bluuebunny/crossref_metadata_2025 huggingface dataset:
The Impact of Computer Aided Architectural Design on Physical Reality
Authors: Schmitt Gerhard
Published: May 2006

Computer Aided Architectural Design (CAAD) has produced three types and three generations of CAAD researchers, teachers and practitioners. The three types – CAAD inventors, implementers and users – benefit from the constantly improving computer technology. The three generations – CAAD pioneers, trendsetters and educators are in a more difficult situation as the attitude towards, and the knowledge about, Computer Aided Architectural Design in the general public and in the professional community is unstable. To explore the impact of CAAD on physical reality and to discover future challenges, it is useful to look at the pioneers of CAAD, as they often combine in one person the characteristics of the development that occurred afterwards. Tom Maver is one of the premier examples. The paper presents thoughts on CAAD teaching and research and contrasts them with the professional reality at ETH, in order to explore the impact of CAAD on the physical reality.
Back to the Future: Performative Architecture
Authors: Kolarevic Branko
Published: May 2006

The paper addresses performative architecture as an emerging design paradigm in which building performance, broadly understood, becomes a guiding design principle. It traces the origins of this approach to design to Tom Maver's visionary work in early seventies, discusses the inadequacy of existing building performance simulation tools in conceptual design, and proposes the development of software that can provide dynamic processes of formation based on specific performance objectives.
A Nobel Prize for CAAD
Authors: de Vries Bauke
Published: May 2006

Fundamental questions about the status of CAAD research arise regularly on different levels and under different circumstances. Apparently there is no common understanding about this, causing confusion, which in itself is already bad for the status of CAAD research. In this article I will discuss the CAAD research approach as I find it at most architecture and engineering groups, by comparing it to research in the traditional science domain. Some differences can be explained from the nature of design, but others' have more historical reasons. To conclude I propose a long-term strategy for scientific CAAD research, namely: (i) Build your own community, (ii) Establish prestigious journals and prizes and (iii) Improve quality by natural selection. Eventually this will bring us the recognition for CAAD research that it deserves.
Visualising the Structure of Architectural Open Spaces Based on Shape Analysis
Authors: Rana Sanjay , Batty Mike
Published: May 2006

This paper proposes the application of some well known two-dimensional geometrical shape descriptors for the visualisation of the structure of architectural open spaces. The paper demonstrates the use of visibility measures such as distance to obstacles and amount of visible space to calculate shape descriptors such as convexity and skeleton of the open space. The aim of the paper is to indicate a simple, objective and quantifiable approach to understand the structure of open spaces otherwise impossible due to the complex construction of built structures.
Problem Framing in Multiple Settings
Authors: Kvan Thomas , Gao Song
Published: May 2006

This study offers an insight to architectural students' problem framing activities using digital and paper media. The role of problem framing in design processes and its contribution to design learning has been studied by others. Here, we investigate the effects of media on framing activities. Laboratory experiments were conducted to investigate problem framing under three settings, namely online co-located, online remote and paper-based co-located. Student pairs were asked to spend forty minutes in solving collaboratively a wicked design problem. The results show that problem framing activities are significantly different in the online remote setting compared to those in the two co-located settings. We find more density of framing activities happened in the online remote setting than in the other two settings while there is no significant difference between online co-located and paper-based co- located settings.
3D Crossover: Exploring Objets Digitalisé
Authors: Schnabel Marc Aurel , Kvan Thomas , Kuan Steve K.S. , Li Weidong
Published: May 2006

By merging a range of digital and physical media, the architectural design process is enriched by different perceptions, comprehensions and conceptions of spatial volumes within both physical and virtual environments. The use of digital media often confines the design process to only the digital realm; in this class, students moved fluidly back and forth from digital to physical using digital tools in unorthodox ways. These different media transformed the design process from a tangible portrayal of architectural design to a virtual portrayal, and vice versa. With this interchanging and crossing over of design environments from reality to virtuality the limits of each one are dismantled, both realms can be brought together in an overall process that led to alternative form findings and resulting designs. This work lies in the tradition of artists who push media to explore new interpretations both of the media themselves and of their artwork.
Combing Grammars and Space Syntax: Formulating, Generating and Evaluating Designs
Authors: Heitor Teresa V. , Duarte José P. , Pinto Rafaela M.
Published: May 2006

This paper is concerned with how two different computational approaches to design – shape grammars and space syntax – can be combined into a single common framework for formulating, generating, and evaluating designs. The main goal is to explore how the formal principles applied in the design process interact with the spatial properties of the designed objects. Results suggest that space syntax is (1) useful in determining the universe of solutions generated by the grammar and (2) in evaluating the evolving designs in terms of spatial properties and, therefore, in guiding the generation of designs.
Assessment of the Use of 3D- Viewing and Mark-up Tool for Rich Network Design Communication
Authors: Morozumi Mitsuo , Homma Riken
Published: May 2006

Though there have been many successful examples of Virtual Design Studio, there still exist unsuccessful cases in which participants felt dissatisfied or even frustrated, especially at synchronous stages of design_communication. A discussion that required designers to refer to 3D models was one of the situations where technical support was insufficient to satisfy the expectation of designers. Assuming that an interactive viewing of 3D models and use of a mark-up utility on a shared PC window could enhance such design communications (though this also requires network bandwidth and computational power) the author conducted experiments in design discussion between two designers to test the capability and effects of these tools for network collaborations. This paper discusses the framework and results of the experiments, and proposes the next step for system developments.
The Kaléidoscope System to Organize Architectural Design References
Authors: Scaletsky Celso Carnos
Published: May 2006

The presentation of a new computer-based tool to assist architectural conception demands reflection on the process of creation itself. There is an articulation between typical conceptual procedures and computerized means. We chose one of these procedures: the utilization of external references (not necessarily architectural) to stimulate new design ideas. This is the basis for the experimental computational model “kaléidoscope”, which is characterized as an open reference system for architectural design. There are two essential qualities for such a system: 1) The system should permit an individual interpretation and construction of the referential knowledge, considering that 2) references may proceed from fields other than architecture. The computational model begins with a reference, formed by the association of an image to concepts and / or texts. The concepts are graphically represented and organized in thematic thesauri. The “kaléidoscope” system includes several search and navigation modes, allowing access to references as a means to rouse new design ideas.
Dynamical Structural Modeling: A Collaborative Design Exploration
Authors: Burry Jane , Felicetti Peter , Tang Jiwu , Burry Mark , Xie Mike
Published: May 2006

This study is based on a generative performative modeling approach that engages architects and structural engineers in close dialogue. We focus on knowledge shared between engineers and architects to apply the Finite Element Analysis based structural design technique Evolutionary Structural Optimization [ESO] as a way to understand or corroborate the performance factors that are significant in determining architectural form. ESO is very close conceptually to the dynamical system of matter and forces of growth itself. It has parallels both mathematical and metaphorical with natural evolution and morphogenesis so it has been poignant to apply the approach to a formal architectural case study in which the generative influence of these processes is inherent.
Interactive Space Generation through Play Exploring the Role of Simulation on the Design Table
Authors: Schieck Ava Fatah gen , Penn Alan , Mottram Chiron , Strothmann Andreas , Ohlenburg Jan , Broll Wolfgang , Aish Francis , Attfield Simon
Published: May 2006

In this paper we report on recent developments in the use of simulation as an aspect of design decision support for architecture and planning. This research is based on ARTHUR (Augmented Round Table for Architecture and Urban Planning). Although real time simulation has been incorporated in design support systems, little attention has been given to the simulation of pedestrian movement in collaborative AR based systems. Here we report on user evaluation tests of the ARTHUR system, which are focused on the effect of real time pedestrian simulation on the way pairs of designers work together.

These tests suggest that the integration of simulated pedestrian movement on the design table plays a critical role in exploring possible design solutions and encourages different and new ways of thinking about design problems. Donald Schon's concept of the reflection-in-action provide a useful framework for interpreting these results.
Representational Thickness: A Quantitative Comparison between Physical, CAVE and Panorama Environments
Authors: Mullins Michael , Strojan Tadeja Z.
Published: May 2006

This study compares aspects of spatial perception in a physical environment and its virtual representations in a CAVE and Panorama. To measure accuracy of spatial perception, users were asked to look at identical objects in the three environments and then locate them and identify their shape on scaled drawings. Results were then statistically compared for differences. In a discussion of the results, the paper addresses three hypothetical assertions – that depth perception in physical reality and its virtual representations in CAVE and Panorama are quantifiably different; that differences are attributable to prior contextual experience of the viewer; and that design professionals and laypeople have different perceptions of what they see in VR. In conclusion, the concept of ‘representational thickness’ is suggested by the results.
Digital to Analog: Exploring Digital Processes of Making
Authors: Norman Frederick
Published: May 2006

This focus this paper is the translation of a digital information model that defines an object's surface properties and its connection to that which is real or physical. This research, while early in its investigation, seeks to explore architecture and digital design as a material process. The direct connection to output devices such as computer-numerically controlled routers provide a unique opportunity for controlled variation and serial differentiation and seeks to exploit mass customization rather than standardization. Through a series of studies the process from design to machine file to finish product is explored. This connection to digitally driven fabrication equipment creates within the design process an opportunity to realize ones designs both digitally and materially.
A Method for Constructing a Reference Image Database to Assist with Design Process. Application to the Wooden Architecture Domain
Authors: Kacher Sabrina , Halin Gilles , Bignon Jean-Claude , Humbert Pascal
Published: May 2006

Designing architectural projects requires the introduction of references, because design is an activity oriented towards a result which does not yet exist. If we summarise the current categories used in Artificial Intelligence to characterise the different forms of reasoning, we are able to consider that design is more the concern of the induction or the abduction mechanism than the deduction mechanism. Moreover, the main characteristic of the designer's activity is to work towards non-routine situations with the use of many references. In this paper we will present method principles to construct a reference image database. These references will enable the designer to further in solving the design problem. To illustrate these reference usage, we choose photographic images belonging to the wooden construction domain We also present at the end of the paper an experiment which aims to evaluate the real help that this reference image database can bring to designers during their creation task.
ARCH: DMUVR – A Working Prototype of a Distributed Collaborative Design System
Authors: Han Seung-Hoon
Published: May 2006

This paper outlines a working prototype which suggests a distributed Computer-Aided Architectural Design (CAAD) system to promote a new model of collaborative design. Recently, there has been a growing interest in distributed CAAD integration due to the needs of direct collaboration among project participants. The potential for the integration of information is expected to have a tremendous impact on architecture and the construction industry. The aim of this research is to provide a new paradigm for a CAAD system by combining research on integrated CAAD applications with recent collaboration technologies. The proposed system has been designed and a prototype implemented to produce enough guidelines to foster interest in the development of future CAAD systems on the Internet. To this end, two different scopes of implementation are evaluated: first, global architecture and the functionality of a distributed CAAD system; and, second, the association of an architectural application to the system.
Real-Time Simulations Using Learning Algorithms for Immersive Data Visualization in Buildings
Authors: Srinivasan Ravi S. , Malkawi Ali M.
Published: May 2006

Computational Fluid Dynamic (CFD) simulations are used to predict indoor thermal environments and assess their response to specific internal/external conditions. Although computing power has increased exponentially in the past decade, CFD simulations are still time-consuming and their prediction results cannot be used for real-time immersive visualization in buildings. A method that can bypass the time-consuming simulations and generate “acceptable” results will allow such visualization to be constructed.

This paper discusses a project that utilizes a supervised Artificial Neural Network (ANN) as a learning algorithm to predict post-processed CFD data to ensure rapid data visualization. To develop a generic learning model for a wide range of spatial configurations, this paper presents a pilot project that utilizes an unsupervised Reinforcement Learning (RL) algorithm. The ANN technique was integrated with an interactive, immersive Augmented Reality (AR) system to interact with and visualize CFD results in buildings. ANN was also evaluated against a linear regression model. Both models were tested and validated with datasets to determine their degree of accuracy. Initial tests, conducted to evaluate the user's experience of the system, indicated satisfactory results.
Enhancing Sport Performance: Merging Sports Science with Coaching
Authors: Meyers Michael C.
Published: May 2006

Over the years, sport science has mainly been viewed by coaches as inaccessible, too technical, or in many cases, non-applicable to the actual sport setting. With the renewed focus on prevention of injuries, on enhancing performance at the younger levels of competition, and on the extensive amount of time and financial commitment toward training and conditioning, taking a more comprehensive approach through science provides the coach, as well as the athlete, greater control, preparation, accountability and, most importantly, measurable progress. It is the merging of ‘science and sweat’ that will allow today's athletes to not only excel and compete at much higher levels, but minimize predisposition to injury and enhance career longevity. This article describes and revisits some scientific areas and tools to add to a coach's present arsenal of assessments, and discusses the advantages, complexities, and concerns in the continually evolving area of sport science.
Exercise Science and Coaching: Correcting Common Misunderstandings about Endurance Exercise
Authors: Bosch Andrew N.
Published: May 2006

Many coaches who work with endurance athletes still believe in old concepts that can no longer be considered correct. Prime amongst these are the understanding, or misunderstanding, of the concepts of maximal oxygen uptake (V̇DO2 max), lactate threshold, training heart rate, and dehydration and fluid requirements during prolonged exercise.

Knowing the V̇DO2 max of an athlete is not particularly useful to the coach, and the exact V̇DO2 max value of any particular athlete can vary considerably as fitness changes. Race performance is a more useful measure on which to base training schedules.

Lactic acid production, far from being an undesirable event, is of great importance and is actually beneficial to the athlete. The lactate concentration during exercise, and the lactate turnpoint, are both widely measured. The nature of the information that these measures can provide about training and training status, however, is still based on information from the 1980s, although more current information is available and many of the original concepts have been modified.

Heart rate is often used to prescribe training intensity, but it is important to understand the limitations inherent in its use. If used correctly, it is a useful tool for the coach.

Similarly, many athletes and coaches still believe that it is necessary to maintain a high fluid intake to avoid dehydration and prevent associated collapse. These beliefs are incorrect, but modern exercise science has been able to advance the knowledge in this area and provide more accurate information.

Exercise science continues to progress and can offer much to the coach willing to accept new and changing ideas.
The Self-Monitoring of Expert Sport Instructors
Authors: Schempp Paul G. , McCullick Bryan A. , Busch Christopher A. , Webster Collin , Mason Ilse Sannen
Published: May 2006

This study identified the major facets of professional practice monitored by expert teachers. Specifically the skills and knowledge expert sport instructors regularly scrutinized in order to improve their teaching and coaching were categorized and examined. Data were collected from 31 teachers listed by Golf Magazine as the Top 100 Golf Instructors in America. The teachers listed aspects of their teaching they regularly monitored in assessing their own strengths and weaknesses. Data were analyzed in three steps. First, responses were reviewed to identify the characteristics monitored by the teachers. Second, characteristics grouped under each theme were reviewed and clustered into representative categories. Third, all categories were reviewed to ensure every characteristic identified by the teachers was accounted for by theme or category, and that the investigators unanimously agreed to the coding of each characteristic From this process, five themes were constructed that represented the activities and qualities most often monitored by expert teachers: (a) skills (i.e., things teachers do), (b) knowledge base (i.e., things teachers know), (c) personal characteristics (i.e., things teachers are), (d) philosophy (i.e., things teachers believe), and (e) tools (i.e., things teachers use).
A Structural Model on the Determinants and Reactions to Athlete Dissatisfaction
Authors: Voight Mike , Callaghan John
Published: May 2006

Anecdotal evidence indicates that collegiate athletes who are dissatisfied are more likely to transfer, quit, stage player mutinies, get the head coach fired, and engage in physical violence.

Although the causes of satisfaction in sport have been addressed by a few researchers, there has been no empirical attention given to what occurs when an athlete is not satisfied. The purpose of the present study was to test a sport-specific model on personal and situational variables, determinant factors, and consequential reaction alternatives.

Since the causes and consequences of job satisfaction-dissatisfaction have been popular topics for research in the field of industrial-organizational psychology, this literature was utilized to develop the basis for this investigation. Questionnaires were administered to 369 male and female Division I college soccer players. Structural equation modeling results demonstrated that the proposed model adequately fit the sample data. As predicted, numerous significant effects were indicated which linked personal and situational variables to both determinant factors and adaptive-maladaptive consequential alternatives. For example, discrepancies in coaching behaviors lead to dissatisfaction with coaches, which then leads to the use of maladaptive alternatives. This represents negative influences on the athletes' behavioral, psychological, and emotional well-being. Based upon the significant effects, implications for dissatisfied athletes, their coaches, support staff, and athletic administrators are presented.
Developmental Paths and Activities of Successful Sport Coaches
Authors: Gilbert Wade , Côté Jean , Mallett Cliff
Published: May 2006

The purpose of this research report is to present an overview of an ongoing, international project designed to chart the developmental paths and activities of sport coaches. This brief report includes three sections: (a) conceptual framework used to guide the project, (b) project design and methodology, and (c) results from pilot studies with a sample of 15 successful coaches working in different sport contexts in the United States Unlike the findings for athletic profiles, where several trends across coaching contexts were evident, only one trend was found in how these diverse groups of coaches invested their time in coach developmental activities. In relation to other coaching activities very little time was devoted to formal coach education on an annual basis. The results reinforce the need to consider the coaching context when examining coach development and when designing coach development initiatives.
Factor V Leiden, prothrombin G20210A substitution and hormone therapy: indications for molecular screening
Authors: Andreassi Maria Grazia , Botto Nicoletta , Maffei Silvia
Published: May 2006

Venous thromboembolism is a well-known complication of oral contraception and hormonal replacement therapy. Inherited thrombophilia is viewed as an important determinant in modulating the effects of estrogens on thrombotic risk. An increasing number of kits for thrombophilic mutations [factor V Leiden, G20210A prothrombin and methylenetetrahydrofolate reductase (
Molecular detection of squamous cell carcinoma antigen transcripts in peripheral blood of cancer patients
Authors: Buyru Nur , Tigli Hatice , Duranyildiz Derya , Dalay Nejat
Published: May 2006

The squamous cell carcinoma antigen (SCC-Ag) has been widely applied as a serum marker in different kinds of cancer and was reported as a target gene for the detection of tumor cells in peripheral blood in cervical cancer. Nucleic acids released into the circulation are non-invasive diagnostic tools for cancer detection. The objective of this study was to determine the utility of SCC-Ag mRNA as a cancer detection marker in blood of cancer patients. For this purpose, 77 blood samples from five gastric cancer, 23 laryngeal cancer, 31 lung cancer, nine esophageal, and nine cervical cancer patients were analyzed. The
Thermomechanische Belastungstechnik zur Analyse von Materialeigenschaften in Mikrosystemverbunden (Thermomechanical Loading Setup for the Analysis of Micro Materials Parameter in MEMS Compounds)
Authors: Dost Michael , Seiler Bettina , Erb Rolf
Published: May 2006

Die Zuverlässigkeit von Mikrosystemen wird stark von thermomechanischen Alterungs- und Versagensmechanismen beeinflusst, die die hauptsächliche Ursache für Ausfälle im Langzeiteinsatz darstellen. Besonders im Bereich hoher Lebensdauern spielt die Stabilität der Material- und Interfaceeigenschaften im strukturierten Komponentenverbund eine prägende Rolle. Zur Ermittlung der oft noch unzureichend bekannten Materialeigenschaften im Verbund und zur Analyse von Versagens- und Alterungsvorgängen ist eine kombinierte Vorgehensweise aussichtsreich, die die experimentelle Deformationsanalyse mittels optischer Verfahren, eine definierte mechanische, thermische oder gekoppelt thermomechanische Belastung und die numerische Simulation in ein übergreifendes Bewertungstool integriert. Eine für derartige Aufgabenstellungen dimensionierte modulare und erweiterungsfähige thermische Belastungseinrichtung wird im Zusammenwirken mit hochsensitiven optischen Messverfahren und numerischen Simulationsmethoden vorgestellt.
Pleustonic communities with Lemnaceae in South America
Authors: Landolt Elias
Published: May 2006

Abstract. Ca. 360 relevés of pleustonic vegetation were recorded in South America between 1983 and 1996.245 relevés, containing three or more pleustonic species, were classified according to the methods of Braun‐Blanquet. Within the class Lemnetea (minoris) the following two orders with alliances (All.) and associations (Ass.) can be distinguished:

1. Lemnetalia gibbae

  All. Azollo filiculoides‐Lemnion gibbae Ass. Lemno minutae‐Lemnetum gibbae Azollo filiculoides‐Wolffielletum oblongae

2. Lemnetalia aequinoctialis

  All. Salvinio minimae‐Lemnion minutae Ass. Lemno minutae‐Wolffielletum lingulatae

  All. Salvinio minimae‐Lemnion aequinoctialis

    Ass. Lemno aequinoctialis‐Wolffielletum lingulatae Lemno aequinoctialis‐Wolffielletum welwitschii

  All. Woljfio columbianae‐Lemnion obscurae

    Ass. Woljfio globosae‐Lemnetum obscurae The occurrence of the four alliances is mostly dependent on climate and geographical situation. The usefulness of creating pleustonic unities is discussed.
Fire as a tool in the management of a savanna/dry forest reserve in Madagascar
Authors: Bloesch Urs
Published: May 2006

Abstract. The possible use of fire for the management of the Ankarafantsika Reserve in the northwest of Madagascar and of its surrounding area is studied. Within this savanna landscape large parts of the remaining dry forests still exist with a unique biotic diversity, both in terms of total number of species and endemism. Unfortunately, mainly man‐induced uncontrolled fires threaten these forests.

Actual and former fire regimes of the local communities are analysed. The use of fire is an integrated part of land use and is also governed by socio‐cultural traditions. The impact of fire on the dynamics of dry forests and grass savannas is studied considering the specifics of different fire regimes. We propose that a deliberate and controlled use of fire respecting the vegetation stage and the defined objectives could be an appropriate management tool. The strategy of a fire management is elaborated considering both the conservation of biodiversity and improvement of the livelihood of the local population depending upon the Reserve's resources. Obviously, a sustainable management of the natural resources requires a substantial participation of the community.
Can grassland plant communities be preserved on road and railway verges?
Authors: Tikka Päivi M. , Koski Piia S. , Kivelä Reija A. , Kuitunen Markku T.
Published: May 2006

Abstract. Semi‐natural grasslands are a threatened biotope type in many countries. Typical grassland plant species are adapted to continuous grazing or mowing that keeps the environment open. With the decline in grassland area, these species are ever more reliant on alternative habitats such as road verges. To find out whether plant communities comparable to those of semi‐natural grasslands can be maintained on modern road and railway sides, the vegetation of 92 grasslands and 90 road and railway verges was studied. These biotope types were compared with each other according to their community structure, total number of species, number of grassland species and restricted‐range diversity. Further study of the vegetation of road and railway verges was carried out in order to identify the treatments and environments which are most likely to support diverse plant communities. The species number and the restricted‐range diversity proved to be higher next to roads and railways than on grasslands. Grassland species were, however, most abundant on grasslands. Furthermore, the community structure of these biotope types was totally divergent. In their present state, road and railway verges are not a substitute for semi‐natural grasslands. Nevertheless, the occurrence of grassland species in verges may be enhanced by a suitable mowing regime, by giving up the use of de‐icing salt and herbicides and by allowing natural establishment of vegetation on the verges.
Vegetation re‐establishment on land previously subject to control of Pteridium aquilinum by herbicide
Authors: Pakeman Robin J. , Thwaites Rachael H. , Le Duc Mike G. , Marrs Rob H.
Published: May 2006

Abstract. Vegetation development after conventional bracken control with herbicide in the uplands is often slow and rarely results in the development of the target community. Two experiments were established on contrasting sites to investigate cost‐effective methods for the re‐establishment of vegetation dominated by Calluna vulgaris (heather), which is the usual target community seen as the desired replacement for Pteridium aquilinum in the uplands by many land managers. At one site, where grazing intensity was low and shelter was sufficient to prevent rapid Pteridium litter loss, the necessary treatments to establish Calluna were to disturb the litter and add a source of Calluna seeds. A difference between continued Pteridium control or a relaxation of control was not observed over the time‐scale of the experiment. At the second site, where grazing intensity was high and shelter minimal, vegetation dominated by Rumex acetosella had developed on a thin but dense litter layer. To enhance Calluna regeneration it was necessary to prevent sheep grazing, disturb the remaining litter layer and add a source of Calluna propagules. A nurse crop hindered Calluna establishment due to its vigorous growth. At neither site was an initial application of fertilizer an aid to Calluna establishment.

It is possible to devise methods for the re‐establishment of Calluna at sites where previous attempts at Pteridium control alone have not had the desired effect on vegetation development. However, the precise choice of methods used is dependent on the grazing management at the site. High levels of livestock grazing prevented Calluna establishment, but some trampling may aid litter breakdown. The ability to adjust stocking rates and access to the site by machinery are critical factors to take into account in producing an effective strategy for long‐term Pteridium control and its replacement by target vegetation.
Weed community responses in a corn‐soybean intercrop
Authors: Gomez Proserpina , Gurevitch Jessica
Published: May 2006

Abstract. Weed community responses were examined in a corn‐soybean intercrop in southwestern Michigan, USA, with and without nitrogen fertilization. Weed suppression was observed when intercropping was additive, but the depression in above‐ground weed biomass was not due to a synergistic effect of crop diversity, but rather to the effects of crop density and identity. Intercropping did not have a greater suppressive effect than monocrops on weed biomass in a replacement intercrop when crop densities were similar to those in monocultures. Similarly, intercropping per se did not alter the diversity, species richness or composition of the weed community. The presence and density of corn was more important in affecting the weed community than was the density of soybeans or than intercropping itself. Fertilization and the interaction between fertilization and crop type had few effects on the weed community.
Allelopathic Potential of the Dominant Vegetation of Western Washington
Authors: Moral Roger Del , Cates Rex G.
Published: May 2006

Forty plant species common in western Washington were investigated for the presence of allelopathic chemicals capable of influencing the distribution of subordinate species. Under laboratory conditions most species contained inhibitory volatile compounds and many contained effective water—soluble compounds. The results of up to 13 bioassays per species were compared with descriptions of the distribution of subordinate species under natural conditions. In several cases, notably Acer circinatum, Arbutus menziesii, and Rhododendron albiflorum, high inhibition values in laboratory experiments were associated with distinct changes in ground—cover composition beneath the canopy of these species. The ratio between inhibition values produced by volatile and water—soluble inhibitors was higher in species from arid regions than in those from humid regions. This finding supports Muller and Whittaker's hypothesis that allelopathic compounds are primarily waste products.
Activity Patterns of Young White‐Tailed Deer Fawns in South Texas
Authors: Jackson Rodney M. , White Marshall , Knowlton Frederick F.
Published: May 2006

We studied the activity of 27 young white—tailed deer (Odocoileus virginianus) fawns on the Welder Wildlife Refuge in South Texas. we attached motion—sensitive radiotransmitters to 15 male and 12 female fawns, 3—12 day old,and monitored their activity for as long as 9 weeks. These fawns primarily were diurnal, although most were active for short periods once or twice a night. The amount and timing of activity of each fawn varied considerably; however, total activity increased with age as a fawn became stronger and more agile. Males were more active than females during daytime and in total at all ages, but females were more active at night. During their first two weeks of life, fawns were active an average of 8% of the time. By 1 month of age, males were active about 16% of the time, and females were active 12% of the time. The average number of daytime activity periods increased from two in fawns during their first week to five—six periods at 1 month of age. Most activity periods were less than 35 minutes long, but they increased in duration with fawn age. Two—hour activity periods were rare until fawns were more than a month old. The increase in fawn activity with age was related to the fawn's increasing ability to follow its dam, and its gradual integration into the adult deer social unit. Fawns were more active during midday hours in their first week of life, but they were most active in morning and evening thereafter.
Benthic Substrates: Their Effect on Fresh‐Water Mollusca
Authors: Harman Willard N.
Published: May 2006

Mollusks have been collected in 650 locations in central New York State since 1966 in order to determine habitat preferences of the various species. Chemical and physical data were recorded at each locality. Three large lakes (Skaneateless, Otsego, and Oneida) were studies in detail to observe patterns of molluscan distribution. The species associated with different bottom types are tabulated. Mollusks are substrate distribution in typical environments are discussed. The lake studies show that definite relationships exist between mollusk distribution and substrate pattern. Species diversity is correlated with substrate diversity (r = 0.79) in 348 collection are that include several biotypes.
Transandean Distributions of Bromeliaceae in Ecuador
Authors: Gilmartin Amy Jean
Published: May 2006

The distributions of members of the tropical plant family Bromeliaceae with their soil—nutrient independence are especially linked to microclimate and are valuable indicators of microclimatic regimes. Meteorological records show that the annual rainfall on the eastern slopes of the Ecuadorian Andes is higher and more evenly distributed than on the western slopes, which receive very little precipitation during several months of the year. Seventeen of the 249 Ecuadorian species of Bromeliaceae are known from collection records to be distributed on both the eastern and western slopes of the Andean Cordillera. On the eastern slopes, individuals of these species have been consistently collected at lower altitudes than on the western slopes. The more even distribution of precipitation throughout the year and the smaller range in relative humidity on the eastern slopes is apparently responsible for the strikingly lower elevations of the species' distributions on most of the eastern slopes.
A Device for Measuring the Average Temperature of Water, Soil, or Air
Authors: Brown James M.
Published: May 2006

It is possible to directly measure average temperature with a simple electronic circuit and avoid the usual time—consuming arithmetic integration of temperature records. Instructions are given for the construction of an electronic integrating thermometer composed of a thermistor in a simple Wheatstone bridge and a mercury coulometer that provides a direct readout of the average temperature of soil, air, or water over a designated time interval.
Sex Differences in the Cannibalistic Roles of Adult Flour Beetles
Authors: Mertz David B. , Cawthon D. A.
Published: May 2006

Adult males of the flour beetles Tribolium confusum and T. castaneum were found to be several times more voracious than were females as cannibals of pupae. This is exactly the reverse of the sex differences reported earlier with regard to egg—eating; as egg cannibals, females excel males by 7 to 19 times. This is a remarkable division of labor between the two sexes with respect to cannibalistic self—regulation of numbers.
Comparison of Two Light Meters for Studies of Light Penetration into Herbaceous Leaf Canopies
Authors: Fick Gary W.
Published: May 2006

A cadmium sulfide photoresistor and a selenium photovoltaic cell were compared for measuring the relative light conditions within an herbaceous leaf canopy. Under the same conditions, differences between meters as high as 30% were found for the measured light environment. Canopy disturbance was considered the major cause of the differences. Unfortunately, sensor size and spectral response were confounding factors, but differences were significant and point out both the magnitude of possible differences and the importance of exercising caution in comparing readings taken with different meters.
Ecological Implications of Annual Variation in Tidal Extremes
Authors: Bleakney J. Sherman
Published: May 2006

Analysis of extreme tides in the Bay of Fundy, Canada, for the period 1899—1971, coupled with field observations, indicates the presence of a complex of environmental variables. Extreme tides expose organisms to a variety of stresses depending upon the time of year and weather conditions; but, as both weather and tidal extremes are acylic relative to the life span of short—lived species, there is not opportunity for genetic selection of suitable behavioral responses, such as those associated with seasonal changes in light and temperature. consequently, eulittoral organisms, particularly those in the broad fringes such as salt marshes and mud flats, can be "caught off guard" at any stage of their life history. the destruction of bird nests and stranding of fish are common examples. There can be a 4—year interval between such dramatic occurrences followed then by a 17—year interval. Observations and conclusions based on short—term studies could be significantly different from previous and subsequent reports.
A Computational Strategy for System Identification in Ecology
Authors: Leary Rolfe A. , Skog Kenneth E.
Published: May 2006

A computational strategy useful for system identification studies in ecology is described. The general methodology and capabilities of the strategy are exhibited by solving several example problems.
Structure and Cation Content of a Podzolic Soil of Long Island, N. Y., Seven Years After Destruction of the Vegetation by Chronic Gamma Irradiation
Authors: Horrill A. D. , Woodwell G. M.
Published: May 2006

Chronic gamma irradiation of an oak—pine forest in central Long Island, New York, has reduced the structure of the forest systematically and started changes in the structure and nutrient content of the soils. The most important changes have been reduction of the litter and humus horizons and a decline in loss—on—ignition in most horizons. Nutrient content of soils has clearly been augmented by minor disturbance of the vegetation and reduced by more severe disturbance. The soil content of phosphorus and calcium were exceptions, increasing along the gradient of radiation toward the highest exposures.
A Home‐Range Model for Animals Inhibiting and Ecotone
Authors: Van Winkle Webster , Martin Donald C. , Sebetich Michael J.
Published: May 2006

A probability model and associated statistical techniques are presented which are specifically designed to analyze the home range of animals inhibiting nonhomogeneous habitats with the special characteristics of an ecotone. The utilization distribution of an individual animal is approximated with a continuous bivariate probability distribution having unimodal and independent X and Y distributions with axes parallel and at right angles to the ecotone. Statistical techniques based on this model are used to analyze a set of capture points for bullfrogs (Rana catesbeiana) inhabiting the shoreline of a pond. The approach used is applicable to other animals inhabiting other ecotones, but not to animals inhibating homogeneous habitats.
Phosphorus Kinetics of Freshwater Microcosms
Authors: Sebetich Michael J.
Published: May 2006

Laboratory microcosms were designed to study phosphorus exchange among lake water, diatoms (Nitzschia palea), snails (Physa sp.), and sand. Mathematical models describing the movement of 32P were used to simulate phosphorus behavior in microcosms of varying complexities. The single and combined effects of diatoms, snails, and sand on rate of 32P transfer were tested by factorial analysis. Phosphorus behavior varied both among microcosms of different complexities and among microcosms containing the same quantities but different compositions of compartments. All rate transfer constants involving water and one other compartment were significantly affected by another single compartment, by an interaction between two other compartments, or by both a single compartment and its interaction with another. Turnover of phosphorus was compared among different microcosms. Water generally maintained a higher turnover rate of phosphorus than any other compartment. The mean hourly turnover rate of 32P in water ranged from 0.00029 in microcosms containing water and a snail to 0.1035 in the four—compartment microcosms. Snails and diatoms tended to maintain high concentrations of 432P although there was an active exchange of 32P between each biotic compartment and water. A major exception occurred in the four—compartment systems wherein diatoms steadily lost 32P after about 24 h following inoculation of 32P, into the water. Diatoms and sand competed for, and dominated the movement of, 32P, as compared to snails which had a generally less dynamic effect on the cycle. Despite the active exchange of 32P between water and sand, the slow diffusion of 32P resulted in a net flow of 32P into sand.
Determinants of Community Structure for Coral Reef Fishes in an Experimental Habitat
Authors: Sale Peter F. , Dybdahl Rand
Published: May 2006

We examined the patterns of distribution of species of resident fishes in an experimental habitat consisting of 10 small live colonies of the coral Acropora pulchra (L—units), and 10 similar sized pieces of eroded coralline rock (D—units). Approximately every 4 mo for 2 yr, all fish in each unit were collected. Numbers collected were similar at all times to numbers in control units that were not disturbed. A total of 630 fishes and 56 species were collected; most species were rare in our sample. Greater numbers of fish and of species were collected when recruitment had taken place during summer months. Greater numbers of fish and of species were collected from L— than from D—units. Only three species were demonstrated to be seasonal in recruitment. No temperal partitioning of the habitat was demonstrated. Five common species showed marked preferences for L—units, but most species did not make this discrimination. Comparisons of samples from L—units with samples from D—units showed somewhat less faunal similarity than comparisons between samples from the same type of unit. There was no evidence that fishes occupying units of one type partitioned the habitat on the basis of precise microhabitat requirements that would have caused particular species to occur consistently in particular units. There was on indication that any pair of species mutually excluded each other from units. With the exception of those few species which distinguished D— and L—units, we conclude that the distribution of species among units is a result of chance colonization, not of a systematic partitioning of the living space provided. We anticipate this conclusion to have general validity for reef fish communities. Some consequences for our understanding of the small—scale distribution of fishes on coral reefs are discussed.
The Ecological Role of Consumers‐‐An Aggregated Systems View
Authors: Lee Jeffrey J. , Inman Donald L.
Published: May 2006

In typical temperate ecosystems, herbivores consume only a few percent of available net primary production. The implications of this fact with respect to the ecological role of consumers have been debated in the literature. In this paper, we use the techniques of system analysis to investigate the plausibility of the hypothesis that the consumer complex (including predators and parasites) acts as an ecosystem regulator. Using data obtained from an old—field dominated by Andropogon virginicus, and other published data, on aggregated ecosystem model is constructed. Simulation experiments with this model demonstrate that a subsystem related to a system as the consumers are to the ecosystem can exert a control function. In this case, time is a more important factor than either compartment size or actual amounts transferred.
Patterns of Species Diversity in Caribbean Reef Corals
Authors: Porter James W.
Published: May 2006

A method of counting chain links covering living coral is described and discussed as a means of calculating species diversity on coral reefs. Species diversity on San Blas coral reefs, Atlantic coast, Panama, shows two trends: diversity (H') increase from the surface to a peak of 3.2 at 5 m, remains between 1.5 and 3.5 down to 25 m, and then falls off to 0.0. Superimposed on this trend is an increase in diversity toward cliff edges. The cliff—edge diversity values are always higher than their corresponding back shelf values; this difference is significant at the 0.05 level for all but one of the ledges measured. In addition, the average cliff edge diversity (H' = 2.28) is significantly higher (P < 0.05) than the average back shelf diversity (H' = 1.89). Species diversity correlates strongly (P < 0.001) with both components of the species diversity formulation, species number and species evenness, indicating that both of these components are simultaneous properties of this coral reef community. Since the San Blas reefs are constructional, not erosional, in form and since corals have been shown to interact in definite competitive ways, the observed organization is under a considerable amount of biological control and the consistent, statistically significant diversity trends are indicative of an active form of coral community organization.