COVID-19 which is caused by its new type called SARS-CoV-2 is a viral disease predominantly involving the lungs. <b>Objective:</b> To investigate HRCT features of pulmonary disease in COVID-19 in Lahore, P...COVID-19 which is caused by its new type called SARS-CoV-2 is a viral disease predominantly involving the lungs. <b>Objective:</b> To investigate HRCT features of pulmonary disease in COVID-19 in Lahore, Pakistan. <b>Methods:</b> This is a prospective study that involved 127 COVID-19 positive patients (age 18 - 80 years, both genders) through non-probability sampling was conducted at the Radiology Department, Sir Ganga Ram Hospital, Lahore, in 2021. All patients with RT-PCR positive underwent HRCT chest. All findings in HRCT chest were assessed. Confirmed patients had positive HRCT. Excluded situations are low quality of images irrespective of its reason, HRCT indications other than COVID-19 pneumonia, and patients who do not want to participate in the study <b>Results:</b> Considering the exclusion and inclusion criteria, totally 127 COVID-19 confirmed patients ranging age from 18 to 80 years with a mean age of 52 ± 18 years, took part in this study. The most important and common HRCT finding was the multilobar ground-glass pattern which was present in 95% of patients. Other findings including, crazy paving pattern, consolidation, air bronchogram, and bronchiectasis were present in 8.7%, 82%, 63%, and 37% of patients respectively. Pleural effusion seen in 21% patients. 16% of patients had mediastinal lymphadenopathy. <b>Conclusion:</b> In our study, the ground-glass pattern was found to be the most common and important HRCT finding in patients confirmed with COVID-19 pneumonia. This important HRCT pattern is mostly found to be in posterobasal and peripheral subpleural locations. Other than ground-glass pattern, bronchiectasis, and consolidation having the air bronchogram were also reported commonly.展开更多
COVID-19 is a respiratory infection that has lately begun to affect other vital organs,including the heart,kidney,and liver.The purpose of this study was to investigate the hepatic complications in COVID-19 patients a...COVID-19 is a respiratory infection that has lately begun to affect other vital organs,including the heart,kidney,and liver.The purpose of this study was to investigate the hepatic complications in COVID-19 patients and the risk of being admitted to ICU or facing death.Methodology:Comorbidities(hypertension and diabetes),COVID-19 symptoms,laboratory findings(ALT level,AST level,and albumin),complications during hospitalization,treatment protocol used,and survival outcomes were all studied in 200 COVID-19 infected Egyptian patients who had virological symptoms and were followed up until they recovered or died.It was found that older people and those with higher blood glucose levels have a higher risk of developing liver-associated COVID-19 disorders.Also,the majority of patients who developed liver complications in the course of the infection had high mortality rates.Patients with diabetes,hypertension,or hepatic disease are at higher risk of ICU admission or death.Hence,it is important to pay attention to these problems in the diagnosis and treatment of COVID-19 to develop a suitable individualized treatment protocol.There was also a correlation between the mortality in COVID-19 patients and both,high blood glucose and liver enzyme levels.It can be attributed to the correlation between diabetes and liver disease as every disease may be a complication to the other;moreover,COVID-19 may lead to increased blood sugar levels in addition to ALT and AST levels.Another theory is that COVID-19 may afiect the liver and hence people with chronic liver disease.展开更多
未来学代表作The Third Wave于20世纪80年代初译介入中国,曾在社会上掀起阅读热潮和广泛影响,是典型社会时期具有代表性的翻译案例,但至今鲜有翻译方向的学者关注。在此书译介30周年之际,针对The Third Wave首个中译本出现之前的译介活...未来学代表作The Third Wave于20世纪80年代初译介入中国,曾在社会上掀起阅读热潮和广泛影响,是典型社会时期具有代表性的翻译案例,但至今鲜有翻译方向的学者关注。在此书译介30周年之际,针对The Third Wave首个中译本出现之前的译介活动、海峡两岸译本情况进行介绍和梳理,考证《第三次浪潮》说法的起源,并分析此书引发阅读热潮的原因和译语社会对此书的接受和批评情况。展开更多
Compared to conditions during the early months of the global financial crisis,today’s world is experiencing new recession-related symptoms-price hikes of agricultural products and other major commodities,and currency...Compared to conditions during the early months of the global financial crisis,today’s world is experiencing new recession-related symptoms-price hikes of agricultural products and other major commodities,and currency appreciations in emerging economies,to name a few.Sun展开更多
Based on the Stokes wave theory, the capillary-gravity wave and the interfacial internal wave in two-layer constant depth＇s fluid system are investigated. The fluids are assumed to be incompressible, inviscid and irr...Based on the Stokes wave theory, the capillary-gravity wave and the interfacial internal wave in two-layer constant depth＇s fluid system are investigated. The fluids are assumed to be incompressible, inviscid and irrotational. The third-order Stokes wave solutions are given by using a perturbation method. The results indicate that the third-order solutions depend on the surface tension, the density and the depth of each layer. As expected, the first-order solutions are the linear theoretical results （the small amplitude wave theoretical results）. The second-order and the third-order solutions describe the nonlinear modification and the nonlinear interactions. The nonlinear impact appears not only in the n （n〉~2） times＇ high frequency components, but also in the low frequency components. It is also noted that the wave velocity depends on the wave number, depth, wave amplitude and surface tension.展开更多
Interracial internal waves in a three-layer density-stratified fluid are investigated using a singular perturbation method, and third-order asymptotic solutions of the velocity potentials and third-order Stokes wave s...Interracial internal waves in a three-layer density-stratified fluid are investigated using a singular perturbation method, and third-order asymptotic solutions of the velocity potentials and third-order Stokes wave solutions of the associated elevations of the interfacial waves are presented based on the small amplitude wave theory. As expected, the third-order solutions describe the third-order nonlinear modification and the third-order nonlinear interactions between the interracial waves. The wave velocity depends on not only the wave number and the depth of each layer but also on the wave amplitude.展开更多
The existing numerical models for nearshore waves are briefly introduced, and the third-generation numerical model for shallow water wave, which makes use of the most advanced productions of wave research and has been...The existing numerical models for nearshore waves are briefly introduced, and the third-generation numerical model for shallow water wave, which makes use of the most advanced productions of wave research and has been adapted well to be used in the environment of seacoast, lake and estuary area, is particularly discussed. The applied model realizes the significant wave height distribution at different wind directions. To integrate the model into the coastal area sediment, sudden deposition mechanism, the distribution of average silt content and the change of sediment sudden deposition thickness over time in the nearshore area are simulated. The academic productions can give some theoretical guidance to the applications of sediment sudden deposition mechanism for stormy waves in the coastal area. And the advancing directions of sediment sudden deposition model are prospected.展开更多
The unprecedented healthcare demand due to sudden outbreak of coronavirus disease 2019 (COVID-19) pandemic has almost collapsed the health care systems especially in the developing world. Given the disastrous outbreak...The unprecedented healthcare demand due to sudden outbreak of coronavirus disease 2019 (COVID-19) pandemic has almost collapsed the health care systems especially in the developing world. Given the disastrous outbreak of COVID-19 second wave in India, the health system of country was virtually at the brink of collapse. Therefore, to identify the factors that resulted into breakdown and the challenges, Indian healthcare system faced during the second wave of COVID-19 pandemic, this paper analysed the health system challenges in India and the way forward in accordance with the six building blocks of world health organization (WHO). Applying integrated review approach, we found that the factors such as poor infrastructure, inadequate financing, lack of transparency and poor healthcare management resulted into the overstretching of healthcare system in India. Although health system in India faced these challenges from the very beginning, but early lessons from first wave should have been capitalized to avert the much deeper crisis in the second wave of the pandemic. To sum-up given the likely future challenges of pandemic, while healthcare should be prioritized with adequate financing, strong capacity-building measures and integration of public and private sectors in India. Likewise fiscal stimulus, risk assessment, data availability and building of human resources chain are other key factors to be strengthened for mitigating the future healthcare crisis in country.展开更多
The optical wave breaking （OWB） characteristics in terms of the pulse shape, spectrum, and frequency chirp, in the normal dispersion regime of an optical fiber with both the third-order dispersion （TOD） and quinti...The optical wave breaking （OWB） characteristics in terms of the pulse shape, spectrum, and frequency chirp, in the normal dispersion regime of an optical fiber with both the third-order dispersion （TOD） and quintic nonlinearity （QN） are numerically calculated. The results show that the TOD causes the asymmetry of the temporal- and spectral-domain, and the chirp characteristics. The OWB generally appears near the pulse center and at the trailing edge of the pulse, instead of at the two edges of the pulse symmetrically in the case of no TOD. With the increase of distance, the relation of OWB to the TOD near the pulse center increases quickly, leading to the generation of ultra-short pulse trains, while the OWB resulting from the case of no TOD at the trailing edge of the pulse disappears gradually. In addition, the positive （negative） QN enhances （weakens） the chirp amount and the fine structures, thereby inducing the OWB phenomena to appear earlier （later）. Thus, the TOD and the positive （negative） QN are beneficial （detrimental） to the OWB and the generation of ultra-short pulse trains.展开更多
A novel soluble π-conjugated polymer, poly [（3-acetylpyrrole-2, 5-diyl） p-（N, N-dimethylamino） azobenzylidene] （PAPDMAABE）, was synthesized by condensation of 3-acetylpyrrole with 4-aldehyde-4＇-dimethylaminoaz...A novel soluble π-conjugated polymer, poly [（3-acetylpyrrole-2, 5-diyl） p-（N, N-dimethylamino） azobenzylidene] （PAPDMAABE）, was synthesized by condensation of 3-acetylpyrrole with 4-aldehyde-4＇-dimethylaminoazobenzene （ADMAA）. The chemical structure of PAPDMAABE was characterized by Fourier transform infrared spectroscopy （FTIR）, ^1H-NMR, and UV-Vis-NIR spectra. Transmission electron microscope （TEM） analysis for PAPDMAABE indicates that part of PAPDMAABE is in crystal state, due to the short-range order of the polymer. Thermogravimetric analysis （TGA） curve shows that the polymer has good thermal stability and its decomposition temperature is 248℃. The optical band gap of PAPDMAABE obtained from the optical absorption spectrum is about 1.73 eV. The resonant third-order nonlinear optical property of PAPDMAABE at 532 nm was studied using degenerate four-wave mixing （DFWM） technique. The resonant third-order nonlinear optical susceptibility of the polymer is about 7.48×10^-8 esu.展开更多
The fully oxidized state of polyaniline (PANI), pernigraniline (PN), was synthesized by oxidation of the emeraldine base form of PAM dissolved in NMP solvent with m-chloroperoxybenzoic acid. The resulted PN was charac...The fully oxidized state of polyaniline (PANI), pernigraniline (PN), was synthesized by oxidation of the emeraldine base form of PAM dissolved in NMP solvent with m-chloroperoxybenzoic acid. The resulted PN was characterized by FTIR and UV-Visible spectra. The third-order nonlinear optical properties of PN in concentrated sulfuric acid (PN/H2SO4) were measured by a degenerated four wave mixing (DFWM) method. The results obtained suggest that the soliton-pair intermediate state associated with the degenerated state does not play a major role in the third order nonlinear optical properties of PANI.展开更多
As is well known, hand-arm vibration syndrome (HAVS), or vibration-induced white finger (VWF), which is a secondary form of Raynaud’s syndrome, is an industrial injury triggered by regular use of vibrating hand-held ...As is well known, hand-arm vibration syndrome (HAVS), or vibration-induced white finger (VWF), which is a secondary form of Raynaud’s syndrome, is an industrial injury triggered by regular use of vibrating hand-held tools. According to the related biopsy tests, the main vibration-caused lesion is an increase in the thickness of the artery walls of the small arteries and arterioles resulted from enlarged vascular smooth muscle cells (VSMCs) in the wall layer known as tunica media. The present work develops a mechanobiological picture for the cell enlargement. The work deals with acoustic variables in solid materials, i.e., the non-equilibrium components of mechanical variables in the materials in the case where these components are weakly non-equilibrium. The work derives an explicit expression for the infinite-time cell-volume relative enlargement. This enlargement is directly affected by the acoustic pressure in the soft living tissue (SLT). In order to reduce the enlargement, one can reduce either the ratio of the acoustic pressure in the SLT to the cell bulk modulus or the relaxation time induced by the cell osmosis, or both the characteristics. Also, a mechanoprotective role of the above relaxation time in the cell-volume maintenance is noted. The above mechanobiological picture focuses attention on the pressure in an SLT and, thus, modeling of propagation of acoustic waves caused by the acceleration of a vibrating hand-held tool. The present work analyzes the propagation along the thickness of an infinite planar layer of an SLT. The work considers acoustic modeling. As a general viscoelastic acoustic model, the work suggests linear non-stationary partial integro-differential equation (PIDE) for the weakly non-equilibrium component of the average normal stress (ANS) or, briefly, the acoustic ANS. The PIDE is, in the exponential approximation for the normalized stress-relaxation function (NSRF) reduced to the third-order linear non-stationary partial differential equation (PDE), which is of the Zener type. The unique advantage of the PIDE is that it presents a compact model for the acoustic ANS in an SLT, which explicitly includes the NSRF, thereby enabling a consistent description of the lossy-propagation effects inherent in SLTs. The one-spatial-coordinate version of this PDE in the planar SLT layer with the corresponding boundary conditions is considered. The relevance of these settings is motivated by a conclusion of other authors, which is based on the results of the frequency-domain simulation in three spatial coordinates. The boundary-value problem at arbitrary value of the stress-relaxation time (SRT) and arbitrary but sufficiently regular shape of the external acceleration is analytically solved by means of the Fourier method. The obtained solution is the steady-state acoustic ANS and allows calculation of the corresponding steady-state acoustic pressure as well. The derived analytical representations are computationally implemented. Propagation of the pressure waves in the SLT layer at zero and different nonzero values of the SRT, and the single-pulse external acceleration is presented. They complement the zero-SRT and zero-SRT-asymptote results with the results for various values of the SRT. The obtained pressure values are, at all of the space-time points under consideration, meeting the condition for the adequateness of the linear model. In the case where the SRT is zero, the results well agree with the ones obtained by using the simulation software package LS-DYNA. The dependence of the damping of acoustic variables in an SLT on the SRT in the present third-order case significantly generalizes the one in the second-order linear systems. The related resonance effect in the waves of the acoustic pressure propagating in an SLT is also discussed. The effects of the NSRF-originated memory function provided by the present third-order PDE model are necessary for proper simulation of the pressure, which is of special importance in the aforementioned mechanoboiological picture. The results obtained in the work present a viscoelastic acoustic framework for SLTs. These results open a way to quantitatively specific evaluation of technological strategies for reduction of the vibration-caused injuries or, loosely speaking, achieving “zero’’ injury.展开更多
文摘COVID-19 which is caused by its new type called SARS-CoV-2 is a viral disease predominantly involving the lungs. <b>Objective:</b> To investigate HRCT features of pulmonary disease in COVID-19 in Lahore, Pakistan. <b>Methods:</b> This is a prospective study that involved 127 COVID-19 positive patients (age 18 - 80 years, both genders) through non-probability sampling was conducted at the Radiology Department, Sir Ganga Ram Hospital, Lahore, in 2021. All patients with RT-PCR positive underwent HRCT chest. All findings in HRCT chest were assessed. Confirmed patients had positive HRCT. Excluded situations are low quality of images irrespective of its reason, HRCT indications other than COVID-19 pneumonia, and patients who do not want to participate in the study <b>Results:</b> Considering the exclusion and inclusion criteria, totally 127 COVID-19 confirmed patients ranging age from 18 to 80 years with a mean age of 52 ± 18 years, took part in this study. The most important and common HRCT finding was the multilobar ground-glass pattern which was present in 95% of patients. Other findings including, crazy paving pattern, consolidation, air bronchogram, and bronchiectasis were present in 8.7%, 82%, 63%, and 37% of patients respectively. Pleural effusion seen in 21% patients. 16% of patients had mediastinal lymphadenopathy. <b>Conclusion:</b> In our study, the ground-glass pattern was found to be the most common and important HRCT finding in patients confirmed with COVID-19 pneumonia. This important HRCT pattern is mostly found to be in posterobasal and peripheral subpleural locations. Other than ground-glass pattern, bronchiectasis, and consolidation having the air bronchogram were also reported commonly.
文摘COVID-19 is a respiratory infection that has lately begun to affect other vital organs,including the heart,kidney,and liver.The purpose of this study was to investigate the hepatic complications in COVID-19 patients and the risk of being admitted to ICU or facing death.Methodology:Comorbidities(hypertension and diabetes),COVID-19 symptoms,laboratory findings(ALT level,AST level,and albumin),complications during hospitalization,treatment protocol used,and survival outcomes were all studied in 200 COVID-19 infected Egyptian patients who had virological symptoms and were followed up until they recovered or died.It was found that older people and those with higher blood glucose levels have a higher risk of developing liver-associated COVID-19 disorders.Also,the majority of patients who developed liver complications in the course of the infection had high mortality rates.Patients with diabetes,hypertension,or hepatic disease are at higher risk of ICU admission or death.Hence,it is important to pay attention to these problems in the diagnosis and treatment of COVID-19 to develop a suitable individualized treatment protocol.There was also a correlation between the mortality in COVID-19 patients and both,high blood glucose and liver enzyme levels.It can be attributed to the correlation between diabetes and liver disease as every disease may be a complication to the other;moreover,COVID-19 may lead to increased blood sugar levels in addition to ALT and AST levels.Another theory is that COVID-19 may afiect the liver and hence people with chronic liver disease.
文摘未来学代表作The Third Wave于20世纪80年代初译介入中国,曾在社会上掀起阅读热潮和广泛影响,是典型社会时期具有代表性的翻译案例,但至今鲜有翻译方向的学者关注。在此书译介30周年之际,针对The Third Wave首个中译本出现之前的译介活动、海峡两岸译本情况进行介绍和梳理,考证《第三次浪潮》说法的起源,并分析此书引发阅读热潮的原因和译语社会对此书的接受和批评情况。
文摘Compared to conditions during the early months of the global financial crisis,today’s world is experiencing new recession-related symptoms-price hikes of agricultural products and other major commodities,and currency appreciations in emerging economies,to name a few.Sun
基金financially supported by the Science Research Project of Inner Mongolia University of Technology,China(Grant No.ZD201613)
文摘Based on the Stokes wave theory, the capillary-gravity wave and the interfacial internal wave in two-layer constant depth＇s fluid system are investigated. The fluids are assumed to be incompressible, inviscid and irrotational. The third-order Stokes wave solutions are given by using a perturbation method. The results indicate that the third-order solutions depend on the surface tension, the density and the depth of each layer. As expected, the first-order solutions are the linear theoretical results （the small amplitude wave theoretical results）. The second-order and the third-order solutions describe the nonlinear modification and the nonlinear interactions. The nonlinear impact appears not only in the n （n〉~2） times＇ high frequency components, but also in the low frequency components. It is also noted that the wave velocity depends on the wave number, depth, wave amplitude and surface tension.
基金supported by the Natural Science Foundation of Inner Mongolia,China(Grant No 200711020116)Open Fund of the Key Laboratory of Ocean Circulation and Waves,Chinese Academy of Sciences(Grant No KLOCAW0805)+1 种基金the Key Program of the Scientific Research Plan of Inner Mongolia University of Technology,China(Grant No ZD200608)National Science Fund for Distinguished Young Scholars of China(Grant No 40425015)
文摘Interracial internal waves in a three-layer density-stratified fluid are investigated using a singular perturbation method, and third-order asymptotic solutions of the velocity potentials and third-order Stokes wave solutions of the associated elevations of the interfacial waves are presented based on the small amplitude wave theory. As expected, the third-order solutions describe the third-order nonlinear modification and the third-order nonlinear interactions between the interracial waves. The wave velocity depends on not only the wave number and the depth of each layer but also on the wave amplitude.
文摘The existing numerical models for nearshore waves are briefly introduced, and the third-generation numerical model for shallow water wave, which makes use of the most advanced productions of wave research and has been adapted well to be used in the environment of seacoast, lake and estuary area, is particularly discussed. The applied model realizes the significant wave height distribution at different wind directions. To integrate the model into the coastal area sediment, sudden deposition mechanism, the distribution of average silt content and the change of sediment sudden deposition thickness over time in the nearshore area are simulated. The academic productions can give some theoretical guidance to the applications of sediment sudden deposition mechanism for stormy waves in the coastal area. And the advancing directions of sediment sudden deposition model are prospected.
文摘The unprecedented healthcare demand due to sudden outbreak of coronavirus disease 2019 (COVID-19) pandemic has almost collapsed the health care systems especially in the developing world. Given the disastrous outbreak of COVID-19 second wave in India, the health system of country was virtually at the brink of collapse. Therefore, to identify the factors that resulted into breakdown and the challenges, Indian healthcare system faced during the second wave of COVID-19 pandemic, this paper analysed the health system challenges in India and the way forward in accordance with the six building blocks of world health organization (WHO). Applying integrated review approach, we found that the factors such as poor infrastructure, inadequate financing, lack of transparency and poor healthcare management resulted into the overstretching of healthcare system in India. Although health system in India faced these challenges from the very beginning, but early lessons from first wave should have been capitalized to avert the much deeper crisis in the second wave of the pandemic. To sum-up given the likely future challenges of pandemic, while healthcare should be prioritized with adequate financing, strong capacity-building measures and integration of public and private sectors in India. Likewise fiscal stimulus, risk assessment, data availability and building of human resources chain are other key factors to be strengthened for mitigating the future healthcare crisis in country.
基金supported by the Postdoctoral Fund of China(Grant No.2011M501402)the National Natural Science Foundation of China(Grant No.61275039)+2 种基金the 973 Program of China(Grant No.2012CB315702)the Key Project of the Chinese Ministry of Education,China(Grant No.210186)the Major Project of the Natural Science Foundation supported by the Educational Department of Sichuan Province,China(Grant Nos.13ZA0081 and 12ZB019)
文摘The optical wave breaking （OWB） characteristics in terms of the pulse shape, spectrum, and frequency chirp, in the normal dispersion regime of an optical fiber with both the third-order dispersion （TOD） and quintic nonlinearity （QN） are numerically calculated. The results show that the TOD causes the asymmetry of the temporal- and spectral-domain, and the chirp characteristics. The OWB generally appears near the pulse center and at the trailing edge of the pulse, instead of at the two edges of the pulse symmetrically in the case of no TOD. With the increase of distance, the relation of OWB to the TOD near the pulse center increases quickly, leading to the generation of ultra-short pulse trains, while the OWB resulting from the case of no TOD at the trailing edge of the pulse disappears gradually. In addition, the positive （negative） QN enhances （weakens） the chirp amount and the fine structures, thereby inducing the OWB phenomena to appear earlier （later）. Thus, the TOD and the positive （negative） QN are beneficial （detrimental） to the OWB and the generation of ultra-short pulse trains.
基金the National Natural Science Foundation of China for financial support of this work(No.60277002).
文摘A novel soluble π-conjugated polymer, poly [（3-acetylpyrrole-2, 5-diyl） p-（N, N-dimethylamino） azobenzylidene] （PAPDMAABE）, was synthesized by condensation of 3-acetylpyrrole with 4-aldehyde-4＇-dimethylaminoazobenzene （ADMAA）. The chemical structure of PAPDMAABE was characterized by Fourier transform infrared spectroscopy （FTIR）, ^1H-NMR, and UV-Vis-NIR spectra. Transmission electron microscope （TEM） analysis for PAPDMAABE indicates that part of PAPDMAABE is in crystal state, due to the short-range order of the polymer. Thermogravimetric analysis （TGA） curve shows that the polymer has good thermal stability and its decomposition temperature is 248℃. The optical band gap of PAPDMAABE obtained from the optical absorption spectrum is about 1.73 eV. The resonant third-order nonlinear optical property of PAPDMAABE at 532 nm was studied using degenerate four-wave mixing （DFWM） technique. The resonant third-order nonlinear optical susceptibility of the polymer is about 7.48×10^-8 esu.
基金This work was partly supported by NNSFC,Chinese Academy of Sciences and Director Foundation of the Institute of Chemistry,Academia Sinica
文摘The fully oxidized state of polyaniline (PANI), pernigraniline (PN), was synthesized by oxidation of the emeraldine base form of PAM dissolved in NMP solvent with m-chloroperoxybenzoic acid. The resulted PN was characterized by FTIR and UV-Visible spectra. The third-order nonlinear optical properties of PN in concentrated sulfuric acid (PN/H2SO4) were measured by a degenerated four wave mixing (DFWM) method. The results obtained suggest that the soliton-pair intermediate state associated with the degenerated state does not play a major role in the third order nonlinear optical properties of PANI.
文摘As is well known, hand-arm vibration syndrome (HAVS), or vibration-induced white finger (VWF), which is a secondary form of Raynaud’s syndrome, is an industrial injury triggered by regular use of vibrating hand-held tools. According to the related biopsy tests, the main vibration-caused lesion is an increase in the thickness of the artery walls of the small arteries and arterioles resulted from enlarged vascular smooth muscle cells (VSMCs) in the wall layer known as tunica media. The present work develops a mechanobiological picture for the cell enlargement. The work deals with acoustic variables in solid materials, i.e., the non-equilibrium components of mechanical variables in the materials in the case where these components are weakly non-equilibrium. The work derives an explicit expression for the infinite-time cell-volume relative enlargement. This enlargement is directly affected by the acoustic pressure in the soft living tissue (SLT). In order to reduce the enlargement, one can reduce either the ratio of the acoustic pressure in the SLT to the cell bulk modulus or the relaxation time induced by the cell osmosis, or both the characteristics. Also, a mechanoprotective role of the above relaxation time in the cell-volume maintenance is noted. The above mechanobiological picture focuses attention on the pressure in an SLT and, thus, modeling of propagation of acoustic waves caused by the acceleration of a vibrating hand-held tool. The present work analyzes the propagation along the thickness of an infinite planar layer of an SLT. The work considers acoustic modeling. As a general viscoelastic acoustic model, the work suggests linear non-stationary partial integro-differential equation (PIDE) for the weakly non-equilibrium component of the average normal stress (ANS) or, briefly, the acoustic ANS. The PIDE is, in the exponential approximation for the normalized stress-relaxation function (NSRF) reduced to the third-order linear non-stationary partial differential equation (PDE), which is of the Zener type. The unique advantage of the PIDE is that it presents a compact model for the acoustic ANS in an SLT, which explicitly includes the NSRF, thereby enabling a consistent description of the lossy-propagation effects inherent in SLTs. The one-spatial-coordinate version of this PDE in the planar SLT layer with the corresponding boundary conditions is considered. The relevance of these settings is motivated by a conclusion of other authors, which is based on the results of the frequency-domain simulation in three spatial coordinates. The boundary-value problem at arbitrary value of the stress-relaxation time (SRT) and arbitrary but sufficiently regular shape of the external acceleration is analytically solved by means of the Fourier method. The obtained solution is the steady-state acoustic ANS and allows calculation of the corresponding steady-state acoustic pressure as well. The derived analytical representations are computationally implemented. Propagation of the pressure waves in the SLT layer at zero and different nonzero values of the SRT, and the single-pulse external acceleration is presented. They complement the zero-SRT and zero-SRT-asymptote results with the results for various values of the SRT. The obtained pressure values are, at all of the space-time points under consideration, meeting the condition for the adequateness of the linear model. In the case where the SRT is zero, the results well agree with the ones obtained by using the simulation software package LS-DYNA. The dependence of the damping of acoustic variables in an SLT on the SRT in the present third-order case significantly generalizes the one in the second-order linear systems. The related resonance effect in the waves of the acoustic pressure propagating in an SLT is also discussed. The effects of the NSRF-originated memory function provided by the present third-order PDE model are necessary for proper simulation of the pressure, which is of special importance in the aforementioned mechanoboiological picture. The results obtained in the work present a viscoelastic acoustic framework for SLTs. These results open a way to quantitatively specific evaluation of technological strategies for reduction of the vibration-caused injuries or, loosely speaking, achieving “zero’’ injury.
