Highly Configurable 100 Channel Recording and Stimulating Integrated Circuit for Biomedical Experiments

This paper presents the design results of a 100-channel integrated circuit dedicated to various biomedical experiments requiring both electrical stimulation and recording ability. The main design motivation was to develop an architecture that would comprise not only the recording and stimulation, but would also block allowing to meet different experimental requirements. Therefore, both the controllability and programmability were prime concerns, as well as the main chip parameters uniformity. The recording stage allows one to set their parameters independently from channel to channel, i.e., the frequency bandwidth can be controlled in the (0.3 Hz–1 kHz)–(20 Hz–3 kHz) (slow signal path) or (0.3 Hz–1 kHz)–4.7 kHz (fast signal path) range, while the voltage gain can be set individually either to 43.5 dB or 52 dB. Importantly, thanks to in-pixel circuitry, main system parameters may be controlled individually allowing to mitigate the circuitry components spread, i.e., lower corner frequency can be tuned in the 54 dB range with approximately 5% precision, and the upper corner frequency spread is only 4.2%, while the voltage gain spread is only 0.62%. The current stimulator may also be controlled in the broad range (69 dB) with its current setting precision being no worse than 2.6%. The recording channels’ input-referred noise is equal to 8.5 µVRMS in the 10 Hz–4.7 kHz bandwidth. The single-pixel occupies 0.16 mm2 and consumes 12 µW (recording part) and 22 µW (stimulation blocks).

Fluid-injection-induced earthquakes characterized by hybrid-frequency waveforms manifest the transition from aseismic to seismic slip

Aseismic slip loading has recently been proposed as a complementary mechanism to induce moderate-sized earthquakes located within a few kilometers of the wellbore over the timescales of hydraulic stimulation. However, aseismic slip signals linked to injection-induced earthquakes remain largely undocumented to date. Here we report a new type of earthquake characterized by hybrid-frequency waveforms (EHWs). Distinguishing features from typical induced earthquakes include broader P and S-pulses and relatively lower-frequency coda content. Both features may be causally related to lower corner frequencies, implying longer source durations, thus, either slower rupture speeds, lower stress drop values, or a combination of both. The source characteristics of EHWs are identical to those of low-frequency earthquakes widely documented in plate boundary fault transition zones. The distribution of EHWs further suggests a possible role of aseismic slip in fault loading. EHWs could thus represent the manifestation of slow rupture transitioning from aseismic to seismic slip.

Experimental investigations of interference effects on wind pressures of tall buildings

The interference effects between two tall buildings on building surface wind pressures are studied by using wind tunnel experiments. Different breadth ratios ( B r = B interfering/ Bprincipal), depth ratios ( D r = D interfering/ Dprincipal), and relative locations of the two buildings are tested. The results show that the interference effects on mean wind pressures on the windward face and the right face are more considerable than those on the other two faces. The windward face mainly shows the shielding effect, while the right face exhibits the amplification effect. The surface interference factors ( SIF) of windward and right faces under different breadth ratios and depth ratios have clear correlation with the reference values ( B r = D r = 1.0), and a series of correlation formulas are obtained. The SIF values of the windward face in tandem arrangement and the maximum and minimum interference factors of the right face in parallel arrangement are formulated. The most prominent local peak pressure under different cases mainly concentrates in the side edge and upper edge of the windward face, the left upper corner, left lower corner, and the upper-middle part of the right face.

Dynamic Evolution Law and Width Determination of Section Coal Pillars in Deep Mining Height Working Face

The coal column undergoes three types of force evolution from the formation to the end of mining. This paper takes large mining height working face at No.2 Coal Mine as example to study the ways to avoid dynamic instability of the coal column triggered by the deep mining. By means of geological survey, theoretical analysis, numerical calculation and field verification, the load processes under the three stress stage are proposed, and the evolution law of the coal column is analyzed. The study shows that the depth, large mining height working face, coal pillar force and size altogether determine the damage characteristics of the coal pillar. With the combination of Flac3D and 3DEC, it can be analyzed that the plastic failure and displacement characteristics of the 35m coal column under the action of secondary dynamic load coincide. The perturbation stress distribution is stable, which finally determines the reasonable width of the 35m coal column. Field measurements show that the top and gang of the 35m coal column undergo three kinds of displacement characteristics. The lower part is more stable. The top plate of the upper and lower corner completely collapsed in the emptying area, which can play a good supporting role.

Study through Geant4, for Time Resolution characterization of different detectors arrays coupled with two SiPMs, as a function of: the scintillator plastic material, its volumetric dimensions and the location of the radiation emission source

The high time resolution detectors are relevant in those experiments or simulations were the particles to detect, have a very short time of flight (TOF), and due this it´s required that the detections times are ranged between ns. & ps.Using Geant4 software, it was made thirty simulations of coupled detectors to plastic scintillators with two silicon photomultipliers (SiPMs) located on the scintillator’s central sides. To characterize the time resolution, it was required to quantify the optical photons that reach the Score in a certain time, which are generated by muons on the surface of the plastic scintillator. Different configurations of muon beams were simulated at energy of 1 GeV, to interact with the configuration of the scintillator material of its corresponding arrangement. The simulations were made varying three parameters: the scintillator material “BC404 & BC422”, its size, and the location of the radiation source. Fifteen simulations correspond to BC404 material & fifteen simulations to BC422 material respectively. The first five simulations consisted in varying the scintillator’s volumetric size and collocate the muons beam guided randomly distributed over it, the next five simulations differentiate from setting up a directly centered beam, and the last five simulations for guide the beam on the left lower corner of each scintillator.The best time resolution achieved was σ= 8.67 +/− 0.26 ps., reported by the detector with BC422 scintillator material which has a volume of 20x20x3 mm3.

Oxidation-induced three-dimensional morphological changes in Ni nanoparticles observed by coherent X-ray diffraction imaging

Three-dimensional structures of Ni nanoparticles undergoing significant morphological changes on oxidation were observed non-destructively using coherent X-ray diffraction imaging. The Ni particles were oxidized into Ni1O1 while forming pores of various sizes internally. For each Ni nanoparticle, one large void was identified at a lower corner near the interface with the substrate. The porosity of the internal region of the agglomerated Ni oxide was about 38.4%. Regions of high NiO density were mostly observed at the outer crust of the oxide or at the boundary with the large voids. This research expands our understanding of general catalytic reactions with direct observation of oxidation-induced nanoscale morphological changes.

Newly suggested shapes of impellers for stirring highly viscous fluids in vessels

The power consumption and flow patterns generated in a cylindrical stirred tank are determined. The anchor impeller is used to ensure the agitation of highly viscous fluids. Newly modifications in the impeller design are introduced to improve the stirring rates. Firstly, the lower corner of the conventional anchor is replaced by an inclined segment to obtain Case No. 1. The number of segments was then increased to reach a closed circular shape (Case No. 2). Further increase in the number of segments was introduced to reach a perfect circular blade (Case 3) in the vertical direction. Finally, another circular horizontal blade was added to obtain Case No. 4. From the obtained results, Case No. 4 provided a great improvement in the circulation of fluid particles inside the vessel and generated the widest well-stirred region.

Fluid-injection induced earthquakes characterized by hybrid-frequency waveforms manifest the transition from aseismic to seismic slip

Aseismic slip loading has recently been proposed as a complementary mechanism for moderate earthquakes (M3+) induced over the short operational period of hydraulic fracturing stimulations but located several kilometers away from the wellbore. However, aseismic/slow slip signals linked to fluid injection-induced earthquakes remain largely undocumented to date. Here we report a new type of induced seismic signal consisting of an impulsive broadband onset followed by protracted low-frequency ringing. Earthquakes characterized by hybrid-frequency waveforms (EHWs) differ from ordinary induced earthquakes by having broader P and S-pulses (implying longer source durations) and lower corner frequencies (implying either slower rupture speeds, lower stress drop values, or a combination of both). The characteristics described above are identical to low-frequency earthquakes found in plate boundary zones. EHWs could thus manifest the source process that bridges the slow (aseismic) slip inferred by recent modeling and observations near the wellbore to seismic slip at greater distances.

Bensinger. Schambeinschnitt ohne Knochennaht. (Centralblatt für Gynäkologie, No. 7, 1894). Symphysiotomy without bone suture

The author describes a case of symphysisotomy, without the use of a bone suture, which proceeded completely safely.The lig was not cut during the operation lig. arcuatum, but when the child was removed, it ruptured and the edges of the pubic bones parted to 6 cm. The child was extracted with forceps, alive. On the wound, 5 sutures were placed on the fascia and on the soft part, and anodoform drainage was carried out into the lower corner of the wound.

Shear Stress Distribution in the Opening Chords of Hybrid R/C T-Beams with Opening

This study is carried out to evaluate the potential of three hybrid T-beams with web openings theoretical shear stresses distribution. The shear stresses at the opening edges were plotted at the working stage, yielding stage and collapse stage for these three tested beams. The available experimental results from the previous research was compared to the finite element results as well as the developed analytical. The shear stress distribution at the middle of the top and bottom chords of the opening in pure bending region are zero. At the upper and lower corners of the opening occurs the maximum shear stresses. The maximum shear stress occurs at the right lower corner chord at the high moment edge and at the left upper corner chord at the low moment edge in beams with openings at high shear and high flexural – shear region. Furthermore, an extensive parametric study is performed on these beams to find the distributing ratio of the shear force between the opening chords. The shear force at an opening in hybrid R/C T-beam is carried by the top and bottom chords of the opening according to the area – moment of inertia root ratio with the correction factor 0.70.