Simultaneous estimation of indirect and interaction effects using structural equation models

Interaction effects are usually modeled by means of moderated regression analysis. Structural equation models with non-linear constraints make it possible to estimate interaction effects while correcting for measurement error. From the various specifications, J��reskog and Yang's (1996, 1998), likely the most parsimonious, has been chosen and further simplified. Up to now, only direct effects have been specified, thus wasting much of the capability of the structural equation approach. This paper presents and discusses an extension of J��reskog and Yang's specification that can handle direct, indirect and interaction effects simultaneously. The model is illustrated by a study of the effects of an interactive style of use of budgets on both company innovation and performance

Analysis of creep strain during tensile fatigue of cortical bone

During fatigue tests of cortical bone specimens, at the unload portion of the cycle (zero stress) non-zero strains occur and progressively accumulate as the test progresses. This non-zero strain is hypothesised to be mostly, if not entirely, describable as creep. This work examines the rate of accumulation of this strain and quantifies its stress dependency. A published relationship determined from creep tests of cortical bone (Journal of Biomechanics 21 (1988) 623) is combined with knowledge of the stress history during fatigue testing to derive an expression for the amount of creep strain in fatigue tests. Fatigue tests on 31 bone samples from four individuals showed strong correlations between creep strain rate and both stress and ���normalised stress��� (��/E) during tensile fatigue testing (0���T). Combined results were good (r2=0.78) and differences between the various individuals, in particular, vanished when effects were examined against normalised stress values. Constants of the regression showed equivalence to constants derived in creep tests. The universality of the results, with respect to four different individuals of both sexes, shows great promise for use in computational models of fatigue in bone structures.

Development of a method fon non-destructive testing of fruits using scanning laser vibrometry (SLV)

Quality control on fruits requires reliable methods, able to assess with reasonable accuracy and possibly in a non-destructive way their physical and chemical characteristics. More specifically, a decreased firmness indicates the presence of damage or defects in the fruit or else that the fruit has exceeded its ���best before date���, becoming unsuitable for consumption. In high-value exotic fruits, such as mangoes, where firmness cannot be easily measured from a simple observation of texture, colour changes and unevenness of fruits surface, the use of non-destructive techniques is highly recommendable. In particular, the application of Laser vibrometry, based on the Doppler effect, a non-contact technique sensitive to differences in displacements inferior to the nanometre, appears ideal for a possible on-line control on food. Previous results indicated that a phase shift can be in a repeatable way associated with the presence of damage on the fruit, whilst a decreased firmness results in significant differences in the displacement of the fruits under the same excitation signal. In this work, frequency ranges for quality control via the application of a sound chirp are suggested, based on the measurement of the signal coherence. The variations of the average vibration spectrum of a grid of points, or of point-by-point signal velocity allows the go-no go recognition of ���firm��� and ���over-ripe��� fruits, with notable success in the particular case of mangoes. The future exploitation of this work will include the application of this method to allow on-line control during conveyor belt distribution of fruits.

Medidas de deslocamento e vibra����es atrav��s de imagens de c��meras digitais

P��s-gradua����o em Engenharia Mec��nica - FEIS

The effects of heat-moisture treatment on avocado starch granules: thermoanalytical and structural analysis

Coordena����o de Aperfei��oamento de Pessoal de N��vel Superior (CAPES)

Valutazione dell'accuratezza e della precisione di un algoritmo di correlazione digitale di volumi applicato a vertebre naturali e trattate

La Digital Volume Correlation (DVC) �� una tecnica di misura a tutto campo, non invasiva, che permette di misurare spostamenti e deformazioni all���interno della struttura ossea in esame. Mediante la comparazione d���immagini con provino scarico e con provino carico, ottenute attraverso sistemi di tomografia computerizzata, si pu�� ottenere la mappa degli spostamenti per ogni direzione e la mappa di deformazione per ogni componente di deformazione. L���obiettivo di questo lavoro di tesi �� la validazione della DVC, attraverso la determinazione dell���errore sistematico (accuratezza) e dell���errore casuale (precisione), in modo da poter valutare il livello di affidabilit�� della strumentazione. La valutazione si effettua su provini di vertebre di maiale, aumentate e non, sia a livello d���organo, sia a livello di tessuto. The Digital Volume Correlation (DVC) is a full field and contact less measurement technique that allowed estimating displacement and strain inside bone specimen. Images of the unloaded and loaded specimen were obtained from micro-CT and compared in order to obtain the displacement map and, differentiating, the strain map. The aim of this work is the validation of the approach, estimating the lack of accuracy (systematic error) and the lack of precision (random error) on different kinds of porcine vertebra, augmented and not, analysing the specimen on tissue level and on organ level.

Failure mechanism of reinforced concrete structural walls with and without confinement

This paper presents the results of cyclic loading tests on two large-scale reinforced concrete structural walls that were conducted at Purdue University. One of the walls had confinement reinforcement meeting ACI-318-11 requirements while the other wall did not have any confinement reinforcement. The walls were tested as part of a larger study aimed at indentifying parameters affecting failure modes observed to limit the drift capacity of structural walls in Chile during the Maule Earthquake of 2010. These failure modes include out-of-plane buckling (of the wall rather tan individual reinforcing bars), compression failure, and bond failure. This paper discusses the effects of confinement on failure mode. Distributions of unit strain and curvature obtained with a dense array of non-contact coordinate-tracking targets are also presented.

Fatiga en CFRP: Caracterizaci��n y M��todo ��ptico para la Estimaci��n del Da��o

El desarrollo de nuevas estructuras aeroespaciales optimizadas, utilizan materiales compuestos, para los componentes cr��ticos y subsistemas, principalmente pol��meros reforzados con fibra de carbono (CFRP). Un conocimiento profundo del estado de da��o por fatiga de estructuras de CFRP avanzado, es esencial para predecir la vida residual y optimizar los intervalos de inspecci��n estructural, reparaciones y/o sustituci��n de componentes. Las t��cnicas actuales se basan principalmente en la medici��n de cargas estructurales a lo largo de la vida ��til de la estructura mediante galgas extensom��tricas el��ctricas. Con esos datos, se estima la vida a fatiga utilizando modelos de acumulaci��n de da��o. En la presente tesis, se eval��a la metodolog��a convencional para la estimaci��n de la vida a fatiga de un CFRP aeron��utico. Esta metodolog��a est�� basada en la regla de acumulaci��n de da��o lineal de Palmgren-Miner, y es aplicada para determinar la vida a fatiga de estructuras sometidas a cargas de amplitud variable. Se ha realizado una campa��a de ensayos con cargas de amplitud constante para caracterizar un CFRP aeron��utico a fatiga, obteniendo las curvas cl��sicas S-N, en diferentes relaciones de esfuerzo. Se determinaron los diagramas de vida constante, (CLD), tambi��n conocidos como diagramas de Goodman, utilizando redes neuronales artificiales debido a la ausencia de modelos coherentes para materiales compuestos. Se ha caracterizado la degradaci��n de la rigidez debido al da��o por fatiga. Se ha ensayado un segundo grupo de probetas con secuencias estandarizadas de cargas de amplitud variable, para obtener la vida a fatiga y la degradaci��n de rigidez en condiciones realistas. Las cargas aplicadas son representativas de misiones de aviones de combate (Falstaff), y de aviones de transporte (Twist). La vida a fatiga de las probetas cicladas con cargas de amplitud variable, se compar�� con el ��ndice de da��o te��rico calculado en base a la regla de acumulaci��n de da��o lineal convencional. Los resultados obtenidos muestran predicciones no conservativas. Esta tesis tambi��n presenta el estudio y desarrollo, de una nueva t��cnica de no contacto para evaluar el estado de da��o por fatiga de estructuras de CFRP por medio de cambios de los par��metros de rugosidad. La rugosidad superficial se puede medir f��cilmente en campo con m��todos sin contacto, mediante t��cnicas ��pticas tales como speckle y perfil��metros ��pticos. En el presente estudio, se han medido par��metros de rugosidad superficial, y el factor de irregularidad de la superficie, a lo largo de la vida de las probetas cicladas con cargas de amplitud constante y variable, Se ha obtenido una buena tendencia de ajuste al correlacionar la magnitud de la rugosidad y el factor de irregularidad de la superficie con la degradaci��n de la rigidez de las probetas fatigadas. Estos resultados sugieren que los cambios en la rugosidad superficial medida en zonas estrat��gicas de componentes y estructuras hechas de CFRP, podr��an ser indicativas del nivel de da��o interno debido a cargas de fatiga. Los resultados tambi��n sugieren que el m��todo es independiente del tipo de carga de fatiga que ha causado el da��o. Esto ��ltimo hace que esta t��cnica de medici��n sea aplicable como inspecci��n para una amplia gama de estructuras de materiales compuestos, desde tanques presurizados con cargas de amplitud constante, estructuras aeron��uticas como alas y colas de aeronaves cicladas con cargas de amplitud variable, hasta aplicaciones industriales como automoci��n, entre otros. ABSTRACT New optimized aerospace structures use composite materials, mainly carbon fiber reinforced polymer composite (CFRP), for critical components and subsystems. A strong knowledge of the fatigue state of highly advanced (CFRP) structures is essential to predict the residual life and optimize intervals of structural inspection, repairs, and/or replacements. Current techniques are based mostly on measurement of structural loads throughout the service life by electric strain gauge sensors. These sensors are affected by extreme environmental conditions and by fatigue loads in such a way that the sensors and their systems require exhaustive maintenance throughout system life. In the present thesis, the conventional methodology based on linear damage accumulation rules, applied to determine the fatigue life of structures subjected to variable amplitude loads was evaluated for an aeronautical CFRP. A test program with constant amplitude loads has been performed to obtain the classical S-N curves at different stress ratios. Constant life diagrams, CLDs, where determined by means of Artificial Neural Networks due to the absence of consistent models for composites. The stiffness degradation due to fatigue damage has been characterized for coupons under cyclic tensile loads. A second group of coupons have been tested until failure with a standardized sequence of variable amplitude loads, representative of missions for combat aircraft (Falstaff), and representative of commercial flights (Twist), to obtain the fatigue life and the stiffness degradation under realistic conditions. The fatigue life of the coupons cycled with variable amplitude loads were compared to the theoretical damage index calculated based on the conventional linear damage accumulation rule. The obtained results show non-conservative predictions. This thesis also presents the evaluation of a new non-contact technique to evaluate the fatigue damage state of CFRP structures by means of measuring roughness parameters to evaluate changes in the surface topography. Surface roughness can be measured easily on field with non-contact methods by optical techniques such as speckle and optical perfilometers. In the present study, surface roughness parameters, and the surface irregularity factor, have been measured along the life of the coupons cycled with constant and variable amplitude loads of different magnitude. A good agreement has been obtained when correlating the magnitude of the roughness and the surface irregularity factor with the stiffness degradation. These results suggest that the changes on the surface roughness measured in strategic zones of components and structures made of CFRP, could be indicative of the level of internal damage due to fatigue loads. The results also suggest that the method is independent of the type of fatigue load that have caused the damage. It makes this measurement technique applicable for a wide range of inspections of composite materials structures, from pressurized tanks with constant amplitude loads, to variable amplitude loaded aeronautical structures like wings and empennages, up to automotive and other industrial applications.

Targetless image-based method for measuring displacements and strains on concrete surfaces with a consumer camera

Measurement of concrete strain through non-invasive methods is of great importance in civil engineering and structural analysis. Traditional methods use laser speckle and high quality cameras that may result too expensive for many applications. Here we present a method for measuring concrete deformations with a standard reflex camera and image processing for tracking objects in the concretes surface. Two different approaches are presented here. In the first one, on-purpose objects are drawn on the surface, while on the second one we track small defects on the surface due to air bubbles in the hardening process. The method has been tested on a concrete sample under several loading/unloading cycles. A stop-motion sequence of the process has been captured and analyzed. Results have been successfully compared with the values given by a strain gauge. Accuracy of our methods in tracking objects is below 8 ��m, in the order of more expensive commercial devices.

Quantum trajectories for the realistic measurement of a solid-state charge qubit

We present a new model for the continuous measurement of a coupled quantum dot charge qubit. We model the effects of a realistic measurement, namely adding noise to, and filtering, the current through the detector. This is achieved by embedding the detector in an equivalent circuit for measurement. Our aim is to describe the evolution of the qubit state conditioned on the macroscopic output of the external circuit. We achieve this by generalizing a recently developed quantum trajectory theory for realistic photodetectors [P. Warszawski, H. M. Wiseman, and H. Mabuchi, Phys. Rev. A 65, 023802 (2002)] to treat solid-state detectors. This yields stochastic equations whose (numerical) solutions are the realistic quantum trajectories of the conditioned qubit state. We derive our general theory in the context of a low transparency quantum point contact. Areas of application for our theory and its relation to previous work are discussed.

Accommodation and intraocular pressure

The relationship between accommodation and intraocular pressure (lOP) has not been addressed as a research question for over 20 years, when measurement of both of these parameters was less advanced than today. Hence the central aim of this thesis was to evaluate the effects of accommodation on lOP. The instrument of choice throughout this thesis was the Pulsair EasyEye non-contact tonometer (NCT) due principally to its slim-line design which allowed the measurement of lOP in one eye and simultaneous stimulation of accommodation in the other eye. A second reason for using the Pulsair EasyEye NCT was that through collaboration with the manufacturers (Keeler, UK) the instrument's operational technology was made accessible. Hence, the principle components underpinning non-contact lOP measures of 0.1mmHg resolution (an order of magnitude greater than other methods) were made available. The relationship between the pressure-output and corneal response has been termed the pressure-response relationship, aspects of which have been shown to be related to ocular biometric parameters. Further, analysis of the components of the pressure-response relationship together with high-speed photography of the cornea during tonometry has enhanced our understanding of the derivation of an lOP measure with the Pulsair EasyEye NCT. The NCT samples the corneal response to the pressure pulse over a 19 ms cycle photoelectronically, but computes the subject's lOP using the data collected in the first 2.34 ms. The relatively instantaneous nature of the lOP measurement renders the measures susceptible to variations in the steady-state lOP caused by the respiratory and cardiac cycles. As such, the variance associated with these cycles was minimised by synchronising the lOP measures with the cardiac trace and maintaining a constant pace respiratory cycle at 15 breathes/minute. It is apparent that synchronising the lOP measures with the peak, middle or trough of the cardiac trace significantly reduced the spread of consecutive measures. Of the 3 locations investigated, synchronisation with the middle location demonstrated the least variance (coeflicient of variation = 9.1%) and a strong correlation (r = 0.90, p = <0.001) with lOP values obtained with Goldmann contact tonometry (n = 50). Accordingly lOP measures synchronised with the middle location of the cardiac cycle were taken in the RE while the LE fixated low (L; zero D), intermediate (I; 1.50 D) and high (H; 4 D) accommodation targets, Quasi-continuous measures of accommodation responses were obtained during the lOP measurement period using the portable infrared Grand Seiko FR-5000 autorefractor. The lOP reduced between L and I accommodative levels by approximately 0.61 mmHg (p <0.00 I). No significant reduction in IOP between L and H accommodation levels was elicited (p = 0.65) (n = 40). The relationship between accommodation and lOP was characterised by substantial inter-subject variations. Myopes demonstrated a tendency to show a reduction in IOP with accommodation which was significant only with I accommodation levels when measured with the NCT (r = 0.50, p = 0.01). However, the relationship between myopia and lOP change with accommodation reached significance for both I (r = 0.61, p= 0.003) and H (r = 0.531, p= 0.0 1) accommodation levels when measured with the Ocular blood Flow Analyser (OBFA). Investigation of the effects of accommodation on the parameters measured by the OBFA demonstrated that with H accommodation levels the pulse amplitude (PA) and pulse rate (PR) responses differed between myopes and emmetropes (PA: p = 0.03; PR: p = 0.004). As thc axial length increased there was a tendency for the pulsatile ocular blood flow (POBF) to reduce with accommodation, which was significant only with H accommodation levels (r = 0.38, p = 0.02). It is proposed that emmetropes arc able to regulate the POBF responses to changes in ocular perfusion pressure caused by changes in lOP with I (r = 0.77, p <0.001) and H (r = 0.73, p = 0.001) accommodation levels. However, thc relationship between lOP and POBF changes in the myopes was not correlated for both I (r = 0.33, p = 0.20) and H (r = 0.05, p = 0.85) accommodation levels. The thesis presents new data on the relationships between accommodation, lOP and parameters of the OBFA,: and provides evidence for possible lOP and choroidal blood flow regulatory mechanisms. Further the data highlight possible deficits in the vascular regulation of the myopic eye during accommodation, which may play a putative role in the aetiology of myopia development.

Fibre Bragg grating strain sensors

The fabrication of in-fibre Bragg gratings (FBGs) and their application as sensors is reported. The strain and temperature characteristic results for a number of chirped and uniform gratings written into three different host fibres are presented. The static and dynamic temperature response of a commercially available temperature compensated grating is reported. A five sensor wavelength division multiplexed fibre Bragg grating strain measurement system with an interrogation rate of 25 Hz and resolution of 10 was constructed. The results from this system are presented. A novel chirped FBG interrogation method was implemented in both the 1.3 and 1.5 m telecommunication windows. Several single and dual strain sensor systems, employing this method, were constructed and the results obtained from each are reported and discussed. These systems are particularly suitable for the measurement of large strain. The results from a system measuring up to 12 m and with a potential measurement range of 30 m are reported. This technique is also shown to give an obtainable resolution of 20 over a measurement range of 5 000 for a dual sensor system. These systems are simple, robust, passive and easy to implement. They offer low cost, high speed and, in the case of multiple sensors, truly simultaneous interrogation. These advantages make this technique ideal for strain sensing in SMART structures. Systems based on this method have been installed in the masts of four superyachts. A system, based on this technique, is currently being developed for the measurement of acoustic waves in carbon composite panels. The results from an alternative method for interrogating uniform FBG sensors are also discussed. Interrogation of the gratings was facilitated by a specifically written asymmetric grating which had a 15 nm long linearly sloped spectral edge. This technique was employed to interrogate a single sensor over a measurement range of 6 m and two sensors over a range of 4.5 me. The results obtained indicated achievable resolutions of 47 and 38 respectively.

Impact of soft contact lens edge design and mid-peripheral lens shape on the epithelium and its indentation with lens mobility

Purpose. To evaluate the influence of soft contact lens midperipheral shape profile and edge design on the apparent epithelial thickness and indentation of the ocular surface with lens movement. Methods. Four soft contact lens designs comprising of two different plano midperipheral shape profiles and two edge designs (chiseled and knife edge) of silicone-hydrogel material were examined in 26 subjects aged 24.7 �� 4.6 years, each worn bilaterally in randomized order. Lens movement was imaged enface on insertion, at 2 and 4 hours with a high-speed, high-resolution camera simultaneous to the cross-section of the edge of the contact lens interaction with the ocular surface captured using optical coherence tomography (OCT) nasally, temporally, and inferiorly. Optical imaging distortions were individually corrected for by imaging the apparent distortion of a glass slide surface by the removed lens. Results. Apparent epithelial thickness varied with edge position (P < 0.001). When distortion was corrected for, epithelial indentation decreased with time after insertion (P = 0.010), changed after a blink (P < 0.001), and varied with position on the lens edge (P < 0.001), with the latter being affected by midperipheral lens shape profile and edge design. Horizontal and vertical lens movement did not change with time postinsertion. Vertical motion was affected by midperipheral lens shape profile (P < 0.001) and edge design (P < 0.001). Lens movement was associated with physiologic epithelium thickness for lens midperipheral shape profile and edge designs. Conclusions. Dynamic OCT coupled with high-resolution video demonstrated that soft contact lens movement and image-corrected ocular surface indentation were influenced by both lens edge design and midperipheral lens shape profiles. �� 2013 The Association for Research in Vision and Ophthalmology, Inc.

Simultaneous measurement of strain and curvature using superstructure fibre Bragg gratings

We report the first demonstration of the simultaneous measurement of strain and curvature, with temperature compensation, using a single superstructure fibre Bragg grating (SFBG). The SFBG exhibits the properties of both the fibre Bragg grating (FBG) and the long period fibre grating (LPG) such that its spectral response facilitates strain measurement from the wavelength shift of the FBG-like characteristic, and independent measurement of curvature from the LPG-like mode-splitting characteristic. The dependence of the LPG mode-splitting on the mode order has also been investigated and utilised for the measurement of very small curvatures.

Effets des contraintes psychosociales au travail sur la d��tresse psychologique et les absences m��dicalement certifi��es pour probl��mes de sant�� mentale: une ��tude prospective de 5 ans

Contexte : Les effets cumul��s des contraintes psychosociales du mod��le d��s��quilibre efforts-reconnaissance (DER) sur la sant�� mentale sont peu connus. Aussi, peu d�����tudes ont ��valu�� les effets du DER sur des indicateurs objectifs de probl��mes de sant�� mentale (PSM). Enfin, aucune ��tude prospective ant��rieure n���a ��valu�� l���effet combin�� des contraintes psychosociales du DER et du mod��le demande-latitude (DL) et sur les PSM m��dicalement certifi��s. La pr��sente th��se vise �� combler ces limites. Objectifs : 1) Mesurer l���effet de l���exposition cumul��e au d��s��quilibre efforts-reconnaissance sur la pr��valence de la d��tresse psychologique sur une p��riode de cinq ans; 2) Mesurer l���effet du d��s��quilibre efforts-reconnaissance sur l���incidence des absences m��dicalement certifi��es pour PSM sur une p��riode de cinq ans; 3) ��valuer l���effet ind��pendant et l���effet combin�� des contraintes psychosociales des mod��les Demande-Latitude et D��s��quilibre Efforts-Reconnaissance sur l���incidence des absences m��dicalement certifi��es pour PSM sur une p��riode de cinq ans. M��thodes : La cohorte ��tait constitu��e de plus de 2000 hommes et femmes occupant des emplois de cols blancs. La collecte des donn��es a ��t�� r��alis��e �� trois reprises avec une moyenne de suivi de cinq ans. �� chaque temps, les contraintes psychosociales et la d��tresse psychologique ont ��t�� mesur��es �� l���aide d���instruments valid��s. Les absences m��dicalement certifi��es pour PSM ont ��t�� r��colt��es �� partir des fichiers administratifs des employeurs. Les PSM ont ��t�� mod��lis��s �� l���aide des r��gressions log-binomiale et de Cox. Les analyses ont ��t�� r��alis��es s��par��ment chez les hommes et les femmes, en ajustant pour les principaux facteurs de confusion. R��sultats : Chez les hommes et les femmes, une exposition chronique au DER sur trois ans ��tait associ��e �� une pr��valence plus ��lev��e de la d��tresse psychologique. Les effets observ��s �� trois ans ont persist�� �� cinq ans chez les hommes (Rapport de pr��valence (RP)=1,91 (1,20���3,04)) et les femmes (RP=2,48 (1,97���3,11)). Ces effets ��taient de plus grande amplitude que ceux observ��s en utilisant l���exposition initiale �� l���entr��e dans l�����tude (de +0,30 �� +0,94). Par ailleurs, les hommes et les femmes expos��s au DER pr��sentaient un risque plus ��lev�� d���absences m��dicalement certifi��es pour PSM (Risque relatif (RR)=1,38 (1,08���1,76)), compar��s aux travailleurs non-expos��s. La faible reconnaissance au travail ��tait associ��e �� un risque important d���absences pour PSM chez les hommes (RR=3,04 (1,46���6,33)) mais pas chez les femmes (RR=1,24 (0,90���1,72)). Chez les femmes uniquement, un effet ind��pendant du �� job strain �� (RR=1,50 (1,12���2,07)) et du DER (RR=1,34 (0,98���1,84)), ainsi qu���un effet de l���exposition combin��e au �� job strain �� (demande psychologique ��lev��e et faible latitude d��cisionnelle) et au DER (RR=1,97 (1,40���2,78)) sur le risque d���absences m��dicalement certifi��es pour PSM ont ��galement ��t�� observ��s. Conclusion : Les r��sultats de cette th��se supportent l���effet d��l��t��re de l���exposition au DER sur la pr��valence de la d��tresse psychologique et sur le risque d���absences m��dicalement certifi��es pour PSM chez les hommes et les femmes. Chez les hommes et les femmes, l���exposition cumul��e au DER ��tait associ��e �� une pr��valence ��lev��e de la d��tresse psychologique �� trois ans et �� cinq ans. De plus, les contraintes psychosociales du DER ont ��t�� associ��es aux absences m��dicalement certifi��s pour PSM. Chez les femmes particuli��rement, un effet combin�� du �� job strain �� et du DER ��tait associ�� �� un risque plus ��lev�� d���absences m��dicalement certifi��es pour PSM, que l���exposition �� un seul des deux facteurs. Ces r��sultats sugg��rent que la r��duction des contraintes psychosociales au travail pourrait contribuer �� r��duire l���incidence des PSM, incluant les absences m��dicalement certifi��es pour PSM.