Short-term fluctuation of intraocular pressure and influencing factors following intravitreal injection in patients with retinal vascular diseases

AIM:To investigate the patterns of short-term intraocular pressure(IOP)fluctuations and identify the contributing factors following intravitreal injection in patients with retinal vascular diseases.METHODS:Totally 81 patients were enrolled in this case control study.Eyes were categorized into 7 groups,including age-related macular degeneration(AMD),polypoidal choroidal vasculopathy(PCV),idiopathic choroidal neovascularization(CNV),proliferative diabetic retinopathy(PDR),diabetic macular edema(DME),macular edema secondary to branch(BVOME)and central(CVOME)retinal vein occlusion.IOP was measured in all patients using rebound tonometer at 7 preset time points perioperatively.Additionally,based on the administered medication,the eyes were classified into three treatment groups,including dexamethasone intravitreal implant(IVO),intravitreal conbercept(IVC),and intravitreal ranibizumab(IVR).To compare IOP values at various time points across groups,we employed one-way ANOVA,independent sample t-test or χ^(2) test and multivariate logistic regression analysis.RESULTS:Peak IOP values across all groups were observed at 40s,and 5min after intravitreal injection.Statistical differences in IOP were detected at the 5min among the 7 indication groups(F=2.50,P=0.029).When examing the impact of medications,the IVO group exhibited lower average IOP values at both 40s and 5min compared to the IVC and IVR groups(P<0.001;P=0.007).The IOP values at 40s and 5min were significantly higher in BVOME and CVOME group compared to non-retinal vein occlusionsecondary macular edema(RVOME)group(P<0.001).Multivariate logistic regression analysis further confirmed that IOP measurement at 40s was significantly higher in CVOME group than in non-RVOME group(OR=1.64,95%CI:1.09-2.47;P=0.018).CONCLUSION:Needle size plays a crucial role in the transient changes of IOP following intravitreal injection.Before administering intravitreal injection to patients with central retinal vein occlusion,it is essential to exclude any underlysing causes of increased IOP.

Bifurcations for counterintuitive post-inhibitory rebound spike related to absence epilepsy and Parkinson disease

Seizures are caused by increased neuronal firing activity resulting from reduced inhibitory effect and enhancement of inhibitory modulation to suppress this activity is used as a therapeutic tool.However,recent experiments have shown a counterintuitive phenomenon that inhibitory modulation does not suppress but elicit post-inhibitory rebound(PIR)spike along with seizure to challenge the therapeutic tool.The nonlinear mechanism to avoid the PIR spike can present theoretical guidance to seizure treatment.This paper focuses on identifying credible bifurcations that underlie PIR spike by modulating multiple parameters in multiple theoretical models.The study identifies a codimension-2 bifurcation called saddle-node homoclinic orbit(SNHOB),which is an intersection between saddle node bifurcation on invariant cycle(SNIC)and other two bifurcations.PIR spike cannot be evoked for the SNIC far from the SNHOBbut induced for the SNIC close to the SNHOB,which extends the bifurcation condition for PIR spike from the well-known Hopf to SNIC.Especially,in a thalamic neuron model,increases of conductance of T-type Ca^(2+)(TC a)channel induce SNIC bifurcation approaching to the SNHOB to elicit PIR spikes,closely matching experimental results of the absence seizure or Parkinson diseases.Such results imply that,when inhibition is employed to relieve absence seizure and Parkinson diseases related to PIR spike,modulating SNIC to get far from the SNHOBto avoid PIR spike is the principle.The study also addresses the complex roles of TCacurrent and comprehensive relationships between PIR spike and nonlinear conceptions such as bifurcation types and shapes of threshold curve.

Vertical deformation before and after the 2022 Menyuan Ms6.9 earthquake and analysis of earthquake precursors

This study analyzed the vertical deformation before and after the 2022 Menyuan Ms6.9 earthquake in Qinghai Province,China,using leveling profiles across faults measured from Minle County in Gansu Province to Menyuan County in Qinghai Province.Our results suggest the following:(1)The amplitude of regional vertical differential motion near the Sunna-Qilian and Lenglongling faults within the Qilian Shan increased before the 2022 Menyuan earthquake.It was accompanied by the emergence of high gradient deformation zones.Deformation at the Tongziba cross-fault leveling site near the Sunan-Qilian fault was considerable.In contrast,deformation at the Daliang cross-fault leveling site near the stepover region(adjacent to the epicenter)between the Lenglongling and Tuolaishan faults was minor.After 2018,vertical deformation at the Tongziba site notably accelerated,while that at the Daliang site was insignificant.(2)After the 2022 Menyuan earthquake,140—150 mm of subsidence deformation occurred near the Daliang site,while the Tongziba site did not experience significant deformation.(3)Vertical deformation before and after the 2022 Menyuan earthquake conforms with the elastic-rebound theory,and the evolution of pre-earthquake deformation was consistent with the strike-slip fault deformation pattern at different seismogenic stages,i.e.,the relative motion near the locked fault in the late seismogenic stage gradually weakened.The characteristics of strain accumulation and release derived from the vertical deformation before and after the Menyuan MS6.9 earthquake help understand the deformation process of earthquake preparation and earthquake precursors.

Eff ect of post-rewarming fever after targeted temperature management in cardiac arrest patients: a systematic review and meta-analysis

BACKGROUND:Targeted temperature management(TTM),as a therapeutic temperature control strategy for cardiac arrest(CA),is recommended by guidelines.However,the relationship between postrewarming fever(PRF)and the prognosis of CA patients is unclear.Therefore,we aim to summarize the studies regarding the infl uence of PRF on patients with CA.METHODS:EMBASE,PubMed,and Cochrane Central databases were searched from inception to March 13,2022.Randomized clinical trials(RCTs)and cohort studies on PRF in CA patients were included.According to the heterogeneity,the meta-analysis was performed using a random eff ects model or fi xed eff ects model to calculate the pooled odds ratios(ORs)and corresponding 95%confi dence intervals(CIs).The outcome data were unfavorable neurological outcome and mortality.RESULTS:The meta-analysis included 11 observational studies involving 3,246 patients.The results of the meta-analysis show that PRF(body temperature>38.0℃)has no eff ect on the neurological outcome of CA patients(OR 0.71,95%CI 0.43–1.17,I282%)and has a signifi cant relationship with lower mortality(OR 0.63;95%CI 0.49–0.80,I239%).However,PRF with a stricter defi nition(body temperature>38.5℃)was associated with worse neurological outcome(OR 1.44,95%CI 1.08–1.92,I245%)and higher mortality(OR 1.71,95%CI 1.25–2.35,I247%).CONCLUSION:This study suggests that PRF>38.0℃ may not affect the neurological outcome and have a lower mortality in CA patients who completed TTM.However,PRF>38.5℃ is a potential prognostic factor for worse outcomes in CA patients.

Changes of spring wind erosion based on wind erosion climate factor in the black soil region of Northeast China

The dry and windy climate and low ground cover in spring in the black soil region of Northeast China make the soil strongly affected by wind erosion,which seriously threatens the food security and ecological security of this region.In this paper,based on the daily observation data of 124 meteorological stations in study area from 1961 to 2020,seasonal and monthly wind erosion climate factor(C)in spring(March to May)were calculated by using the method proposed by the Food and Agriculture Organization of the United Nations(FAO),the wind erosion characterization in spring were systematically analyzed based on C by various statistical analysis methods.The results showed that in the past 60 years,spring wind erosion climate factor(CSp)and monthly C of the whole region and each province(region)all showed highly significant decreasing trend,but they began to show rebounded trend in the middle or late 2000s.CSp of the study area showed a significant upward trend since 2008 with an increase of 4.59(10a)^(-1).The main contributors to this upward trend are the changes of C in March and in April.For the four provinces(regions),CSp in Heilongjiang,Jilin,Liaoning and eastern Inner Mongolia all showed rebounded since 2008,2011,2008 and 2009,respectively.The rebounded trend of CSp in eastern Inner Mongolia was the most obvious with a tendency rate of 11.27(10a)^(-1),and its mutation occurred after 1984.The rebound trend of CSp in Heilongjiang Province takes the second place,with a trend rate of 4.72(10a)^(-1),but there’s no obvious time mutation characteristics.The spatial characteristics of CSpand monthly C are similar,showing decreasing characteristics centered on the typical black soil belt of Northeast China.Compared with 1961-1990,in the period from 1991 to 2020,the proportion of high value areas(CSp>35,monthly C>10)has decreased to varying degrees,while the proportion of low value areas(CSp≤10,monthly C≤4)has increased.The trends of seasonal and monthly C in 82.2%~87.7%of the stations show significant decreases at 95%confidence level.CSp is closely related to wind speed at 2m height,temperature difference,minimum temperature and precipitation in the same period,of which the correlation between CSp and wind speed is the strongest,indicating that the main control factor for CSp in the study area is wind speed,but the impact of the change of temperature and precipitation on CSp cannot be ignored.

Compressive Strength of Basic Magnesium Sulfate Cement Coral Aggregate Concrete(MCAC)on Non-Destructive Testing

Basic magnesium sulfate cement coral aggregate concrete(MCAC)is a new type of concrete consisting of basic magnesium sulfate cement,coarse coral aggregate,coral reef sand and seawater.The rebound hammer(RH),the ultrasonic pulse velocity(UPV)and the compressive strength(fcu)tests of 14 sets of cube specimens of the MCAC after 28 d of aging were conducted.The impact of the content and length of sisal fiber on the relationship between the fcu-RH and the fcu-UPV was determined.A mathematical model was established to predict the strength of the MCAC using the UPV,RH,and comprehensive UPV/RH methods and to obtain the curves of test strength.The applicability of the test strength curves of ordinary portland concrete(OPC),light-weight aggregate concrete(LAC),and coral aggregate concrete(CAC)to MCAC was assessed.The results showed that the test strength curves of OPC,LAC and CAC were inappropriate to determine the strength of MCAC using non-destructive method.The relative standard error of the curves of test strength of the RH method and the comprehensive method met the specifications,whereas that of the UPV method did not.

Chinese textile and garment exports rebounded in March

According to data released by the General Ad­ministration of Customs on April 13th,China's textile and garment exports stopped falling and rebounded in March,which was more than that in February this year and the same period last year,and the overall export stabilized.

Level set method for numerical simulation of a cavitation bubble,its growth, collapse and rebound near a rigid wall

A level set method of non-uniform grids is used to simulate the whole evolution of a cavitation bubble, including its growth, collapse and rebound near a rigid wall. Single-phase Navier-Stokes equation in the liquid region is solved by MAC projection algorithm combined with second-order ENO scheme for the advection terms. The moving inter-face is captured by the level set function, and the interface velocity is resolved by ＂one-side＂ velocity extension from the liquid region to the bubble region, complementing the second-order weighted least squares method across the interface and projection inside bubble. The use of non-uniform grid overcomes the difficulty caused by the large computational domain and very small bubble size. The computation is very stable without suffering from large flow-field gradients, and the results are in good agreements with other studies. The bubble interface kinematics, dynamics and its effect on the wall are highlighted, which shows that the code can effectively capture the ＂shock wave＂-like pressure and velocity at jet impact, toroidal bubble, and complicated pressure structure with peak, plateau and valley in the later stage of bubble oscillating.

Influence of tectonic uplift-erosion on formation pressure

The formation of abnormally low-pressure hydrocarbon reservoirs in petroliferous basins has a close relationship with tectonic uplift and the consequent erosion. In order to understand abnormally low-pressure reservoirs and to provide a scientific basis for exploration and development, we established, through numerical simulation and theoretical analysis, a set of equations for the formation pressure in a closed system influenced by uplift-erosion, discussed the relationship between the genesis of abnormal pressure and uplift-erosion, and put forward the concept of balance pressure （P b ）. The results showed that abnormally high pressure coefficient may form when the current formation pressure was higher than P b , and abnormally low pressure may form when the current formation pressure was lower than P b . In the Santanghu Basin, the current formation pressure of abnormally low pressure reservoirs is lower than P b , so tectonic uplift-erosion leads to the decrease of the pressure coefficient. There is a positive correlation between the pressure drop caused by the decrease of fluid temperature and the rebound of rock porosity and strata erosion. Calculation results indicated that the reservoir pressure of Jurassic strata in the Santanghu Basin was decreased by 11.6-17.1 MPa due to tectonic uplift-erosion during the Late Yanshanian period.

Impact of corneal parameters on intraocular pressure measurements in different tonometry methods

AIM: To evaluate the impact of central corneal thickness(CCT) and corneal curvature on intraocular pressure(IOP) measurements performed by three different tonometers. METHODS: IOP in 132 healthy eyes of 66 participants was measured using three different tonometry techniques: Goldmann applanation tonometer(GAT), Pascal dynamic contour tonometer(DCT), and ICare rebound tonometer(RT). CCT and corneal curvature were assessed. RESULTS: In healthy eyes, DCT presents significantly higher values of IOP than GAT(17.34±3.69 and 15.27±4.06 mm Hg, P<0.0001). RT measurements are significantly lower than GAT(13.56±4.33 mm Hg, P<0.0001). Compared with GAT, DCT presented on average 2.51 mm Hg higher values in eyes with CCT<600 μm and 0.99 mm Hg higher results in eyes with CCT≥600 μm. The RT results were lower on average by 1.61 and 1.95 mm Hg than those obtained by GAT, respectively. Positive correlations between CCT in eyes with CCT<600 μm were detected for all IOP measurement techniques, whereas a similar relationship was not observed in eyes with thicker corneas. A correlation between IOP values and keratometry in the group with CCT<600 μm was not detected with any of the tonometry methods. In thicker corneas, a positive correlation was found for GAT and mean keratometry values(R=0.369, P=0.005). CONCLUSION: The same method should always be chosen for routine IOP control, and measurements obtained by different methods cannot be compared. All analysed tonometry methods are dependent on CCT;thus, CCT should be taken into consideration for both diagnostics and monitoring.

The Testing Strength Curves of Lightweight Aggregate Concrete by Rebound Method and Ultrasonic-rebound Combined Method

The strength curves of lightweight aggregate concrete （LWAC） were tested based on detecting LWAC with density of 1 400-1 900 kg/m3 and LWAC with strength grade of LC15-LC50 by rebound method and ultrasonic-rebound combined method.The results show that the common measured strength curves tested by above two methods can not satisfy the required accuracy of LWAC strength test.In addition,specified compressive strength curves of testing LWAC by rebound method and ultrasonic-rebound combined method are obtained,respectively.

Characterization of Surface Hardness and Microstructure of High Performance Concrete

The relationship between compressive strength obtained by universal testing machine and rebound value obtained by the hammer of high performance concrete was systematically investigated at the macro level. And a model of high performance concrete strength curve was established from them. At the micro level, the microstructure, hydration products and pore structure of concrete surface were analyzed by scanning electron microscopy（SEM）, comprehensive thermal analysis（TG-DSC） and mercury intrusion porosimetry（MIP）, respectively. The effect of carbonation on surface strength was also investigated. The results showed that the concrete surface hardness layer grew rapidly at early stage and then stabilized at last with ongoing curing age; the rebound value and compressive strength of concrete with slag were higher than those of concrete with the same content of fly ash. In addition, the strength curve obtained by the least square method can satisfy the local standard requirements with an average relative error of 8.9% and a relative standard deviation of 11.3%. When the carbonation depth was 6 mm, the compressive strength calculated by national uniform strength curve was 25 PMa higher than that by high performance concrete.

Numerical study on maximum rebound ratio in blasting wave propagation along radian direction normal to joints

In the process of 2-D compressional wave propagation in a rock mass with multiple parallel joints along the radian direction normal to the joints, the maximum possible wave amplitude corresponding to the points between the two adjacent joints in the joint set is controlled by superposition of the multiple transmitted and the reflected waves, measured by the maximum rebound ratio. Parametric studies on the maximum rebound ratio along the radian direction normal to the joints were performed in universal distinct element code. The results show that the maximum rebound ratio is influenced by three factors, i.e., the normalized normal stiffness of joints, the ratio of joint spacing to wavelength and the joint from which the wave rebounds. The relationship between the maximum rebound ratio and the influence factors is generalized into five charts. Those charts can be used as the prediction model for estimating the maximum rebound ratio.

Anisotropy effect on strengths of metamorphic rocks

This paper aims to study the effect of anisotropy on strengths of several metamorphic rocks of southern(Cine) submassif of Menderes metamorphic massif in southwest Turkey. Four different metamorphic rocks including foliated phyllite, schist, gneiss and marble(calcschist) were selected and examined.Discontinuity surveys were made along lines for each rock and evaluated with DIPS program. L-type Schmidt hammer was applied in the directions parallel and perpendicular to foliation during the field study. Several hand samples and rock blocks were collected during the field study for measurements of dry and saturated densities, dry and saturated unit weights and porosity, and for petrographic analysis and strength determination in laboratory. L-and N-type Schmidt hammers were applied in the directions perpendicular(anisotropy angle of 0°) and parallel(anisotropy angle of 90) to the foliation on selected blocks of phyllite, schist, gneiss and marble(calcschist). The phyllite and schist have higher porosity and lower density values than the other rocks. However, coarse crystalline gneiss and marble(calcschist) have higher rebound values and strengths, and they are classified as strong-very strong rocks. Generally, the rebound values in the direction perpendicular to the foliation are slightly higher than that in the direction parallel to foliation. Rebound values of N-type Schmidt hammer are higher than the L-type values except for phyllite. Sometimes, the rebound values of laboratory and field applications gave different results. This may result from variable local conditions such as minerals differentiation,discontinuities, water content, weathering degree and thickness of foliated structure.

EFFECTS OF DESENSITIZATION AND REBOUND TO ADENOSINE ON ACTION POTENTIAL AND CONTRACTILITY IN ATRIAL CELLS IN GUINEA-PIGS

Objective To investigate the effects of desensitization and rebound to adenosine(Ado) on action potential duration(APD) and contractility in guinea-pig atrial cells. Methods Electrical activity was recorded using standard intracellular microelectrode technique and contractility was recorded using. We studied the effects of adenosine on the action potential and desensitization of contractility and rebound of contractility. Results The results showed that action potential duration were shortened by 1,10, 100μ mol·L -1Ado, the ratio of shortened APD was ( 9.58± 1.40)%,(13.80±2.26)%,(24.80±3.19)%, respectively. 1 μ mol·L -1Ado had no desensitization ( P >0.05), but the time of desensitization of 10μ mol·L -1 Ado and 100μ mol·L -1 Ado was 1 minute( P <0.05) and 5 minutes( P < 0.05), respectively. The desensitization of contractility of 10?μ mol·L -1 Ado was obvious in atrial cells, the decrease of contractility of 10?μ mol·L -1 Ado was obvious in atrial cells, the decrease of contractility was changed from (31.4± 16.04)%(2 minutes) to (50.60±15.87)% (4 minutes), compared with control. After washing out Ado, contractility was shown to rebound, the ratio of increase of contractility by 1,10,100 μ mol·L -1 Ado was (12.38±7.50)%,(19.00± 8.14)% and (27.60±13.44)%, respectively. Conclusion Ado can abbreviate APD in atrial cells. The desensitization of Ado on APD is characterized by concentration-dependent and time-dependent in atrial cells, and the desensitization of contractility of Ado is obvious and contractility was shown to rebound after washing out Ado.

Dynamics and rebound behavior analysis of flexible tethered satellite system in deployment and station-keeping phases

The tether deployment of a tethered satellite system involves the consideration of complex dynamic properties of the tether,such as large deformation,slack,and even rebound,and therefore,the dynamic modelling of the tether is necessary for performing a dynamic analysis of the system.For a variablelength tether element,the absolute nodal coordinate formulation(ANCF)in the framework of the arbitrary Lagrange-Euler(ALE)description was used to develop a precise dynamic model of a tethered satellite.The model considered the gravitational gradient force and Coriolis force in the orbital coordinate frame,and it was validated through numerical simulation.In the presence of dynamic constraints,a deployment velocity of the tether was obtained by an optimal procedure.In the simulation,rebound behavior of the tethered satellite system was observed when the ANCF-ALE model was employed.Notably,the rebound behavior cannot be predicted by the traditional dumbbell model.Furthermore,an improved optimal deployment velocity was developed.Simulation results indicated that the rebound phenomenon was eliminated,and smooth deployment as well as a stable state of the station-keeping process were achieved.Additionally,the swing amplitude in the station-keeping phase decreased when a deployment strategy based on the improved optimal deployment velocity was used.

Extension Model of Crustal Uplifting in Western Shandong

Block faults, as the -dominant tectonic framwork of western Shandong, were formed by the linked extensional fault system through two extensional movements during the Meso-Cenozoic. Both of the extensional movements experienced the same evloutional process: first, the upper crust was pulled apart to form faults; then the Tai-Lu-Yi (Taishan-Lushan-Yishan) fault block occurring in the footwall of the extensional fault was uplifted, which induced the shallow-level detachment movement along the early Precambrian and Palaeozoic unconformity; the ' branching' fault in the upper part of the deep-level detachment layer propagated. As the shallow detachment moved towards the north and the deep one towards the south, the Tai-Lu-Yi fault block acted as the common footwall of both the southern and northern detachment systems. The Tai-Lu-Yi fault block rebounded and uplifted as the overlying material was pulled apart to cause an unloading. Sialic material of the mid-crust below the deep detachment flowed to and accumulated in the free space below the rebounding uplifted body and thickened the body; whereas the mid-crust thinned under the graben systems. The rebounding uplifted body cooled, and then the graben system was occluded, which resulted in the crust-mantle isostatic adjustment and asthenospheric convection. As a result of the two extensional movements, the uplifted central Shandong block with the Tai-Lu-Yi area as the core stands highly above the surrounding plain characterized by graben systems. The present Mount Taishan forms the climax of the uplift.

Rebound effect and its decomposition-an analysis based on energy types in China

Rebound effect derived from energy efficiency improvement has been widely invested.However,most of studies focus on the rebound effect of the energy composite level and neither distinguish nor compare different energy types.We compare the differences in energy saving and energy rebound between primary and secondary energy sources,and further decompose the rebound effect into production rebound part and final demand component.To do so,we add a module for rebound into a comparative state China-CGE model.We design and test two simulation scenarios using the model.In Scenario 1,all production sectors' energy efficiency of using primary energy increases by 5%.In Scenario 2,all production sectors' energy efficiency of using secondary energy increases by 5%.The results show that Scenario 2 leads to more GDP growth and more energy saving.Our scenarios show rebound effects range between 9.6% and 27.9%,and in general are higher when energy efficiency of using primary energy sources is improved.Our decomposition analysis shows that improving energy efficiency in production sectors would stimulates energy use of final demand.Indeed,the consumption side has significant contribution to rebound in secondary energy use,especially in crude oil and gas.This study reveals that improving efficiency of using secondary energy is better than improving that of primary energy,both in terms of economic impact and energy rebound.And complementary policies that prevent energy services prices from falling too much can be adopted to reduce rebound.Controlling residential energy use could also be effective in reducing rebound,this has particular implication to economies in which residential energy consumption are far from saturation.

Intraocular pressure measurement over soft contact lens by rebound tonometer: a comparative study

AIM: To evaluate the intraocular pressure(IOP)measurements by Icare rebound tonometer over a contact lens in comparison with Goldmann applanation tonometry(GAT). METHODS: Fifty patients using contact lens were included in this study. One of the eyes of the patients was selected randomly and their IOP were measured by rebound tonometer with and without contact lens(RTCL,RT respectively) and by GAT, as well as their central corneal thickness(CCT) by optical pachymeter. The results of both methods were compared by correlation analysis, general linear method repeated measure and Bland-Altman analysis.RESULTS: Mean IOP values measured by RTCL, RT and GAT were 15.68 ±3.7, 14.50 ±3.4 and 14.16 ±2.8(P 【0.001), respectively. Mean IOP by RTCL was significantly higher than the measurements implemented by RT and GAT(P 【0.001), while there was no difference between the measurements by GAT and RT(P =0.629). There was a good level of positive correlation between GAT and RTCL as well as RT(r =0.786 P 【0.001, r =0.833 P 【0.001, respectively). We have observed that CCT increase did not show any correlation with the differences of the measurements between RTCL and RT(P =0.329), RTCL and GAT(P =0.07) as well as RT and GAT(P =0.189) in linear regression model.CONCLUSION: The average of the measurements over contact lens by rebound tonometer was found to be higher than what was measured by GAT. Although this difference is statistically significant, it may be clinically negligible in the normal population.

Experimental study on prediction model for maximum rebound ratio

The proposed prediction model for estimating the maximum rebound ratio was applied to a field explosion test, Mandai test in Singapore. The estimated possible maximum peak particle velocities(PPVs) were compared with the field records. Three of the four available field-recorded PPVs lie exactly below the estimated possible maximum values as expected, while the fourth available field-recorded PPV lies close to and a bit higher than the estimated maximum possible PPV. The comparison results show that the predicted PPVs from the proposed prediction model for the maximum rebound ratio match the field-recorded PPVs better than those from two empirical formulae. The very good agreement between the estimated and field-recorded values validates the proposed prediction model for estimating PPV in a rock mass with a set of joints due to application of a two dimensional compressional wave at the boundary of a tunnel or a borehole.