is almost entirely rainfed. The area equipped for irrigation, currently slightly more than 13 million hectares, makes up just 6 percent of the total cultivated area. Eighty-five percent of Africa’s poor live in rural areas and mostly depend on agriculture for their livelihoods. As a result, agricultural development is key to ending poverty on the continent. Many development organizations have recently proposed to significantly increase investments in irrigation in the region. However, the potential for irrigation investments in Africa is highly dependent upon geographic, hydrologic, agronomic, and economic factors that need to be taken into account when assessing the long-term viability and sustainability of planned projects. This paper analyzes large, dam-based and small-scale irrigation investment needs in Africa based on agronomic, hydrologic, and economic factors. This type of analysis can guide country- and local-level assessment of irrigation potential, which will be important to agricultural and economic development in Africa.internal rate of return, Investment, irrigation potential, large-scale irrigation, small-scale irrigation,

Design of LNA probes that improve mismatch discrimination

Locked nucleic acids (LNA) show remarkable affinity and specificity against native DNA targets. Effects of LNA modifications on mismatch discrimination were studied as a function of sequence context and identity of the mismatch using ultraviolet (UV) melting experiments. A triplet of LNA residues centered on the mismatch was generally found to have the largest discriminatory power. An exception was observed for G–T mismatches, where discrimination decreased when the guanine nucleotide at the mismatch site or even the flanking nucleotides were modified. Fluorescence experiments using 2-aminopurine suggest that LNA modifications enhance base stacking of perfectly matched base pairs and decrease stabilizing stacking interactions of mismatched base pairs. LNAs do not change the amount of counterions (Na(+)) that are released when duplexes denature. New guidelines are suggested for design of LNA probes, which significantly improve mismatch discrimination in comparison with unmodified DNA probes

RePaint-NeRF: NeRF Editting via Semantic Masks and Diffusion Models

The emergence of Neural Radiance Fields (NeRF) has promoted the development of synthesized high-fidelity views of the intricate real world. However, it is still a very demanding task to repaint the content in NeRF. In this paper, we propose a novel framework that can take RGB images as input and alter the 3D content in neural scenes. Our work leverages existing diffusion models to guide changes in the designated 3D content. Specifically, we semantically select the target object and a pre-trained diffusion model will guide the NeRF model to generate new 3D objects, which can improve the editability, diversity, and application range of NeRF. Experiment results show that our algorithm is effective for editing 3D objects in NeRF under different text prompts, including editing appearance, shape, and more. We validate our method on both real-world datasets and synthetic-world datasets for these editing tasks. Please visit https://repaintnerf.github.io for a better view of our results.Comment: IJCAI 2023 Accepted (Main Track

Giant intradural cervical spine arteriovenous malformations – A case and review of literature

•Spinal arteriovenous malformations (SAVM) are very rare.•Therapeutic options can be very challenging since none of them provided a definitive cure to this lesion in literature.•Spinal angiography is the gold standard for all-inclusive assessment of SAVMs.•We believe that incorporation intraoperative angiography during surgery in a hybrid theatre can help achieve a better cure

Dual-Parameter Opto-Mechanical Fiber Optic Sensors for Harsh Environment Sensing: Design, Packaging, Calibration, and Applications

This thesis concerns with the development of a dual-parameter sensor based on fiber Bragg grating (FBG) and a packaging design for high pressure sensing in harsh environment. This thesis starts by introducing a novel design of a partially coated FBG, using a metallic insert and a thermal curing epoxy. An analytical opto-mechanical model, based on couple mode theory, was developed and presented. The experimental and modelling result of the optical response of the partially coated FBG were compared and shown to be in excellent agreement. The experiments were executed on a custom-built fiber optic calibration station. The coated FBG sensor has a temperature sensitivity of 26.9 ± 0.3 pm/°C, which is 2.7 times higher than a bare fiber; and a force sensitivity of 0.104 nm/N, which is 13 times smaller than a bare fiber. The zero reference of the sensor has a drift of a maximum of 70 pm but the sensor is shown to settle within ±5 pm after 3 thermal cycles and 10 tensile loading cycles. A low profile packaging design is presented for a maximum pressure of 20.68 MPa (3000 psi) for harsh environment applications. A detailed study with FEM analysis revealed the optimal design for the package’s sleeve thickness is 0.5 mm. The temperature sensitivity is in close agreement with the unpackaged coated sensor with 10% difference. Compared to the modelling, the equivalent force sensitivity is 27% lower due to prototype dimensional uncertainties and modelling uncertainties with the material properties. The lack of pre-tension of the FBG sensor in the package also attributed to lower force sensitivity at pressure level lower than 4.13 MPa (600 psi).1 yea

Chemical modification at and within nanopowders: Synthesis of core‐shell Al2O3@TiON nanopowders via nitriding nano‐(TiO2)0.43(Al2O3)0.57 powders in NH3

Here, we demonstrate the potential utility of using chemical modification to reorganize metastable nanoparticles into nanostructured nanoparticles without coincidentally inducing extensive necking/sintering. The motivation for this effort derives from the concept that chemical reduction in a single component in a mixed‐metal nanoparticle will create segregated islands of a second immiscible phase. Given the very high chemical energies inherent in nanoparticles, the formation of even smaller islands of a second phase can be anticipated to lead to extremely high interfacial energies that may drive these islands to diffuse to cores or surfaces to form core‐shell structures that minimize such interfacial energies. Thus, ammonolysis of (TiO2)0.43(Al2O3)0.57 composition nanopowders where both elements are approximately uniformly mixed at atomic length scales, under selected conditions (1000°C) for various periods of time at constant NH3 flow rates leads primarily to the reduction in the Ti species to form TiN or TiON which then appears to diffuse to the surface of the particles. The final products consist of Al2O3@TiON core‐shell nanopowders that remain mostly unaggregated pointing to a new mechanism for modifying nanopowder chemistries and physical properties.Peer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/142336/1/jace15303_am.pdfhttps://deepblue.lib.umich.edu/bitstream/2027.42/142336/2/jace15303.pd