153,571 research outputs found
Serum ACTH and Cortisol Level is Associated with the Acute Gastrointestinal Injury Grade in ICU Patients [Erratum]
No full textXu W, Qiu Y, Qiu H, Zhong M, Li L. Int J Gen Med. 2024;17:127–134.
On page 127, the third author’s name should read from “Hongping Qiu” to “Hongping Qu”.
This error was introduced by the Editorial staff during the publication process
A seat-occupant model for the prediction of backrest transmissibility in the fore-and-aft direction
No full textCross-axis apparent mass of the seated human body during single-axis and dual-axis vibration
No full text
Transmission of roll, pitch and yaw vibration to the backrest of a seat supported on a non-rigid car floor
No full textThe transmission of roll, pitch and yaw vibration from the floor of a small car to the seat backrest has been investigated with three road conditions. At the seat base, there were distinctive differences between roll vibration at the front and rear of the seat base and between pitch vibration at the left- and right-hand side of the seat base. The yaw motion was generally small relative to the roll and pitch motion. At high frequencies, the yaw motion calculated from the difference between fore-aft vibration at the left- and right-hand side of the seat base was less than the yaw motion calculated from the differences between lateral vibration at the front and back of the seat base. Furthermore, yaw motion calculated from the difference in lateral vibration at the right-hand side of the seat was greater than that at the left-hand side, due to differences between the two lateral accelerations at the two right corners of the seat base. The measurements indicated that the seat base was not a rigid structure in either roll, pitch or yaw.The transmission of rotational vibration from the non-rigid seat base to fore-and-aft, lateral and vertical vibration at the seat backrest was investigated using single- and multi-input models. It was found that pitch and roll vibration, together with translational vibration at the seat base, made significant contributions to seat backrest vibration. For predicting seat transmissibility in the fore-aft and vertical directions, a translational model comprising all the least-correlated fore-aft and vertical inputs, and a combined rotational and translational model consisting of the pitch vibration input and part of the least-correlated fore-aft and vertical inputs appeared equally good. Low coherency in the transmission of vibration to the lateral direction of the seat backrest observed when considering only translational vibration at the seat base was resolved after taking into account the effect of the roll vibration at the seat base
Transmission of vibration to the backrest of a car seat evaluated with multi-input models
No full textThe transmission of vibration to the occupant of a car seat has been studied using the multiple vibration inputs to the seat. Twelve input signals at the seat base (tri-axial vibration at the four corners) and six output signals (tri-axial vibration at the backrest and seat pan) were measured while driving. The results showed that vibration inputs to the seat varied between the four positions at the seat base. The two fore-aft input accelerations at the left-hand side of the seat base and the two fore-aft input accelerations at the right-hand side of the seat base were highly correlated with each other. There was also a high correlation between the two pairs of lateral acceleration inputs at the front and rear of the seat base. A computer program for studying seat vibration transmission via multi-input channels was developed to allow the calculation of seat transmissibility with up to 12 different inputs. The transmission of multi-axis seat base vibration to fore-aft seat backrest vibration was investigated using single-input, two-input, six-input and eight-input models. Results showed that the fore-aft vibration and the vertical vibration, but not lateral vibration, at the four corners of the seat base contributed to fore-aft vibration of the backrest. The primary peak of the fore-aft backrest transmissibility occurred around 4–5 Hz. The coherency was improved when using the multi-input models, although the characteristics of the transmissibility remained similar. The transmission of lateral vibration at the seat base to lateral vibration at the backrest was studied using single-input and two-input models. With single-input models, the transmission of lateral acceleration at the seat base to lateral acceleration at the backrest was amplified between 18 and 35 Hz, with a peak at 26 Hz. Coherency was greater at frequencies above 20 Hz than at lower frequencies. The coherency at low frequencies was increased with a two-input model. The transmission of vertical vibration to vertical vibration at the backrest was investigated using single-input, four-input and six-input models. The results showed that vertical acceleration at the four corners of the seat base was highly correlated with vertical acceleration at the backrest. The results are consistent with previous findings that a single-input model is not sufficient to study the transmission of vibration to the seat back in the horizontal directions, while for the transmission of vertical vibration a single-input model is probably sufficient, especially when low frequencies are of main concern
Revealing extraordinary properties of femtosecond laser writing in glass
No full textModification of transparent materials with ultrafast lasers has attracted considerable interest due to a wide range of applications including laser surgery, integrated optics, optical data storage, 3D micro- and nano-structuring [1].Three different types of material modifications can be induced with ultrafast laser irradiation in the bulk of a transparent material, silica glass in particular: an isotropic refractive index change (type 1); a form birefringence associated with self-assembled nanogratings and negative refractive index change (type 2) [2,3]; and a void (type 3). In fused silica the transition from type 1 to type 2 and finally to type 3 modification is observed with an increase of fluence. Recently, a remarkable phenomenon in ultrafast laser processing of transparent materials has been reported manifesting itself as a change in material modification by reversing the writing direction [4]. The phenomenon has been interpreted in terms of anisotropic plasma heating by a tilted front of the ultrashort laser pulse. Moreover a change in structural modification has been demonstrated in glass by controlling the direction of pulse front tilt, achieving a calligraphic style of laser writing which is similar in appearance to that inked with the bygone quill pen [5]. It has also been a common belief that in a homogeneous medium, the photosensitivity and corresponding light-induced material modifications do not change on the reversal of light propagation direction. More recently it have observed that in a noncentrosymmetric medium, modification of the material can be different when light propagates in opposite directions (KaYaSo effect) [6]. Non-reciprocity is produced by magnetic field (Faraday effect) and movement of the medium with respect to the direction of light propagation: parallel (Sagnac effect) or perpendicular (KaYaSo effect). Moreover a new phenomenon of ultrafast light blade, representing itself the first evidence of anisotropic sensitivity of isotropic medium to femtosecond laser radiation has been recently discovered [7]. We attribute these new phenomena to the anisotropy of the light-matter interaction caused by space-time couplings in ultrashort light pulses. This intrinsic spatio-temporal asymmetry of light opens an interesting opportunity in the control of photon flux interacting with a target submerged into condensed isotropic medium. We anticipate that the observed phenomena will open new opportunities in laser material processing, laser surgery, optical manipulation and data storage
Material processing using ultrashort light pulses with tilted front
No full textFemtosecond laser writing in glass is controlled by the polarization plane azimuth and intensity front tilt of light pulse. Polarization dependent distribution of extraordinary modifications along the light propagation direction is observed
Biodynamic response of the seated human body to single-axis and dual-axis vibration: effect of backrest and non-linearity
No full textThe biodynamic responses to the human body give an understanding of why human responses to vibration (changes in health, comfort, and performance) vary with the frequency and direction of vibration. Studies have shown that biodynamic responses also vary with the magnitude of vibration and that the backrests of seats influence the transmission of vibration to the seated human body. There has been little study of the nonlinearity in the biodynamic responses of the body to dual-axis excitation and no study of the influence of backrests during dual-axis excitation. This study investigated the apparent mass and cross-axis apparent mass of the human body exposed to random vibration (0.2 to 20 Hz) in all 15 possible combinations of four magnitudes (0, 0.25, 0.5 and 1.0 ms(-2) r.m.s.) of fore-and-aft vibration and the same four magnitudes of vertical vibration. Nonlinearity was evident, with the body softening with increasing magnitude of vibration when using a fixed magnitude of vibration in one direction and varying the magnitude of vibration in the other direction. The fore-and-aft apparent mass on the seat was greater without a backrest at the lower frequencies but greater with a backrest at the higher frequencies. The vertical apparent mass on the seat was decreased by the backrest at low frequencies. Cross-axis coupling was evident, with excitation in one axis producing a response in the other axis. It is concluded that the nonlinearity of the body evident during single-axis and multi-axis vibration, and the influence of backrests, should be taken into account when determining frequency weightings for predicting human responses to vibration and when optimising the dynamics of seating to minimise exposure to vibration
Sublytic complement C5b-9 complexes induce thrombospondin-1 production in rat glomerular mesangial cells via PI3-k/Akt: association with activation of latent transforming growth factor-beta1
No full textMesangial cell proliferation is a common cellular response to a variety of different types of glomerular injury. Complement C5b‐9 is a prime candidate to mediate mesangial cell proliferation, especially sublytic C5b‐9, which can induce the production of multiple inflammatory factors and cytokines. Transforming growth factor (TGF)‐β1 plays a major role in the accumulation of extracellular matrix (ECM), while thrombospondin (TSP)‐1 has been identified as an activator of latent TGF‐β1 in an in vitro system. Using rat glomerular mesangial cells (GMCs) as a model system, we assessed the effect of sublytic C5b‐9 on the expression of TSP‐1 and TGF‐β1 and explored the relevant pathway of signal transduction. First, we ensured the concentrations of anti‐Thy1 antibody and complement, which were regarded as a sublytic C5b‐9 dose, and examined whether the sublytic C5b‐9 induced expression of TSP‐1 in rat GMCs which, in turn, activated latent TGF‐β1 by real‐time polymerase chain reaction (PCR) and enzyme‐linked immunosorbent assay (ELISA), respectively. Then, we investigated the role of the PI3‐k/Akt pathway in sublytic C5b‐9‐induced TSP‐1 production in rat GMCs by Western blot analysis. The addition of sublytic C5b‐9 (5% anti‐Thy1 antibody and 4% normal serum) to rat GMCs induced activation of latent TGF‐β1 via TSP‐1. The addition of sublytic C5b‐9 apparently increased the protein of Akt phosphorylation, whereas PI3‐k inhibitor LY294002 could clearly reduce the increase of TSP‐1 induced by sublytic C5b‐9. These results indicate that TSP‐1 is an activator of latent TGF‐β1 in sublytic C5b‐9‐induced rat GMCs; furthermore, the PI3‐k/Akt signal transduction pathway may play a key role in sublytic C5b‐9‐induced TSP‐1 production
- …
