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At least 19 recordsLinked to original sources
PubMed2003

Amotosalen: Allogeneic Cellular Immunotherapies system, INTERCEPT Plasma System, INTERCEPT Platelet System, S 59.

Adis CommentsCerus Corporation is developing a variety of pathogen-inactivation systems, based on its Helinx technology. Three of the systems include amotosalen [S 59] as the inactivation compound. Amotosalen is a light-activated, DNA-, RNA-crosslinking psoralen compound, which is used to neutralise pathogens. The systems that utilise amotosalen are called the INTERCEPT Platelet System, the INTERCEPT Plasma System and the Allogeneic Cellular Immunotherapies (ACIT) system. The INTERCEPT Platelet System and INTERCEPT Plasma System are two of the systems that make up Cerus' INTERCEPT Blood Systems. The other system is the INTERCEPT Red Blood Cell System, which contains S 303 as the inactivation compound rather than amotosalen. Cerus' Helinx technology is able to prevent replication of DNA or RNA that is present in pathogens but not in the blood components being treated (e.g. platelets and plasma). When added to the blood components, the inactivation agent (in this case amotosalen) crosses the membrane or cell wall of the pathogen. When activated by light, amotosalen binds to the nucleic acid of the pathogen and prevents replication. This process prevents infection. INTERCEPT Platelet System: Cerus developed its INTERCEPT Platelet System, in collaboration with Baxter Healthcare, for use in blood centres. Platelets are an essential component of the coagulation process and may be required by patients undergoing surgery, cancer chemotherapy, transplantation or with bleeding disorders. The system is made up of an illuminator device, a compound absorption device and a processing kit containing amotosalen. In October 2002, the two companies announced that CE Mark approval had been received for the illuminator device for the INTERCEPT trade mark Blood System. Application of this technology to platelets is the first to be approved. As it is a new technology, the system is currently undergoing process validation in accordance with European Blood Bank GMP requirements. This validation process is currently being conducted in Denmark, France, Germany, Sweden and the UK. Marketing approval applications for the INTERCEPT Platelet System have also been submitted in Australia and Canada. In addition, the regulatory submission process has begun in the US. A phase III trial (EuroSPRITE) has been conducted in 103 patients in Europe with pooled random donor platelets. The platelets were collected using the buffy coat process. Another two 20-patient clinical trials have also been conducted in Europe, as well as a 40-patient trial using platelets collected by an apheresis collection system. Cerus has also conducted a phase III trial (SPRINT) in the US. The trial was conducted in 671 patients and used platelets collected by Baxter's apheresis collection system. INTERCEPT Plasma System: Cerus is also developing the INTERCEPT Plasma System in collaboration with Baxter Healthcare. The system also combines amotosalen, an illumination device and a compound absorption device. The two companies are currently preparing regulatory applications for the INTERCEPT Plasma System for the US. This application will be followed by a submission for CE Mark designation in Europe. Patients undergoing surgery, or transplantation, or with bleeding disorders, may require transfusions of plasma, often to control bleeding. The type of plasma is stored in frozen form and is called fresh frozen plasma (FFP). The INTERCEPT Plasma System is currently in phase IIIc development in the US. Patient enrolment in the trial is still ongoing. The trial is comparing INTERCEPT trade mark Plasma System treated versus untreated FFP in 30 patients with thrombotic thrombocytopenic purpura. Allogeneic Cellular Immunotherapies system: Cerus is also investigating the potential of its Helinx technology to improve the outcome of bone marrow transplantation procedures (used to treat leukaemia and lymphoma) through the treatmatment for many forms of leukaemia and is most effective when the donor is very closely matched to the patient for the major human leucocyte antigen (HLA) groups. As part of the transplant procedure, patients receive donor T cells to improve engraftment of the bone marrow transplant and strengthen the patient's immune system. However, donor T cells expose the patient to a high risk of contracting graft-versus-host disease (GVHD) caused by the proliferation of donor T cells, which attack the patient's healthy tissue. GVHD has a high mortality rate. Cerus' ACIT system has been developed to decrease the stringency of matching donors to patients and to inhibit the ability of donor T cells to cause GVHD. Light-activated amotosalen binds and permanently crosslinks DNA, preventing replication and thus stopping proliferation of donor T cells. Phase I development is currently being conducted in this area in the US using amotosalen as the neutralising agent. Cerus completed a phase I study investigating the safety and tolerability of its ACIT system in 2001. The study was conducted in patients receiving closely matched allogeneic bone marrow transplants for leukaemia. The company is currently collaborating with the National Marrow Donor Program in order to conduct further clinical studies in patients receiving bone marrow transplants from unmatched donors. Cerus has development, manufacturing and marketing agreements with Baxter covering the INTERCEPT Blood Systems, which includes the INTERCEPT Platelet system, the INTERCEPT Plasma System, and the INTERCEPT Red Blood Cell System. Under the terms of the agreements the two companies usually share the very early development activities. Cerus then conducts preclinical and clinical trials, while Baxter is responsible for the development of the systems disposables and devices. Following commercialisation Cerus will supply amotosalen and Baxter will supply the other components of the system and market, sell and distribute the system In January 2001, Cereus announced that it has entered into a collaborative agreement with the Pharmaceutical Division of Kirin Brewery in Japan to develop and market products for stem cell transplantation based on Cerus' proprietary Helinx technology. Under terms of the agreement, Cerus and Kirin will jointly develop the products. Cerus has received an initial license fee of US dollar 1 million. In addition it may receive up to US dollar 11 million in future payments upon achievement of development milestones. Kirin will also fund all development expenses for the Asia-Pacific region and a portion of Cerus' development activities aimed at obtaining product approval in the US. Kirin will market the products in the Asia-Pacific region, including Japan, China, Korea and Australia, and Cerus will receive a specified share of product revenues. Cerus will retain marketing rights in the rest of the world, including the US and Europe.

Anti-Infective Agents↗
PubMed1996

Rainfall interception and drop size-development and calibration of the two-layer stochastic interception model.

This paper reviews the development of the stochastic interception model from the original, single-layer, drop-size-dependent model to the two-layer model that recognizes that vegetation canopies are wetted through both the primary impact of raindrops to the top layer of the canopy and secondary impacts from drops falling from the vegetation to lower layers of the canopy. It is shown that drop volumes of primary raindrops can be calculated from the Marshall-Palmer distribution and drop volumes of secondary drops can be estimated from disdrometer measurements of the characteristic volume appropriate to the particular vegetation species. It is recognized that, in addition to the volume-dependent stochastic wetting effect, there is also another drop-size-dependent wetting effect that is related to the kinetic energy of the raindrops, which reduces the maximum storage that can be achieved on the canopy. The predicted wetting functions for canopies of different density are described and compared with observations made with the use of a rainfall simulator. It is also shown that the species-dependent model parameters can be determined from measurements made with the rainfall simulator. The improved performance of the model compared with conventional interception models is demonstrated for a tropical forest in Sri Lanka. Application of the two-layer model may explain why interception losses from coniferous, fine-leaved forests in the temperate, low-intensity rainfall climate of the uplands of the U.K. are among the highest in the world, whereas interception losses from tropical broad leaved forest in high-intensity rainfall climates of the tropics are among the lowest.

Journal Article↗
PubMed1994

Palatally impacted canines: aetiology of impaction and the scope for interception. Report of cases outside the guidelines for interception.

Patients with palatally impacted canines have an increased incidence of missing or anomalous lateral incisors adjacent to the impacted canines. Their arches are often uncrowded and this, in part, is linked to the increased incidence of missing or anomalous lateral incisors. Other teeth are also more frequently missing. The present guidelines for the relief of palatally impacted canines by extraction of the deciduous canine require that the patient is aged between 10-13 years and that normal space conditions are present. Two successful case reports are presented which were outside the recommended guidelines. The technique of relieving a palatal impaction by extraction of the deciduous canine has wide application.

Adolescent↗
PubMed1996

Intercepting real and path-guided apparent motion targets.

Human subjects were instructed to intercept with a cursor real and apparent motion targets presented on a computer screen. Targets traveled counterclockwise (CCW) in a circle at one of five angular velocities (180, 300, 420, 480 and 540 deg/s), either smoothly (real motion) or in path-guided apparent motion. Subjects operated a computer mouse and were instructed to intercept targets at the 12 o'clock position; there were no constraints on when to initiate the response, which was a movement from the center of the screen towards and past 12 o'clock. We found the following: (a) for both motion conditions and all target velocities, subjects were late in intercepting the target, especially at higher target velocities; (b) for both motion conditions, the directional variability of the response increased as a linear function of the target velocity; (c) the directional variability of the response was systematically higher for the apparent than the real motion condition; there was no significant interaction between target velocity and target motion type; (d) the response time did not vary significantly with velocity, but was consistently longer for apparent than real motion targets; (e) the movement time was very similar for different target velocities; and (f) the moment of initiation of the interception movement was delayed appreciably at higher target velocities, relative to that dictated for perfect interception at a given target velocity. This delay was greater for the apparent motion target. These results demonstrated the following: (a) for both target motion conditions, interception was not fully predictive but lagged the target in spite of the constant target velocity and the unconstrained time allowed for initiating the interception movement; (b) subjects can intercept an apparent motion target but, compared with real motion, the performance is somewhat degraded overall; (c) the similarities in performance between the two target motion conditions, and the fact that target velocity influenced performance in a similar fashion, suggest that the motor system can access the visual information provided by the moving target; and (d) since movement time was similar for different target velocities, the strategy for interception relied on controlling the moment of initiation of the interception movement. This was successful for low target velocities but became unsuccessful at higher target velocities.

Adult↗
PubMed2000

Interceptive orthodontics in the real world of community dentistry.

OBJECTIVE: To test the applicability and effectiveness of interceptive orthodontics in a community field trial. DESIGN: Prospective screening for suitable malocclusions, implementation of treatment and analysis of outcomes 12 months later. SETTING: Community dentistry in urban and rural areas of Northern Ireland, 1996-98. SUBJECTS AND METHODS: The initial sample consisted of 2002 children (1014 boys, 988 girls) who were screened in routine community dental inspections. One thousand and sixty (523 aged 9 years, 537 aged 11 years) were domiciled in the urban area of greater Belfast and 942 (479 aged 9 years, 463 aged 11 years) in the rural area of Enniskillen and Omagh, Co. Tyrone. INTERVENTIONS: Interceptive orthodontic treatment. OUTCOME MEASURES: Dental health component of the Index of Orthodontic Treatment Need (IOTN) and specially devised local indices of treatment outcomes. RESULTS: With the use of an interception gauge, orthodontic screening was included in the community dental inspections without difficulty. Thirty-three per cent of children were in need of interceptive treatment. Only 20% of those in need both attended for recall and underwent treatment. Compliance was better in the rural area but the need, with particular reference to extraction of carious first molars, was greater in the urban area. The numbers of children in IOTN grades 4 and 5 fell from 69% at the beginning of the study to 42% at the end. The outcome judged by local indices was 94% in the range of complete success to minimal improvement with only 2% showing deterioration. CONCLUSIONS: One in three children screened in community dental inspections at age 9 and 11 years would benefit from interceptive orthodontics. Parents and children seem reluctant to accept offers of interceptive orthodontics and to having the treatment carried out. Among those complying fully, the interceptive measures are very successful. Not only does community interceptive orthodontics improve the condition being treated but also reduces the need for further treatment.

Chi-Square Distribution↗
PubMed2003

Interception of real and apparent motion targets: psychophysics in humans and monkeys.

Human subjects and monkeys intercepted real (RM) and apparent (AM) moving targets that traveled through a low contrast circular path. The subjects intercepted the targets at 6 o'clock by applying a net force pulse on a semi-isometric joystick which controlled a cursor on the screen. Eight target speeds (180-560 degrees/s) were used. The starting points of the moving target were systematically placed around the circle in order to determine the effect of the target travel time and velocity on the decision to initiate the interception movement and on the interception accuracy. It was found that the probability of interception in the first revolution varied as a function of the target travel time, which followed an S-shaped psychometric curve. The minimum processing time (MPT) was defined as the target travel that corresponded to a 75% probability of interception in the first revolution on the psychometric curve. The MPT decreased slightly as a function of target speed and was larger in AM than RM. In addition, the interception accuracy increased when the target travel time was above the MPT, and the angular error was smaller in RM than in AM. Finally, the interception movement was initiated at different target locations and time-to-contacts, depending on the target speed and the motion condition. Interestingly, similar findings were observed in human subjects and monkeys. These results suggest that the neural mechanisms engaged in extracting the visual motion information and in the implementation of the response are more efficient during RM than AM, and that such mechanisms need less processing time when the target is moving faster.

Adult↗
PubMed2003

Optical acceleration cancellation: a viable interception strategy?

Interception of fly balls requires active locomotion toward the point where catching can take place; as a result, the visual information guiding interception is affected by the catcher's own movement. The only interception theory currently available for a catcher standing in the plane of motion of the ball is Optical Acceleration Cancellation (OAC); in this strategy, the pseudo-optical variable "optical acceleration" (OA), if nonzero, specifies how the catcher should adjust his current velocity. We formulate a precise implementation of OAC where the catcher strives to maintain OA zero at all times and analyze its implications in terms of the catcher's interception behavior for different ball trajectories under air-friction-free, low-friction, and friction-dominated conditions. We conclude that the point in the ball trajectory where first visual contact (FVC) takes place determines to a large extent the ensuing interception behavior of the catcher. Conventional trajectories (FVC slightly above eye level, ball coming toward the catcher) result in fast acceleration to a constant velocity and successful interception. Trajectories with FVC below eye level typically result in unsatisfactory behavior of the catcher, who runs away from rather than toward the point of interception. In addition, ball trajectories are identified for which the OA equals zero even though the catcher is not on an interception course.

Acceleration↗
PubMed2006

The effects of capture spiral composition and orb-web orientation on prey interception.

Cribellar prey capture threads found in primitive, horizontal orb-webs reflect more light, including ultraviolet wavelengths, than viscous threads found in more derived, vertical orb-webs. Low web visibility and vertical orientation are each thought to increase prey interception and may represent key innovations that contributed to the greater diversity of modern, araneoid orb-weaving spiders. This study compares prey interception rates of cribellate orb-webs constructed by Uloborus glomosus (Uloboridae) with viscous orb-webs constructed by Leucauge venusta (Tetragnathidae) and Micrathena gracilis (Araneidae). We placed sectors of cribellar and viscous threads side by side in frames that were oriented either horizontally or vertically. The webs of both U. glomosus and L. venusta intercepted more prey when vertically oriented. In each orientation L. venusta webs intercepted more insects than did U. glomosus. Although this is consistent with the greater visibility of cribellar threads, the more closely spaced capture spirals of L. venusta may have contributed to this difference. Micrathena gracilis webs intercepted more prey than did U. glomosus webs, although web orientation did not affect the performance of this araneoid species. The stickier and more closely spaced capture spirals of M. gracilis may have enhanced the interception rates of this species and accounted for the greater number of smaller dipterans retained in its webs. The tendency for these slow, weak flight insects to be blown into both horizontal and vertical webs may account for similar interception rates of horizontal and vertical M. gracilis webs. These observations support the enhanced prey interception of vertically oriented orb-webs, but offer only qualified support for the contributions of lower visibility viscous capture threads.

Animals↗
PubMed1998

Nonrandom sequence of slope-intercept estimates in longitudinal gompertzian analysis suggests biological relevance.

The significance of intersections in age-specific mortality rate distributions could be attributed to a fundamental statistical relationship between estimates of slope and intercept. A strong negative correlation between estimates of slope and intercept is often observed in simple linear regression problems. The net result is that the family of lines generated by repetitive estimates of slope and intercept in a static experimental situation will tend to intersect at a common point. This statistical relationship between slope and intercept, however, should be random with respect to the time-ordered sequence of slope and intercept estimates. Annual paired slope and intercept estimates derived using the method of longitudinal Gompertzian analysis of age-specific mortality rates for men and women in the United States from 1900 to 1988 were analyzed to determine if they varied randomly. The probability that the observed sequence in these annual paired slope-intercept estimates was random is less than 10(-50) for both men and women. This finding essentially excludes the possibility that intersections in age-specific mortality rate distributions reflect a fundamental statistical relationship between slope and intercept and further suggests biological relevance for the method of longitudinal Gompertzian analysis.

Female↗
PubMed2001

Motor cortical activity during interception of moving targets.

The single-unit activity of 831 cells was recorded in the arm area of the motor cortex of two monkeys while the monkeys intercepted a moving visual stimulus (interception task) or remained immobile during presentation of the same moving stimulus (no-go task). The moving target traveled on an oblique path from either lower corner of a screen toward the vertical meridian, and its movement time (0.5, 1.0, or 1.5 sec) and velocity profile (accelerating, decelerating, or constant velocity) were pseudorandomly varied. The moving target had to be intercepted within 130 msec of target arrival at an interception point. By comparing motor cortical activity at the single-neuron and population levels between the interception and no-go tasks, we tested whether information about parameters of moving target is represented in the primary motor cortex to generate appropriate motor responses. A substantial number of neurons displayed modulation of their activity during the no-go task, and this activity was often affected by the stimulus parameters. These results suggest a role of motor cortex in specifying the timing of movement initiation based on information about target motion. In addition, there was a lack of systematic relation between the onset times of neural activity in the interception and no-go tasks, suggesting that processing of information concerning target motion and generation of hand movement occurs in parallel. Finally, the activity in the most motor cortical neurons was modulated according to an estimate of the time-to-target interception, raising the possibility that time-to-interception may be coded in the motor cortical activity.

Animals↗
PubMed2006

[Estimation of rainfall interception by broad-leaved Korean pine forest in Changbai Mountains].

Rainfall interception by forest canopy is an important process of water resources cycle in forest watershed. Most studies focused on the relationships of the interception with the precipitation in one or more rainfall events, without considering rainfall density and vegetation characteristics. By using a semi-theoretical model of canopy rainfall interception model, taking rainfall intensity and leaf area indices as inputs and canopy wetness index as parameter, and combining with Penman-Monteith equation, this paper simulated the rainfall interception by the broad-leaved Korean pine forest canopy in Changbai Mountains, and estimated the total interception of rainfall events from 1 May to 30 September 2004. The results showed that the total interception was 39.96 mm, occupying 10.2% of the precipitation, and the estimated results agreed well with the measured ones. Based on the estimated results, the relationships between interception and rainfall on different temporal scales were analyzed, which suggested that with the increase of temporal scale from 30 min to a month, the correlation between interception and rainfall became more and more obvious.

China↗
PubMed2003

Development of interception of moving targets by chimpanzees (Pan troglodytes) in an automated task.

The experiments investigated how two adult captive chimpanzees learned to navigate in an automated interception task. They had to capture a visual target that moved predictably on a touch monitor. The aim of the study was to determine the learning stages that led to an efficient strategy of intercepting the target. The chimpanzees had prior training in moving a finger on a touch monitor and were exposed to the interception task without any explicit training. With a finger the subject could move a small "ball" at any speed on the screen toward a visual target that moved at a fixed speed either back and forth in a linear path or around the edge of the screen in a rectangular pattern. Initial ball and target locations varied from trial to trial. The subjects received a small fruit reinforcement when they hit the target with the ball. The speed of target movement was increased across training stages up to 38 cm/s. Learning progressed from merely chasing the target to intercepting the target by moving the ball to a point on the screen that coincided with arrival of the target at that point. Performance improvement consisted of reduction in redundancy of the movement path and reduction in the time to target interception. Analysis of the finger's movement path showed that the subjects anticipated the target's movement even before it began to move. Thus, the subjects learned to use the target's initial resting location at trial onset as a predictive signal for where the target would later be when it began moving. During probe trials, where the target unpredictably remained stationary throughout the trial, the subjects first moved the ball in anticipation of expected target movement and then corrected the movement to steer the ball to the resting target. Anticipatory ball movement in probe trials with novel ball and target locations (tested for one subject) showed generalized interception beyond the trained ball and target locations. The experiments illustrate in a laboratory setting the development of a highly complex and adaptive motor performance that resembles navigational skills seen in natural settings where predators intercept the path of moving prey.

Animals↗
PubMed1991

The y-intercept of the critical power function as a measure of anaerobic work capacity.

When bouts of muscular work are performed to exhaustion at different intensities, the slope of the regression of maximal work (work limit) on maximal time (time limit) is referred to as critical power (CP). The y-intercept of this function is considered to represent anaerobic work capacity (AWC). The purpose of this investigation was to examine the relationship between the y-intercept from the critical power curve and measures of AWC (total work accomplished, maximal blood lactate and post-exercise venous blood pH) gained from repeated, maximal exercise. Nine male volunteers of moderately high training status (VO2 max 4.45 +/- 0.251/min) completed three cycle ergometer tests to exhaustion (at 300, 350 and 400 W) for the determination of CP. A second cycle ergometer task involved repeated maximal effort (against 0.075 N/kg body mass) over five 1 min periods. Five min of passive recovery separated each exercise bout, at the end of which capillary blood was collected for lactate analysis. On completion of the fifth bout, venous blood was sampled for the determination of blood pH. Total accumulated work provided a performance estimate of AWC which, together with blood lactate and pH, was compared to the y-intercept. Correlation analysis revealed a significant relation between the y-intercept and total work accomplished (r = 0.74; p less than 0.05), while post-exercise venous blood pH was positively related to both the y-intercept (r = 0.92; p less than 0.01) and the accumulated work recorded (r = 0.92; p less than 0.01). No significant correlation between peak blood lactate and work was found (r = 0.16; ns), although a relation between post-exercise venous blood pH and VO2 max was established (r = 0.84; p less than 0.05). The capacity for high intensity interval work was well represented by the y-intercept in active males. Furthermore, the relations between blood pH and both the y-intercept and accumulated work suggest that either improved buffering or a greater contribution of aerobic metabolism to the energy yield may have been responsible for the more successful performances in the interval exercise.

Acid-Base Equilibrium↗
PubMed2007

Above-ground biomass investments and light interception of tropical forest trees and lianas early in succession.

BACKGROUND AND AIMS: Crown structure and above-ground biomass investment was studied in relation to light interception of trees and lianas growing in a 6-month-old regenerating forest. METHODS: The vertical distribution of total above-ground biomass, height, diameter, stem density, leaf angles and crown depth were measured for individual plants of three short-lived pioneers (SLPs), four long-lived pioneers (LLPs) and three lianas. Daily light interception per individual Phi(d) was calculated with a canopy model. The model was then used to estimate light interception per unit of leaf mass (Phi(leaf mass)), total above-ground mass (Phi(mass)) and crown structure efficiency (E(a), the ratio of absorbed vs. available light). KEY RESULTS: The SLPs Trema and Ochroma intercepted higher amounts of light per unit leaf mass (Phi(leaf mass)) because they had shallower crowns, resulting in higher crown use efficiency (E(a)) than the other species. These SLPs (but not Cecropia) were also taller and intercepted more light per unit leaf area (Phi(area)). LLPs and lianas had considerably higher amounts of leaf mass and area per unit above-ground mass (LMR and LAR, respectively) and thus attained Phi(mass) values similar to the SLPs (Phi(mass)=Phi(area)xLAR). Lianas, which were mostly self-supporting, had light interception efficiencies similar to those of the trees. CONCLUSIONS: These results show how, due to the trade-off between crown structure and biomass allocation, SLPs, and LLPs and lianas intercept similar amount of light per unit mass which may contribute to the ability of the latter two groups to persist.

Biomass↗
PubMed2004

Neural responses during interception of real and apparent circularly moving stimuli in motor cortex and area 7a.

We recorded the neuronal activity in the arm area of the motor cortex and parietal area 7a of two monkeys during interception of stimuli moving in real and apparent motion. The stimulus moved along a circular path with one of five speeds (180-540 degrees/s), and was intercepted at 6 o'clock by exerting a force pulse on a semi-isometric joystick which controlled a cursor on the screen. The real stimuli were shown in adjacent positions every 16 ms, whereas in the apparent motion situation five stimuli were flashed successively at the vertices of a regular pentagon. The results showed, first, that a group of neurons in both areas above responded not only during the interception but also during a NOGO task in which the same stimuli were presented in the absence of a motor response. This finding suggests these areas are involved in both the processing of the stimulus as well as in the preparation and production of the interception movement. In addition, a group of motor cortical cells responded during the interception task but not during a center --> out task, in which the monkeys produced similar force pulses towards eight stationary targets. This group of cells may be engaged in sensorimotor transformations more specific to the interception of real and apparent moving stimuli. Finally, a multiple regression analysis revealed that the time-varying neuronal activity in area 7a and motor cortex was related to various aspects of stimulus motion and hand force in both the real and apparent motion conditions, with stimulus-related activity prevailing in area 7a and hand-related activity prevailing in motor cortex. In addition, the neural activity was selectively associated with the stimulus angle during real motion, whereas it was tightly correlated to the time-to-contact in the apparent motion condition, particularly in the motor cortex. Overall, these observations indicate that neurons in motor cortex and area 7a are processing different parameters of the stimulus depending on the kind of stimulus motion, and that this information is used in a predictive fashion in motor cortex to trigger the interception movement.

Algorithms↗
PubMed1993

Simulated influence of leaf geometry on sunlight interception and photosynthesis in conifer needles.

The light interception capabilities of individual conifer needles are governed by their cross-sectional geometry and their orientation to sunlight. Leaf cross sections typical of conifer tree species were modeled to quantify the interception of direct sunlight over a range of incident light angles. The needle shapes exhibited by Abies nordmanniana Spach, Picea asperata Master, Pinus cembra L., P. monophylla Torr & Frém., and P. sylvestris L. were selected because they are representative of the range of geometric shapes found in conifer tree species. Calculated light interception values were compared to corresponding predictions for a laminar broadleaf. Estimates of carbon gain were derived from computed incident light integrated over the leaf cross section and a representative curve of conifer photosynthetic response to light. Flat leaf cross sections (e.g., Abies nordmanniana) with high surface area to volume ratios (> 6) intercepted more light per unit area at high angles of incidence than thick leaves. Thick leaves (e.g., Pinus cembra) intercepted more light at low angles of incidence than at high angles of incidence. Needles of Pinus monophylla had no angular dependence for light interception because of their circular cross section. Large differences in estimated CO(2) assimilation occurred among the species, especially when CO(2) uptake was expressed on a unit volume basis. A maximum uptake of 67.9 mmol CO(2) m(-3) s(-1) was predicted for A. nordmanniana compared to a minimum of 39.7 mmol m(-3) s(-1) for P. monophylla. A greater angular dependence occurred for estimates of CO(2) uptake than for estimates of light interception.

Journal Article↗