New data from Calakmul, Mexico make three principal contributions to our understanding of the ancient Maya: (1) they support the model of large regional states advocated by Marcus and Folan since the 1970s; (2) they add one more Maya site to the short list of cities linked to other cities (and to their own dependencies) by a well-planned road system; and (3) they show good fit between Central Place models and actual settlement locations.

Successful stream restoration requires the setting of appropriate goals and an ability to measure restoration success using quantitative ecological indicators. At present, a dichotomy exists between the setting of restoration goals to enhance ecosystem 'processes' or 'functions' such as sustainability, and measuring the success of these goals using 'patterns' or 'structural' ecosystem attributes. The presence of a structural facade may be no indication of a viable ecosystem as this requires evaluation of whether key ecosystem processes have been restored and whether the system is ecologically sustainable. We briefly discuss the benefits and drawbacks associated with setting restoration goals and measuring their success based on ecosystem patterns and processes. Two case studies are provided based on measurements of biofilm chlorophyll a and Dissolved Organic Carbon (DOC) to debunk the myth that these structural variables can be used as surrogates for ecosystem processes of productivity and respiration in rivers. We suggest that the discipline of restoration ecology will benefit and grow from a greater appreciation of the functional role of biological communities within stream ecosystems, and from targeting some restoration towards the reestablishment of structurally significant species and functionally significant processes. This approach to stream restoration with a well-founded conceptual base and defined scientific and management goals should expand our knowledge of stream function and contribute to the effective restoration of stream systems.

Abstract:This study has investigated the feasibility of three different solar-assisted air conditioning systems for typical medium-sized office buildings in all eight Australian capital cities using the whole building energy simulation software EnergyPlus. The studied solar cooling systems include: solar desiccant-evaporative cooling (SDEC) system, hybrid solar desiccant-compression cooling (SDCC) system, and solar absorption cooling (SAC) system. A referenced conventional vapor compression variable-air-volume (VAV) system has also been investigated for comparison purpose. The technical, environmental, and economic performances of each solar cooling system have been evaluated in terms of solar fraction (SF), system coefficient of performance (COP), annual HVAC (heating, ventilation, and air conditioning) electricity consumption, annual CO 2 emissions reduction, payback period (PBP), and net present value (NPV). The results demonstrate that the SDEC system consumes the least energy in Brisbane and Darwin, achieving 56.9% and 82.1% annual energy savings, respectively, compared to the conventional VAV system, while for the other six cities, the SAC system is the most energy efficient. However, from both energy and economic aspects, the SDEC system is more feasible in Adelaide, Brisbane, Darwin, Melbourne, Perth, and Sydney because of high annual SF and COP, low yearly energy consumption, short PBP and positive NPV, while for Canberra and Hobart, although the SAC system achieves considerable energy savings, it is not economically beneficial due to high initial cost. Therefore, the SDEC system is the most economically beneficial for most of Australian cities, especially in hot and humid climates. The SAC system is also energy efficient, but is not as economic as the SDEC system. However, for Canberra and Hobart, reducing initial cost is the key point to achieve economic feasibility of solar cooling applications.

Urbanization is acknowledged as one of the most severe threats to stream health, spawning recent research efforts into methods to ameliorate these negative impacts. Attention has focused on streams in denselypopulated cities but less populous regional urban centres can be equally prone to some of the same threats yet might not meet the conventional definitions of urban. Several recent reviews have identified the changes to streams that occur during urbanization but they note that few ecological studies have explored ecosystem-level responses, typically focusing instead on state variables such as invertebrate abundance. In many regional urban streams, changes to the extent of impervious drainage have implications for their hydrology and channel morphology but the influence of these changes on fundamental ecosystem processes of leaf litter breakdown and transport compared with those in nearby rural streams are poorly known. The widespread practice of planting exotic trees along riparian zones and street margins draining into urban streams further exacerbates the disruption of natural organic matter dynamics. The combination of seasonal leaf fall by exotic species and the altered drainage patterns through urbanization in Armidale, a regional town in New South Wales, Australia, resulted in contrasting patterns of benthic organic matter storage over 18 months compared to nearby reference and rural streams. Macroinvertebrate detritivore densities were low in the urban stream, implying disruption of the usual biological pathways of leaf breakdown. Understanding the interactions of hydrology, drainage pattern, leaf input and biological attributes of a stream is crucial for managers trying to restore stream ecosystem services without incurring public concern about the appearance of regional urban streams.

Energy-efficient housing is a product that integrates various stakeholders' tasks throughout the different stages of its life cycle. The relationships between these stakeholders impact on the degree of knowledge sharing and informed decisionmaking and can potentially enhance or lower the energy efficiency of the product -the house. This article uses a social network analysis (SNA) approach to visualize the social networks of the stakeholders of a number of owner-occupied housing case studies in Australia. The aim is to analyse, contrast and quantify the degrees of connectivity and centrality of the housing stakeholders to identify which groups have more connectivity in the stakeholders' network of energyefficiency housing and consequently more potential to influence the energy efficiency outcomes and which practices are more likely to enhance transparency and information sharing that is essential for producing energy-efficient housing.

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Las ruinas de Calakmul se encuentran en la cuenca del mismo nombre localizado dentro del 723,000 ha Reserva de la Biosfera Calakmul en el sureste del Estado de Campeche. Investigaciones del Centro de Investigaciones Históricas y Sociales de la Universidad Autónoma de Campeche han demostrado que Calakmul formaba una de las más grandes centros regionales en el área maya desde 600 a.C. hasta los fines del siglo IX dentro de su estado regional de 13,000 km2. Investigaciones de prospección remoto alrededor de Calakmul combinado con trabajos topográficos dentro de la ciudad misma han revelado 15 sac beob identificados por nosotros entre los tipos de vías terrestres descritos en los diccionarios de la idioma Maya formados durante el período colonial. Entre estos sac beob se encuentran tipos regionales, estatales y los sac beob registrados dentro de la ciudad de Calakmul. Aunque existe un traslapo entre varios tipos de sac beob, pensamos que excavaciones futuras van a ayudarnos a clasificar cada sac be en una forma más precisa.

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