Detection of DNA and Poly-L-Lysine using CVD Graphene-channel FET Biosensors

A graphene channel field-effect biosensor is demonstrated for detecting the binding of double-stranded DNA and poly-l-lysine. Sensors consist of CVD graphene transferred using a clean, etchant-free transfer method. The presence of DNA and poly-l-lysine are detected by the conductance change of the graphene transistor. A readily measured shift in the Dirac Voltage (the voltage at which the graphenes resistance peaks) is observed after the graphene channel is exposed to solutions containing DNA or poly-l-lysine. The Dirac voltage shift is attributed to the binding/unbinding of charged molecules on the graphene surface. The polarity of the response changes to positive direction with poly-l-lysine and negative direction with DNA. This response results in detection limits of 8 pM for 48.5 kbp DNA and 11 pM for poly-l-lysine. The biosensors are easy to fabricate, reusable and are promising as sensors of a wide variety of charged biomolecule

Low-power photothermal self-oscillation of bimetallic nanowires

We investigate the nonlinear mechanics of a bimetallic, optically absorbing SiN-Nb nanowire in the presence of incident laser light and a reflecting Si mirror. Situated in a standing wave of optical intensity and subject to photothermal forces, the nanowire undergoes self-induced oscillations at low incident light thresholds of $<1\, \rm{\mu W}$ due to engineered strong temperature-position ($T$-$z$) coupling. Along with inducing self-oscillation, laser light causes large changes to the mechanical resonant frequency $\omega_0$ and equilibrium position $z_0$ that cannot be neglected. We present experimental results and a theoretical model for the motion under laser illumination. In the model, we solve the governing nonlinear differential equations by perturbative means to show that self-oscillation amplitude is set by the competing effects of direct $T$-$z$ coupling and $2\omega_0$ parametric excitation due to $T$-$\omega_0$ coupling. We then study the linearized equations of motion to show that the optimal thermal time constant $\tau$ for photothermal feedback is $\tau \to \infty$ rather than the widely reported $\omega_0 \tau = 1$. Lastly, we demonstrate photothermal quality factor ($Q$) enhancement of driven motion as a means to counteract air damping. Understanding photothermal effects on micromechanical devices, as well as nonlinear aspects of optics-based motion detection, can enable new device applications as oscillators or other electronic elements with smaller device footprints and less stringent ambient vacuum requirements.Comment: New references adde

Long-Term Dynamic Humoral Response to SARS-CoV-2 mRNA Vaccines in Patients on Peritoneal Dialysis

COVID-19; Booster; Chronic kidney diseaseCOVID-19; Refuerzo; Enfermedad renal crónicaCOVID-19; Reforç; Malaltia renal crònicaIntroduction. Patients on peritoneal dialysis (PD) present an impaired humoral response against SARS-CoV-2, at least after the initial vaccination and booster dose. Until now, the effect of a fourth dose has not been established. The aim of the present study is to evaluate the long-term dynamics of the humoral response of PD patients to multiple doses of SARS-CoV-2 vaccines, focusing on the effect of the fourth dose. Methods. This is an analysis of the prospective and multicentric SENCOVAC study. We included patients on PD without additional immunosuppression that had received at least 3 SARS-CoV-2 mRNA vaccine doses. We evaluated anti-spike antibody titers after the initial vaccination, third and fourth doses, using prespecified fixed assessments (i.e., baseline, 28 days, 3, 6, and 12 months after completing the initial vaccine schedule). Breakthrough infections were also collected. Results. We included 164 patients on PD (69% males, 62 ± 13 years old). In patients who had received only two doses, the rates of positive humoral response progressively decreased from 96% at 28 days to 80% at 6 months, as did with anti-spike antibody titers. At 6 months, 102 (62%) patients had received the third vaccine dose. Patients with the third dose had higher rates of positive humoral response (p = 0.01) and higher anti-spike antibody titers (p < 0.001) at 6 months than those with only 2 doses. At 12 months, the whole cohort had received 3 vaccine doses, and 44 (27%) patients had an additional fourth dose. The fourth dose was not associated to higher rates of positive humoral response (100 vs. 97%, p = 0.466) or to statistically significant differences in anti-spike antibody titers as compared to three doses (p = 0.371) at 12 months. Prior antibody titers were the only predictor for subsequent higher anti-spike antibody titer (B 0.53 [95%CI 0.27–0.78], p < 0.001). The 2 (1.2%) patients that developed COVID-19 during follow-up had mild disease. Conclusions. PD presents an acceptable humoral response with three doses of SARS-CoV-2 vaccines that improve the progressive loss of anti-spike antibody titers following two vaccine doses.The present project has been supported by Diaverum, Vifor Pharma, Vircell, Fundación Renal Iñigo Álvarez de Toledo, and ISCIII FEDER funds RICORS2040 (RD21/0005)

The York map as a Shanmugadhasan canonical transformation in tetrad gravity and the role of non-inertial frames in the geometrical view of the gravitational field

A new parametrization of the 3-metric allows to find explicitly a York map in canonical ADM tetrad gravity, the two pairs of physical tidal degrees of freedom and 14 gauge variables. These gauge quantities (generalized inertial effects) are all configurational except the trace ${}^3K(\tau ,\vec \sigma)$ of the extrinsic curvature of the instantaneous 3-spaces $\Sigma_{\tau}$ (clock synchronization convention) of a non-inertial frame. The Dirac hamiltonian is the sum of the weak ADM energy $E_{ADM} = \int d^3\sigma {\cal E}_{ADM}(\tau ,\vec \sigma)$ (whose density is coordinate-dependent due to the inertial potentials) and of the first-class constraints. Then: i) The explicit form of the Hamilton equations for the two tidal degrees of freedom in an arbitrary gauge: a deterministic evolution can be defined only in a completely fixed gauge, i.e. in a non-inertial frame with its pattern of inertial forces. ii) A general solution of the super-momentum constraints, which shows the existence of a generalized Gribov ambiguity associated to the 3-diffeomorphism gauge group. It influences: a) the explicit form of the weak ADM energy and of the super-momentum constraint; b) the determination of the shift functions and then of the lapse one. iii) The dependence of the Hamilton equations for the two pairs of dynamical gravitational degrees of freedom (the generalized tidal effects) and for the matter, written in a completely fixed 3-orthogonal Schwinger time gauge, upon the gauge variable ${}^3K(\tau ,\vec \sigma)$, determining the convention of clock synchronization. Therefore it should be possible (for instance in the weak field limit but with relativistic motion) to try to check whether in Einstein's theory the {\it dark matter} is a gauge relativistic inertial effect induced by ${}^3K(\tau ,\vec \sigma)$.Comment: 90 page

Abundant bacteria in the proximal and distal intestine of healthy Siberian sturgeons (Acipenser baerii)

The gut microbiota plays a key role in animal health, including immune and metabolic homeostasis. Despite the economic relevance of the sturgeon, studies addressing the gut microbiome of this species are scarce and have focused only on the hindgut. The objective of this work was to use Illumina metabarcoding technology to compare the bacterial microbiomes of two different intestinal locations, the proximal intestine (small intestine) and the distal intestine (hindgut containing the spiral valve), of healthy Siberian sturgeons (Acipenser baerii) reared on two different farms in Spain. Although a high degree of interindividual variability was observed, certain differences between the anatomical parts and between the geographical locations were clear. The results show that the sequences corresponding to the most abundant taxa were the basis for clustering according to anatomical region (proximal and distal intestine), whereas the less abundant taxa were the basis for clustering according to the geographical location of the fish farms. Finally, the results also indicate the existence of certain bacteria that are present in the intestinal tracts of all the fish analyzed in this study; this information may be useful in future studies aiming to establish differences based upon fish health or disease

Chiral Heat Wave and mixing of Magnetic, Vortical and Heat waves in chiral media

We show that a hot rotating fluid of relativistic chiral fermions possesses a new gapless collective mode associated with coherent propagation of energy density and chiral density waves along the axis of rotation. This mode, which we call the Chiral Heat Wave, emerges due to a mixed gauge-gravitational anomaly. At finite density the Chiral Heat Wave couples to the Chiral Vortical Wave while in the presence of an external magnetic field it mixes with the Chiral Magnetic Wave. The coupling of the Chiral Magnetic and Chiral Vortical Waves is also demonstrated. We find that the coupled waves - which are coherent fluctuations of the vector, axial and energy currents - have generally different velocities compared to the velocities of the individual waves.Comment: 33 pages, 6 figures; v2: minor changes, published versio

Estudo de Solos do Município de Erval Seco, RS.

bitstream/item/46946/1/circular-111.pdf; bitstream/item/46947/1/ErvalSeco-aptidaoagricola93.pdf; bitstream/item/46948/1/ErvalSeco-capacidadeuso93.pdf; bitstream/item/46950/1/ErvalSeco-relevo93.pdf; bitstream/item/46951/1/ErvalSeco-solos93.pd

Estudos de Solos do Município de Frederico Westphalen, RS.

bitstream/item/45561/1/CIRCULAR-TECNICA-116.pdf; bitstream/item/45562/1/FredericoWestphalen-aptidaoagricola.pdf; bitstream/item/45563/1/FredericoWestphalen-capacidadedeuso.pdf; bitstream/item/45564/1/FredericoWestphalen-relevo2.pdf; bitstream/item/45565/1/FredericoWestphalen-solos.pd

Positivity, entanglement entropy, and minimal surfaces

The path integral representation for the Renyi entanglement entropies of integer index n implies these information measures define operator correlation functions in QFT. We analyze whether the limit $n\rightarrow 1$, corresponding to the entanglement entropy, can also be represented in terms of a path integral with insertions on the region's boundary, at first order in $n-1$. This conjecture has been used in the literature in several occasions, and specially in an attempt to prove the Ryu-Takayanagi holographic entanglement entropy formula. We show it leads to conditional positivity of the entropy correlation matrices, which is equivalent to an infinite series of polynomial inequalities for the entropies in QFT or the areas of minimal surfaces representing the entanglement entropy in the AdS-CFT context. We check these inequalities in several examples. No counterexample is found in the few known exact results for the entanglement entropy in QFT. The inequalities are also remarkable satisfied for several classes of minimal surfaces but we find counterexamples corresponding to more complicated geometries. We develop some analytic tools to test the inequalities, and as a byproduct, we show that positivity for the correlation functions is a local property when supplemented with analyticity. We also review general aspects of positivity for large N theories and Wilson loops in AdS-CFT.Comment: 36 pages, 10 figures. Changes in presentation and discussion of Wilson loops. Conclusions regarding entanglement entropy unchange