A Predator‐Prey System in the Marine Intertidal Region. I. Balanus glandula and Several Predatory Species of Thais

SUMMARYZonation patterns and the structure of intertidal communities are controlled by tidal conditions. Algal diversity, abundance and succession were experimentally tested under different degrees of wave exposure, shore level, and season of clearing at the intertidal zone, Phuket, Thailand. Dead coral patches colonized by algae (20 cm × 20 cm) were cleared at upper, middle, and lower shore levels on sheltered and semi‐exposed shores during both the dry and rainy seasons. Of 17 algal species, including eight Rhodophyta, eight Chlorophyta, and one Phaeophyceae that were recruited on the cleared plots, three species were dominant: Ulva paradoxa, Padina in the Vaughaniella stage, and Polysiphonia sphaerocarpa. Algal diversity on the semi‐exposed shore was higher than on the sheltered shore. In the successional process, U. paradoxa extensively recruited and persisted longer on plots cleared at the middle shore level on the semi‐exposed shores than at the other. It showed a greater abundance in the plots cleared in the rainy season than those cleared in the dry season. Ulva paradoxa persisted for around 5 to 6 months after clearing and was then replaced by the two later species, Padina in the Vaughaniella stage and P. sphaerocarpa. Ulva paradoxa settled more easily and persisted longer at the cleared plots than other algal species because of its opportunistic characteristics and a special physiological adaptation to long periods of emersion. From this study, degree of wave exposure, shore level, and season of clearing likely play important roles in algal recruitment, abundance, and succession patterns.

To evaluate how interreader agreement and the site of the volume of interest (VOI) affect the agreement and variability of liver mean standardized uptake value normalized to lean body mass (SUL(mean)) at fluorine 18 fluorodeoxyglucose (FDG) positron emission tomography (PET)/computed tomography (CT). Institutional review board approval was obtained for this HIPAA-compliant retrospective review of PET/CT images and patient records. PET/CT images were reviewed in 116 randomly selected patients who had undergone a baseline PET/CT examination and who had normal livers according to imaging and biochemical test results. A 30-mm-diameter spherical VOI was placed within the right lobe of the liver above, below, and at the level of the main portal vein. Two readers performed all measurements independently. Analysis of variance, intraclass correlation coefficient (ICC) analysis, and Bland-Altman analysis were performed. The mean SUL(mean) was between 2.11 and 2.17 at the upper, portal, and lower levels of the right lobe of the liver. The coefficient of variance was between 21.0% and 23.1%, without significant differences for location, with the least variance in the upper level. The ICC of the two readers varied between 0.98 and 0.99 (95% confidence interval [CI]: 0.97, 0.99; P = .0001) at each level. The greatest precision (narrowest CI) was also in the upper level. Bias was 0.025 ± 0.10 (standard deviation) at the upper level, was 0.004 ± 0.14 at the lower level, and was 0.047 ± 0.10 at the portal vein (P = .02). For each reader, there was almost perfect reliability between the SUL(mean) measurements made at the three levels, with an ICC of 0.98 (95% CI: 0.98, 0.99; P = .0001). Liver SUL(mean) at FDG PET/CT has excellent interreader agreement, with similar values and variance whether measured at the upper, lower, or portal vein levels within the right lobe of the liver.

In multi-objective bilevel optimisation problems, the upper-level performance of different lower-level optimal solutions may be very different, even though they belong to the same lower-level problem. It may lead to poor optimisation results. Therefore, the lower-level search should search lower-level non-dominated solutions that are also non-dominated in the upper-level objective space. In this paper, we use two populations in the lower-level search. The first population maintains non-dominance and diversity in the lower-level objective space and provides the second population with convergence pressure from the lower level. The second population selects the upper-level non-dominated solutions that are not dominated by the first population in the lower-level objective space, which make the second population maintain the non-dominance at both upper and lower levels. Besides, to improve the search efficiency, we set up the upper-level mating pool to generate the upper-level vectors of offsprings near the upper-level vectors of the better individuals in the current population. To balance convergence and diversity, the selection operator of a decomposition based multi-objective evolutionary algorithm is adopted. The proposed algorithm has been evaluated on a set of benchmark problems and a real-world optimisation problem. Experimental results demonstrate that the proposed algorithm is efficient and effective.

Using observation data and the simulations of Variational Doppler Radar Analysis System (VDRAS), the convection initiation (CI) ahead of a gust front over the Yangtze River Delta in Jiangsu province, China on 5 June 2009 was studied. The CI was located in the exit region of the upper level jet with moderate CAPE. It is found that, there was a northeast‐southwest convergence line near the ground ahead of the gust front, which could not trigger the new convection alone. The upper‐level updraft above the surface convergence line could not trigger the new convection alone either. The superposition of the updraft in the upper and low levels promoted the initiation and development of the new convective cell. Finally, the new convective cell developed continuously to the southwest and southeast, and extended to the southeast under the influence of the upper‐level wind. And the sensitivity experiments show that the surface convergence line and the upper‐level convergence were both important for the CI, especially for the strong convection. This discrete CI ahead of the gust front was influenced by a combination of low‐level and upper‐level factors. In the process of the CI, the updraft in the upper level intensified faster than that in the low level gradually. The buoyancy force was greater than the vertical perturbation pressure gradient force (VPPGF) in the low level, while the VPPGF increased faster than buoyancy in the upper level. Therefore, the dynamics of the updraft in the low and upper levels were different.

Bi-level programming and multi-objective optimization for the distribution of resources in hierarchical organizations

The ore body of the Novo-Kal'inskii bauxite deposit, which is the subject of our paper, has a dip of 28". The thickness of the ore bank varies from 0.7 m 8.5 m. In accordance with the adopted working procedure, the ore bank is divided into two levels, the mining-out work being performed simultaneously in them. In the upper level work is carried out from the upper boundary of the ore body from a depth of 295 m, in the lower level from a depth of 655 m (the postulated lower limit of the pillar) to 1060 m. An interlevel pillar is formed between the levels. Geological data show that the lower limit of the pillar is overlain at a distance of 70-150 m by water-resisting rocks. With increasing depth these rocks approach the ore body and in the depth range 500-680 m they lie at a distance of 35 to 40 m from the contact of the ore bank. One may therefore assume that as the mining-out workings advance a distance of 100-120 m from the pillar boundary, the caving zone may reach the w ater-resisting layers and the inflow of w ater into the mine workings may increase. Our aim was to determine the redistribution of the rock pressure on the interlevel pillar as the ore body was extracted, and to establish the strength of the pillar and the character and zones of occurrence of caving of the overlying rocks. We found the problem could be solved by physical modeling [1], and it was also possible to calculate the strength of a pillar Simulation by equivalent materials was done with flat beds. 4.5 m long and 0.24 m wide. With the scale used for this work, it was possible m simulate only the central part of the deposit at relative depths of 430-790 m from the surface; for this purpose we assumed that the work in the upper (295-430 m) and lower (790-1060 m) levels had little effect on the abutment pressure distribution within the limits of the postulated pillar. Initially, using the model we worked the lower level from the 655 m mark (the lower limit of the pillar) to the 790 m mark- during this period the work in the lower level must have advanced from the 295 m mark to the 430 m mark; we then worked the upper level from the 430 m mark to the upper limit of the pillar until its fracture was observed - during this period the work in the lower level must have been performed from the 790 m mark or below. To verify this assumption, we developed a model which simulated simultaneously ore extraction in the lower level from the 655 m mark to the end, and in the upper level from the 295 m mark to the upper boundary of flae pillar and to failure of the latter. The thickness of the overlying rocks to a depth of 240 m was simulated by equivalent m aterials. In these simulation procedures we assumed that the ore body had a flat pitch. It was also assumed that caving of the rocks would have approximately the same character as at a dip of 28". To reproduce the necessary depth of occurrence of the bed, the overlying roof rocks, which did not come within the scope of the model, were replaced by an increasing load. The roof displacement was measured by dial-type indicators with a scale value of 0.01 ram, resting on dowels placed in the roof of the ore body during shaping of the model The stress in the rock mass was measured by the same indicators fixed on the elastic base of the stand. The model was worked by 10 em pulls at 20 min intervals. Working of the lower level was begun from the 250 cm mark in the model (the lower limit of the pillar). To solve the problems, we processed five models, the characteristics of which are given in Table 1.

This study presents for the first time the factors governing the recruitment in a rocky intertidal community of the Beagle Channel, Tierra del Fuego (54°51′S 68°29′W), Argentina. The aim of this study was to examine the effect of grazers and predators, free substrate availability and crustose coralline algae on the recruitment of the main sessile components of the intertidal:Notochthamalus scabrosus, Notobalanus flosculus, Mytilus chilensis, Perumytilus purpuratusandAulacomya atraat three intertidal levels. For barnacles, the probability of recruitment was higher with grazers, while the contrary was observed for bivalves. The number ofN. flosculusrecruits was higher with increased substrate availability, whileN. scabrosusrecruited more with reduced free substrate in the first sampling. Mussel recruitment was higher with reduced free substrate. The highest probability of recruitment ofN. scabrosuswas observed at the upper level. Notably, this probability and the recruits per plot were higher at the mid level under uncaged-ORP treatment than expected for the mid level. The probability of bivalve andN. flosculusrecruitment was higher at upper and lower levels, respectively. At the lower level, barnacle recruitment was higher on bare rock than on crustose coralline algae. Our results suggest that grazers increase the probability of barnacle recruitment, while the presence of sessile organisms enhances the density of mussel recruits. Almost no recruitment of bivalves was observed in ORPs over one year, showing that the secondary succession is slow in this environment.

Growth rate as a measure of food value in thaidid gastropods: Assumptions and implications for prey morphology and distribution

In Mida Creek, Kenya (3°20′S, 40°5′E), at high water, the snail Cerithidea decollata dwells on the trunks of mangrove trees (Avicennia marina), while during low water it migrates to the ground, foraging at various distances from the trunk, where it aggregates again well before the incoming tide. Snails from the upper shore level are 150–200 m distant from those living at the lower shore level and they cluster at lower heights on trunks. In any case, sufficient height is usually attained to avoid being submersed. An experiment was designed (February and October 2005), exchanging individuals from different shore levels subject to different tide regimes, in order to test whether snails rely on internal information or on external, direct cues, to adapt their behaviour to local conditions. Results show that C. decollata mostly rely on internal information, presumably based on an internal clock. When individuals from upper and lower shore levels were exchanged, their internal clocks continued to govern when to ascend the home trunk and how high to climb for five to six successive tides, after which the behaviour was reset to the new local conditions.

A mechanism for electron population inversion and mid-IR amplification is proposed for the case of the current or optical injection of electron-hole pairs into the undoped region of a heterojunction with quantum wells. The presence of an upper long-lived size-quantization level and resonant Auger recombination in the well are crucial features of the mechanism. A long electron lifetime at the upper level or a relatively low probability of electron scattering to the other subbands is achieved by choosing the shape of the well and its parameters in such a way as to provide weak overlap between the upper level and two lower level electronic wave functions. Resonant Auger recombination plays a positive role. It stabilizes the electron and hole concentrations at lower levels and makes a substantial contribution to the excitation of the upper electronic level and the population inversion. The degree of population inversion and the gain coefficient are estimated.

In this article, a bi-level optimization problem covering upper (design) and lower (operation) levels is defined and a solution procedure for bi-level optimization problems is presented. This is devised as a dynamic multiobjective optimization problem, i.e. the values of the control and state variables change over a predefined time horizon and several competing criteria are optimized simultaneously. Moreover, the interaction between the upper and lower levels is analysed. The benefits of bi-level dynamic multiobjective optimization are illustrated in detail by examining an industrial case in which the design of a paper mill (upper level) and the mill operation (lower level) are optimized at the same time. However, the problem definition and the solution procedure are not limited to any specific application but can be exploited in many different industrial areas.

We studied serial CT scans of 45 arthritic shoulders (34 rheumatoid, 11 osteoarthritic) and 19 normal shoulders, making measurements at three levels on axial images. The maximum anteroposterior diameter of the glenoid was increased in rheumatoid glenoids at the upper and middle levels by 6 mm and in osteoarthritic glenoids at all levels by 5 to 8 mm as compared with normal. In rheumatoid cases, nearly half the available surface of the glenoid was of unsupported bone, mainly posteriorly at the upper and middle levels. In osteoarthritic glenoids, the best supported bone was anterior at the upper level and central at the middle and lower levels. The depth of the rheumatoid glenoid was reduced by a mean of 6 mm at the upper and middle levels and by 3 mm at the lower level. This inclined the surface of the glenoid superiorly. The depth at the middle level in osteoarthritis was reduced by a mean of 5 mm, suggesting central protrusion. Osteoarthritic glenoids were retroverted by a mean of 12.5 degrees, but of rheumatoid glenoids two-thirds were retroverted (mean 15.1 degrees) and one-third anteverted (mean 8.2 degrees). Our findings have important implications for the planning and placement of the glenoid component of total shoulder replacements; CT can provide useful information.

A methodology for performing bilevel structural optimization of aircraft wing structures is proposed. The overall design problem is decomposed into two levels: a wing (or upper) level and a panel (or lower) level. At the upper level the wing structure is evaluated and designed using a e nite element model that is less detailed and contains fewer design variables compared to the actual structure. Constraints on the overall behavior of the structure, such as aeroelastic constraints or constraints on the tip dee ection, are imposed at this level. At the lower level more detailed models of certain portions of the structure are used to compute more complex failure modes and to design the details that were not included in the upper-level model. The upper and lower design levels are coordinated with one another using a set of response surface models. Proper coordination between the two levels is maintained through the transfer of stiffness and load information from the upper design level to the lower design level. Results obtained using the proposed technique are presented for a simple wing model.

Density, size distribution, energy allocation and seasonal variations in shell and soft tissue growth at two tidal levels of a Macoma balthica (L.) population

Bahrains oldtidshovedstad gennem 4000 år