Physical Rotation Research Articles

What Does Physical Rotation Reveal About Mental Rotation?

In a classic psychological science experiment, Shepard and Metzler (1971) discovered that the time participants took to judge whether two rotated abstract block figures were identical increased monotonically with the figures’ relative angular disparity. They posited that participants rotate mental images to achieve a match and that mental rotation recruits motor processes. This interpretation has become central in the literature, but until now, surprisingly few researchers have compared mental and physical rotation. We had participants rotate virtual Shepard and Metzler figures mentally and physically; response time, accuracy, and real-time rotation data were collected. Results suggest that mental and physical rotation processes overlap and also reveal novel conclusions about physical rotation that have implications for mental rotation. Notably, participants did not rotate figures to achieve a match, but rather until they reached an off-axis canonical difference, and rotational strategies markedly differed for judgments of whether the figures were the same or different.

Virtual couch shift (VCS): accounting for patient translation and rotation by online IMRT re-optimization

When delivering conventional intensity modulated radiotherapy (IMRT), discrepancies between the pre-treatment CT/MRI/PET based patient geometry and the daily patient geometry are minimized by performing couch translations and/or small rotations. However, full compensation of, in particular, rotations is usually not possible. In this paper, we introduce an online ‘virtual couch shift (VCS)’: we translate and/or rotate the pre-treatment dose distribution to compensate for the changes in patient anatomy and generate a new plan which delivers the transformed dose distribution automatically. We show for a phantom and a cervical cancer patient case that VCS accounts for both translations and large rotations equally well in terms of DVH results and 2%/2 mm γ analyses and when the various aspects of the clinical workflow can be implemented successfully, VCS can potentially outperform physical couch translations and/or rotations. This work is performed in the context of our hybrid 1.5 T MRI linear accelerator, which can provide translations and rotations but also deformations of the anatomy. The VCS is the first step toward compensating all of these anatomical changes by online re-optimization of the IMRT dose distribution.

Characterization and Recognition of Bistatic Polarimetric Mechanisms

Our final objective is the automatic recognition of targets from full-polarimetric bistatic synthetic aperture radar images. To this end, the theories of Huynen and Cameron are generalized to bistatic radar scattering, and their respective characteristic parameters are compared. We have then studied first how to characterize and compare bistatic mechanisms free from physical rotations and second how to build “coherent” reference memories. Two algorithms are proposed and tested.

The puzzle of combination frequencies found in heat‐driven pulsators

AbstractSearching for combinations in the frequency spectra of variable stars is a commonly used method within the asteroseismological community, as harmonics and linear combinations of individual frequencies are expected to appear not only by chance, but also as a characteristic signature linked to different physical phenomena, e.g., nonlinear oscillations, binarity, and rotation. Furthermore it is very important to identify independent frequencies for modelling purposes. We show that using high precision data sets delivered by recent space missions, the distinction between combinations having a real physical meaning and spurious combinations which only appear by chance gets more and more difficult. We demonstrate how careful one should be with the interpretation of such combination frequencies by presenting the statistical distributions derived from artificial data sets. Based on comparisons to observations, we find that, despite the high statistical probability of finding combinations in random data sets (having similar properties to the ones of real stars), there is a significant difference in the number of the lowest order combinations between stars with and starts without real combination frequencies. This way, a search for frequency combinations is very useful when interpreted properly, and when results are compared to simulations (© 2012 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)

Egocentric updating of remote locations

The study examined whether people update remote spatial locations in unfamiliar environments during physical movement. Participants learned a layout of objects from one perspective and carried out perspective-taking trials after physically rotating to a new perspective in either the same room as learning or in an adjacent room. Prior to rotation in the adjacent room participants were instructed to visualize the objects as being around them. Responses to perspective-taking trials involved either pointing or verbal labeling. In both testing environments, participants pointed more efficiently from imagined perspectives aligned with either the initial learning perspective or their current facing orientation than from a novel imagined perspective; this indicates that they had updated the encoded spatial relations during the physical rotation and treated remote objects as immediate. Differences in performance among perspectives were less pronounced for verbal labeling in both environments, suggesting that this response mode is more flexibly used from imagined perspectives.

Transverse magnetic exchange springs in a DyFe2/YFe2superlattice

Using a history-dependent method, it is possible to prepare magnetic superlattices, consisting of alternating hard and soft layers, in transverse exchange spring states. The procedure, which involves both physical rotation and magnetization routines, is illustrated using a (110)-oriented [DyFe${}_{2}$(60 \AA{})/YFe${}_{2}$(240 \AA{})]${}_{15}$ multilayer film. In small applied fields, it is shown that the magnetic response of a transverse magnetic exchange spring is reversible. However, in fields of up to 14 T, the Dy moments are pulled up out of their local in-plane [00$\overline{1}$] minimum into an out-of-plane [100] (or equivalent [010]) axis. The reversible transverse exchange spring state is then lost. Thereafter, the magnetic loop is characterized by an irreversible out-of-plane magnetic exchange spring state.

Characteristics of WWTP sludge after drying in greenhouse for agricultural purposes

The sludge generated by sewage treatment which meets regulatory standards can be used in agriculture. With this understanding, the focus of this study is the evaluation of the agricultural characteristics and inorganic substances in excess activated sludge, which was subjected to drying in a greenhouse. The variables (factor) evaluated during the drying process were: type of sludge (digested or not digested), addition of lime to the sludge, and the physical layout and rotation of sludge in the greenhouse. The parameters monitored for this assessment were moisture, volatile solids and pH. The greenhouse cover and sides were made of translucent plastic to allow the penetration of solar radiation and prevent water from entering. A impermeable floor was used. The sludge was generated in sewage treatment plants located in the metropolitan region of Grande Vitória, Espírito Santo, Brazil. The solar drying of wastewater sludge in a greenhouse presented satisfactory results.

Advanced Casing Design With Finite-Element Model of Effective Dogleg Severity, Radial Displacements, and Bending Loads

Summary A purpose-built finite-element model (FEM) is applied to simulate radial displacement of a casing string constrained within an outer wellbore. The FEM represents a fully stiff-string model wherein the casing is approximated by general-beam elements with six degrees of freedom at each node to account for all possible physical displacements and rotations. Results predicted include deflection of the casing centerline from the wellbore centerline, effective dogleg curvature, bending deformation, wall-contact forces, and bending-stress magnification. These results will provide for a more-accurate assessment of well integrity in terms of casing-stress safety factors and centralization before cementing, as well as more accurate prediction of running loads during the drilling phase. In critical-well-casing design, accurate assumptions regarding bending stiffness may be necessary to avoid overly conservative as well as nonconservative analysis. Challenging finite high-pressure/ high-temperature (HP/HT) and extreme-temperature wells are opportunities for increased design efficiency by avoiding overly conservative and costly designs, which can be crucial. Alternatively, design for extreme loads such as overpull loads in long deviated wells may be nonconservative if severe bending stresses are not considered. A realistic case study is presented that demonstrates the possibility to achieve cost efficiency by means of optimized casing design. A case study also is presented in which a nonconservative design may result if severe bending loads are not modeled. The purpose-built FEM code is in many ways preferable to the use of commercial finite-element-analysis (FEA) packages because of the time-consuming effort required to build up the detailed model. In typical casing and tubular-stress design, a soft-string model assumes casing strings are coincident with the wellbore centerline. The known or assumed wellbore curvature is applied directly to the casing string. Any effect of casing-string stiffness and allowable radial displacement within the outer wellbore is ignored. In many cases, this results in an overly conservative analysis. Likewise, the impact of bending-stress magnification is typically ignored, along with the effects of centralizer placement. This may also be nonconservative for critical overpull situations, such as in extended-reach-drilling (ERD) and horizontal wells.

The Complex Algebra of Physical Space: A Framework for Relativity

A complex and, equivalently, hyperbolic extension of the algebra of physical space (APS) is discussed that allows one to distinguish space-time vectors from paravectors of APS, while preserving the natural origin of the Minkowski space-time metric. The CAPS formalism is Lorentz covariant and gives expression to persistent vectors in physical space as time-like planes in space-time. Commuting projectors $${P_{\pm} = \frac{1}{2} (1 \pm h)}$$ project CAPS onto two-sided ideals, one of which is APS. CAPS has the same dimension as the space-time algebra (STA) if both are considered real algebras, and it distinguishes covariant roles of elements, as does STA. Its structure, however, is closer to APS, with a volume element that belongs to the center of the algebra and a simple relation between space-times of opposite signature. Furthermore, CAPS, unlike STA, distinguishes point-like space-time inversion of a Dirac spinor from a physical rotation. To illustrate its use, CAPS is applied to the Dirac equation and to the fundamental symmetry transformations of the equation and Dirac spinors. The physical interpretations of both the equation and the spinor are clarified, and it is seen that the space-time frame $${\{\gamma_{\mu}\}}$$ arises fully from relative vectors and does not imply the existence of an absolute space-time frame.

Object Recognition Can Be Viewpoint Dependent or Invariant – It's Just a Matter of Time and Task

As we move through our environment, we encounter familiar objects from various viewpoints. Despite the ensuing variability of the images projected onto the retina, we have seemingly little difficulty when it comes to recognizing objects we encounter. We can, however, see how the objects are oriented, suggesting that object recognition is to a certain degree dissociable from perception of other object “features” such as orientation. Changes in orientation of objects, particularly inversion, can also affect how we perceive the objects. A particularly illustrative example (shown in Figure ​Figure1)1) is that of the Thatcher illusion (Thompson, 1980), where the grotesque appearance of a face with its inverted eyes and mouth is “hidden” when the whole face is also inverted. The percept itself, therefore, is affected by the change in orientation. In addition, there are also subtle effects of viewpoint changes on object recognition itself. For example, identifying rotated objects is more difficult when they are briefly presented than when viewing time is unlimited (Lawson and Jolicoeur, 2003), and identifying a face is considerably more difficult the face has been inverted (Yin, 1969), as is discrimination between characters “b” and “d,” or “p” and “q” which requires (physical or mental) rotation of the characters to upright, before we can be certain which letter we are looking at (Corballis and McLaren, 1984). Figure 1 Unaltered and “thatcherized” version of Margaret Thatcher's face. The grotesque appearance of the face when its eyes and mouth are inverted is hidden by the inversion of the whole image. Rotating the pictures to upright makes discrimination ... These subtle, yet persistent, effects of viewpoint changes on perception and recognition arise as a consequence of how visual object processing is handled by the brain. Here, I discuss how neural mechanisms underlying visual processing give rise to perception and recognition which can be both viewpoint dependent and viewpoint invariant depending on the timing of those processes, as well as specific task demands or current “perceptual goals” of an individual. To do so, I will firstly explain how temporal dynamics of low-level visual processing may give rise to impaired recognition at short viewing latencies and suggest that this may also relate to effects of viewpoint changes on perceptual experience. I will then discuss how the perceptual goals of an individual determines whether recognition is accomplished in viewpoint invariant or dependent manner with a particular focus on cognitive operations thought to be subserved by ventral and dorsal visual streams, namely object recognition and mental rotation, respectively.

Multi-Dimensional Moving Least Squares Method for Elasticity Problems

The “Multi-dimensional moving least squares method with constraint condition (C-MultiMLS)” is applied to elasticity problems. The physical values, for example, rotations, strains, and curvatures, are defined as the degrees of freedom (DOFs) of the displacement function of a particle by using the C-MultiMLS. In this paper, we use a weak form of the governing equation, that is the C-MultiMLS has been constructed for the test and trial functions of a particle. In this method, the DOFs which we should be finally solved in the simultaneous linear equation is only displacement DOFs, therefore, this method might be suitable also for the large-scale simulations. We discuss the accuracy of this method in elastic bodies through some numerical examples.

Design and Performance of the Transverse Rotating Magnetic Field Steered Arc Source Used in Vacuum Arc Deposition

In this design, the concept of static magnetic field was given up and the idea of controlling the arc discharge by transverse rotating magnetic field (TRMF) was put forward. Based on the principle of RMF generation, the specific scheme and the cohesiveness integral structure design of the TRMF steered arc source were constructed. In the specific design, a bipolar symmetric RMF (N-S) parallel to the cathode surface and homogenously covered the whole cathode was generated by stationary three-phase windings carrying three-phase alternating currents without any visible physical rotation. Through changing the frequency and the amplitude of the exciting current (these two parameters can be adjusted independently), the speed of rotation and the magnetic intensity could be regulated continuously. Experiments about TRMF steered arc source used in vacuum arc deposition (VAD) showed that: the arc voltage increased with not only an increase in the intensity of magnetic field connected with the supplied current but also an increase in the frequency of magnetic field. TRMF could reduce MPs content to a great extent and get a smooth film surface. A high utilization of the target was achieved due to the homogenous arc discharge covered the entire cathode surface. We believe this design is a new-type arc source and it will bring inspiration and great interest in the VAD domain.

Composite spectra: XVII. 12 Comae, a member of the Coma open cluster

AbstractThe components of binary stars offer the potential to examine the predictions of stellar‐evolution theory with particularly tight constraints. Those constraints are further tightened when the binary belongs to a cluster whose properties have been well determined independently. 12 Comae presents both advantages, belonging as it does to the Coma Cluster, Melotte 111. The orbit of 12 Comae has an eccentricity of nearly 0.6 and a period of 13 months. By a process of subtraction we separate the spectra of the component stars, derive a precise double‐lined orbit solution, and by modelling the photometry we extract the individual stellar photometric and physical properties, ages and rotation. By fitting theoretical evolutionary tracks to the positions of the stars in the H‐R diagram we confirm their individual masses, and derive a ZAMS of ∼0.65 Gyr, which accords well with measurements published for the cluster itself. We show that the primary of 12 Comae is an evolving giant of spectral type ∼G7 and mass 2.6 M⊙, while its secondary (whose spectrum could be isolated particularly cleanly) is an A3 dwarf which has a mass of 2.05 M⊙ and has commenced its evolution away from the main sequence. There is evidence that both stars are slightly metal‐weak (–0.25 < [Fe/H] < 0.0), well in keeping with analyses of other members of this cluster (© 2011 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)

Comparison between five commonly used two-dimensional methods of human bite mark overlay production from the dental study casts

The present study was conducted to determine the most accurate bite mark overlay fabrication technique by studying two physical characteristics, i.e., area and rotation of biting edges of anterior teeth of thirty volunteers. The objective of the study was to evaluate the reliability and efficacy of five commonly used methods of human bite mark overlays using two dimensional (2D) digital images of dental study casts as a gold standard, to rank different methods according to statistically based determination of relative accuracy of each method and to determine its feasibility in Forensic science. Overlays were produced from the biting surfaces of six upper and six lower anterior teeth of 30 volunteers using the following five methods: a) hand tracing from study casts, b) hand tracing from wax impressions, c) xerographic method, d) radiopaque impression method and e) 2D computer-based method. Area of the biting edges of the anterior teeth and relative rotation of each anterior tooth were measured and compared. The xerographic method was determined to be the more accurate method with respect to tooth area and rotation. Hand tracing methods, from either wax impressions of teeth or directly from study casts, were determined to be inaccurate and subjective. It is recommended that forensic odontologists discontinue the use of hand tracing overlays in bite mark comparison cases as there is lot of scope for manipulation and observer bias.

Predictive models for dry weight estimation of above and below ground biomass components of Populus deltoides in India: Development and comparative diagnosis

Abstract This article concentrates on development of statistical models for prediction of biomass components (above and below ground) of standing trees of Populus deltoides . Twenty seven trees (three each from age one to nine years) were destructively harvested, separated, sorted, sub-sampled, dried to constant weight at 60 °C and weighted for biomass components (leaf, twig, branch, bole, stump root, lateral root, fine root). Harvesting in a similar manner, was continued annually up to nine years of tree age and thus in all 27 sampled trees were available for analysis and fitting of models. Diameter at breast height (dbh) alone was a very good predictor of dry weight and accordingly the height was not included in the model. Various functions viz (linear, allometric, logistic, gompertz and chapman-richards), were attempted for dry weight estimation. The linear model, though easiest to fit, suffered from the ‘negative estimation problem’, specifically for the lower range of explanatory variate. Of the remaining non-linear models, the allometric model outperformed the others on the basis of validation criterions. The value of R 2 ranged from 0.95 to 0.99, for the allometric models fitted on various biomass components. The proposed models can be used for prediction of component wise dry biomass of P. deltoides for a wide range of dbh values (1–50 cm) at one end and can also help farmers in the choice of economical harvest rather than the traditional physical rotation. In addition, they can be used in carbon sequestration studies, which needs complete biomass estimation.

Synthesis of enantiomerically pure phosphonic analog of natural aspartic acid

Methyl ester of L-serine I was Boc-protected at the NH-group [1], then the obtained (S)-hydroxyaminocarboxylate II was transformed into bromide (R)-III through reaction with triphenylphosphine and trichlorobromomethane in methylene chloride at 70°С. Bromide III was purified by vacuum distillation and brought into the Arbuzov reaction with five-fold excess of triethyl phosphite, the reaction proceeded at 135–140°С over 12 h. After distilling off the volatile reaction product at 0.1 mm Hg at 120°С, the phosphonate IV was obtained, which was purified by column chromatography. Its structure was proved by the Н, С and Р NMR spectroscopy and mass spectrometry. The heating of compound IV with hydrochloric acid affords (R)-(+)-С-phosphonoaspartic acid V. This compound have been earlier obtained by a more complicated method [2]. The physical properties and optical rotation angle coincided with the published data. Methyl (S)-tert-buthoxycarbonylamino-3-hydroxypropionate (II). To a solution of 10.5 g (0.05 mol) of (S)-methyl serinate hydrochloride in 10 ml of THF was added 15 g of triethylamine at 0°С and this mixture was stirred for 30 min. Then 12 g of Boc2O was added, and the reaction mixture was warmed to room temperature, stirred for 6 h, and then refluxed for 3 h. Then it was cooled, poured into the saturated aqueous sodium hydrogen bicarbonate solution, extracted with diethyl ether, and concentrated. Yield 90%, [α]D 18.0 (MeOH, c 5), colorless oil. Н NMR spectrum (CDCl3), δ, ppm: 1.44 s [9H, (CH3)3C], 3.77 s (3H, CH3O), 3.9 m (2H, CH2), 4.38 m (1H, CHN), 5.57 br.s (1H, NH).

Detection of endogenous magnetic nanoparticles with a tunnelling magneto resistance sensor

The magnetotactic bacterium Magnetospirillum sp. has been cultured and the properties of its endogenous magnetic nanoparticles characterized. Electron-microscopic analyses indicate that the endogenous magnetite nanoparticles in Magnetospirillum sp. are coated with a 3-4 nm thick transparent shell, forming a magnetosome. These magnetite nanoparticles had diameters of 50.9+/-13.3 nm, in good agreement with the diameter of 40.6+/-1.2 nm extracted from magnetometry. Each Magnetospirillum sp. bacterium contained chains of 5-25 magnetosomes. Superconducting quantum interference device magnetometry results indicate that the extrinsic superparamagnetic response of the bacterial solution at room temperature can be attributed to the reversal of the magnetization by physical rotation of the nanoparticles. The intrinsic blocking temperature of a sample of freeze-dried bacteria was estimated to be 282+/-13 K. A tunnelling magneto resistance sensor was used to detect the stray fields of endogenous magnetic nanoparticles in static and quasi-dynamic modes. Based on the tunnelling magneto resistance sensor results, the magnetic moment per bacterium was estimated to be approximately 2.6 x 10(-13) emu. The feasibility of this detection method either as a mass-coverage device or as part of an integrated microfluidic circuit for detection and sorting of magnetosome-containing cells was demonstrated.

Simulating magnetic nanoparticle behavior in low-field MRI under transverse rotating fields and imposed fluid flow

In the presence of alternating-sinusoidal or rotating magnetic fields, magnetic nanoparticles will act to realign their magnetic moment with the applied magnetic field. The realignment is characterized by the nanoparticle's time constant, τ . As the magnetic field frequency is increased, the nanoparticle's magnetic moment lags the applied magnetic field at a constant angle for a given frequency, Ω , in rad s −1. Associated with this misalignment is a power dissipation that increases the bulk magnetic fluid's temperature which has been utilized as a method of magnetic nanoparticle hyperthermia, particularly suited for cancer in low-perfusion tissue (e.g., breast) where temperature increases of between 4 and 7 °C above the ambient in vivo temperature cause tumor hyperthermia. This work examines the rise in the magnetic fluid's temperature in the MRI environment which is characterized by a large DC field, B 0. Theoretical analysis and simulation is used to predict the effect of both alternating-sinusoidal and rotating magnetic fields transverse to B 0. Results are presented for the expected temperature increase in small tumors ( ∼ 1 cm radius) over an appropriate range of magnetic fluid concentrations (0.002–0.01 solid volume fraction) and nanoparticle radii (1–10 nm). The results indicate that significant heating can take place, even in low-field MRI systems where magnetic fluid saturation is not significant, with careful the goal of this work is to examine, by means of analysis and simulation, the concept of interactive fluid magnetization using the dynamic behavior of superparamagnetic iron oxide nanoparticle suspensions in the MRI environment. In addition to the usual magnetic fields associated with MRI, a rotating magnetic field is applied transverse to the main B 0 field of the MRI. Additional or modified magnetic fields have been previously proposed for hyperthermia and targeted drug delivery within MRI. Analytical predictions and numerical simulations of the transverse rotating magnetic field in the presence of B 0 are investigated to demonstrate the effect of Ω , the rotating field frequency, and the magnetic field amplitude on the fluid suspension magnetization. The transverse magnetization due to the rotating transverse field shows strong dependence on the characteristic time constant of the fluid suspension, τ . The analysis shows that as the rotating field frequency increases so that Ω τ approaches unity, the transverse fluid magnetization vector is significantly non-aligned with the applied rotating field and the magnetization's magnitude is a strong function of the field frequency. In this frequency range, the fluid's transverse magnetization is controlled by the applied field which is determined by the operator. The phenomenon, which is due to the physical rotation of the magnetic nanoparticles in the suspension, is demonstrated analytically when the nanoparticles are present in high concentrations (1–3% solid volume fractions) more typical of hyperthermia rather than in clinical imaging applications, and in low MRI field strengths (such as open MRI systems), where the magnetic nanoparticles are not magnetically saturated. The effect of imposed Poiseuille flow in a planar channel geometry and changing nanoparticle concentration is examined. The work represents the first known attempt to analyze the dynamic behavior of magnetic nanoparticles in the MRI environment including the effects of the magnetic nanoparticle spin-velocity. It is shown that the magnitude of the transverse magnetization is a strong function of the rotating transverse field frequency. Interactive fluid magnetization effects are predicted due to non-uniform fluid magnetization in planar Poiseuille flow with high nanoparticle concentrations.

Estimation of Detection Thresholds for Redirected Walking Techniques

In immersive virtual environments (IVEs), users can control their virtual viewpoint by moving their tracked head and walking through the real world. Usually, movements in the real world are mapped one-to-one to virtual camera motions. With redirection techniques, the virtual camera is manipulated by applying gains to user motion so that the virtual world moves differently than the real world. Thus, users can walk through large-scale IVEs while physically remaining in a reasonably small workspace. In psychophysical experiments with a two-alternative forced-choice task, we have quantified how much humans can unknowingly be redirected on physical paths that are different from the visually perceived paths. We tested 12 subjects in three different experiments: (E1) discrimination between virtual and physical rotations, (E2) discrimination between virtual and physical straightforward movements, and (E3) discrimination of path curvature. In experiment E1, subjects performed rotations with different gains, and then had to choose whether the visually perceived rotation was smaller or greater than the physical rotation. In experiment E2, subjects chose whether the physical walk was shorter or longer than the visually perceived scaled travel distance. In experiment E3, subjects estimate the path curvature when walking a curved path in the real world while the visual display shows a straight path in the virtual world. Our results show that users can be turned physically about 49 percent more or 20 percent less than the perceived virtual rotation, distances can be downscaled by 14 percent and upscaled by 26 percent, and users can be redirected on a circular arc with a radius greater than 22 m while they believe that they are walking straight.

A PROPOSAL SOLUTION FOR INTERFERENCE INTER-OPERATORS

With deregulation of telecom sector (law 24/96) in our country (Morocco), many operators of cellular network appear. Among the operators technology that operate, we find GSM9800 and CDMA900 that are used by two different operators. It turns out from the measurements of indicator of quality of service that the performance of GSM900 is degraded, and the major cause is the interference created by CDM800 which cannot be neglected. In this paper, we adopt a new approach in order to make GSM900 and CDMA800 operate in harmony. This method is based on a physical optimization of antenna systems and could be understood as a physical symmetry rotation in the space of parameters such that tilt and Azmit control the system. It independently reduces the interference effects on the distance between the base stations. Moreover, it allows us to improve client service without using hard installations and inexpensive technologies.