Mexico City's Water Management: In Search of Sustainability

Mexico City is facing water supply problems as its population increases and aquifer overexploitation needs to be stopped. Because of its geographic location the City has continuously faced water related problems such as floods and lack of the resource. Currently the closest water sources have been already tapped and more water will be needed in the near future in order to satisfy the ever increasing demand as the aquifer systems located under the City provide nearly 75% of the total water supply. Water from the aquifers is extracted at a higher rate than they are replenished, causing a mean decline in the ground water table of one meter per year. A high percentage of water used is exported to the Panuco basin without being reused; thus, authorities are trying to implement a program to artificially recharge the aquifer using reclaimed waste water and wells in order to reduce aquifer overdraft and as an alternative to meet the ever increasing water demand. Although the main focus of the present paper is to analyze the artificial recharge program, other water policies such as efficient water use and leak detection in the water supply network will be analyzed as well along with a comparison between importing water from other river basins and use of reclaimed waste water is realized and a new approach is proposed in order to improve water management in the Basin

The Basin of Mexico Hydrogeological Database: Implementation, Queries and Interaction with Open Source Software

Integrated Water Management at the Basin level concept was introduced in the 1990s, and is a goal in every national and local water management plan. Unfortunately this goal has not been achieved mainly due to a lack of both tools and data management, as data must be gathered from different sources, and converted from diverse formats into a consistent database. Compounding this problem is the fact that in some regions different water agencies are in charge of water supply as is the case in the Basin of Mexico, in which Mexico City and its Metropolitan Zone are located. The inhabitants of the Basin of Mexico, which comprises five different political entities and in which different agencies are in charge of water supply rely on the Basins aquifer system as its main water supply source. No regional hydrogeological database in this area however exists therefore a Relational Database Management System was developed, and its use with a Geographic Information System is proposed in order to improve regional data management in the study area. Data stored in this new database (called the Basin of Mexico Hydrogeological Database) comprises data on climatological, borehole and runoff variables, readily providing information for the development of hydrogeological models. A simple example is used to show how geostatistical analysis can be done using the data directly from this database. The structure of the database supports easy maintenance and updating, representing a valuable tool for the development of regional studies

High astrometric precision in the calculation of the coordinates of orbiters in the Geo Ring

We present an astrometric method for the calculation of the positions of orbiters in the GEO ring with a high precision, through a rigorous astrometric treatment of observations with a 1-m class telescope, which are part of the CIDA survey of the GEO ring. We compute the distortion pattern to correct for the systematic errors introduced by the optics and electronics of the telescope, resulting in absolute mean errors of 0.16" and 0.12" in right ascension and declination, respectively. These correspond to ˜ 25 m at the mean distance of the GEO ring, and are thus good quality results

Mapping of mechanical properties of cement paste microstructures

The presented study is related to the EU 7 th Framework Programme CODICE (COmputationally Driven design of Innovative CEment-based materials). The main aim of the project is the development of a multi-scale model for the computer based simulation of mechanical and durability performance of cementitious materials. This paper reports results of micro/nano scale characterisation and mechanical property mapping of cementitious skeletons formed by the cement hydration at different ages. Using the statistical nanoindentation and micro-mechanical property mapping technique, intrinsic properties of different hydrate phases, and also the possible interaction (or overlapping) of different phases (e.g. calcium-silcate-hydrates) has been studied. Results of the mapping and statistical indentation testing appear to suggest the possible existence of more hydrate phases than the commonly reported LD and HD C-S-H and CH phase

Concerning the quark condensate

A continuum expression for the trace of the massive dressed-quark propagator is used to explicate a connection between the infrared limit of the QCD Dirac operator's spectrum and the quark condensate appearing in the operator product expansion, and the connection is verified via comparison with a lattice-QCD simulation. The pseudoscalar vacuum polarisation provides a good approximation to the condensate over a larger range of current-quark masses.Comment: 7 pages, LaTeX2e, revtex

Characterization and analysis of thionin genes

The general designation of thionins has been proposed for a family of homologous proteins that have been isolated from different tissues in a wide range of plant taxa and have been variously named purothionins, viscotoxins, crambins, etc. (see Garcia-Olmedo et al., 1989). The possible involvement of thionins in plant defense was first suggested, on the basis of their in vitro toxicity to plant pathogens, by Fernandez de Caleya et al., (1972). Those observations had been prompted by earlier reports concerning the antimicrobial properties of these polypeptides (Stuart and Harris, 1942; Balls and Harris, 1944). Work on the thionins, which has been actively pursued over the past half-century, has been recently reviewed in detail (Garcia-Olmedo et al., 1989). For this reason, earlier work will only be partially summarized in the present chapter, which will focus on recent developments concerning thionin genes and their potential role in plant defense mechanisms

The thionins: a protein family that includes purothionins, viscotoxins and crambins

Almost half a century ago, a crystalline protein material was obtained from lipid extracts of wheat endosperm and designated "purothionin" (Trvpwo, wheat; 9 e i w v , sulphur) on account of its high sulphur content (Balls et al., 1942a,b). This material, which was thought to be the oxidized form of a powerful oxidation-reduction system, was found to have baetericidal and fungicidal properties (Stuart and Harris, 1942), to inhibit fermentation of wheat mashes (Balls and Harris, 1944), and to be toxic to laboratory animáis (Coulson et al., 1942)

Analysis of POSSUM score and postoperative morbidity in patients with rectal cancer undergoing surgery

The Physiological and Operative Severity Score for the enUmeration of Mortality and morbidity (POSSUM) and later modifications (P-POSSUM y CR-POSSUM) have been used to predict morbidity and mortality rates among patients with rectal cancer undergoing surgery. These calculations need some adjustment, however. The aim of this study was to assess the applicability of POSSUM to a group of patients with rectal cancer undergoing surgery, analysing surgical morbidity by means of several variables. METHODS: between January 1995 and December 2004, 273 consecutive patients underwent surgery for rectal cancer. Information was gathered about the patients, tumour and therapy. To assess the prediction capacity of POSSUM, subgroups for analysis were created according to variables related to operative morbidity and mortality. RESULTS: The global morbidity rate was 23.6% (31.2% predicted by POSSUM). The mortality rate was 0.7% (6.64, 1.95 and 2.08 predicted by POSSUM, P-POSSUM and CR-POSSUM respectively). POSSUM predictions may be more accurate for patients younger than 51 years, older than 70 years, with low anaesthetic risk (ASA I/II), DUKES stage C and D, surgery duration of less than 180 minutes and for those receiving neoadjuvant therapy. CONCLUSION: POSSUM is a good instrument to make results between different institutions and publication comparable. We found prediction errors for some variables related to morbidity. Modifications of surgical variables and specifications for neoadjuvant therapy as well as physiological variables including life style may improve future prediction of surgical risk. More research is needed to identify further potential risk factors for surgical complications

Analysis of Early Postoperative Morbidity Among Patients with Rectal Cancer Treated with and without Neoadjuvant Chemoradiotherapy

Background: The impact of neoadjuvant treatment and their subsequent early complications in the treatment of rectal cancer has not been adequately assessed. The aim of this prospective study was to evaluate early postoperative morbidity and mortality among patients with rectal cancer treated with adjuvant radiotherapy and chemotherapy followed by surgery, compared with patients treated with surgery alone. We also identified independent risk factors associated with early major complications. Methods: Between 1995 and 2004, 273 consecutive patients underwent treatment for rectal cancer. A total of 170 patients (group A) received preoperative radiotherapy with a total of 45–50.4 Gy (180 cGy per day) and 5-fluorouracil-based chemotherapy, followed by surgery; 103 patients (group B) were treated with surgery alone. Dependent variables related to patients, treatment, radiotherapy, and tumor were analyzed. Results: Both groups were similar with regard to age, sex, body mass index, American Society of Anesthesiologists (ASA) score, and tumor location but not for ileostomy (27% in group A vs. 6.8% in group B). The number of complications was similar in both groups (43.1% in group A vs. 44.6% in group B). No differences in wound infection (8.2% vs. 7.8%), intraabdominal abscess (4.7% vs. 4.9%), anastomotic dehiscence (4.2% vs. 3.8%), postoperative hemorrhage (3.5% vs. 3.9%), urinary complications (6.5% vs. 4.9%), paralytic ileus (8.9% vs. 9.7%), or general complications (7.1% vs. 9.6%) were found. The global mortality in the first 30 days after surgery was .7%. An ASA score of III–IV and surgery duration longer than 3 hours were identified as independent prognostic factors for early complications. Conclusions: Preoperative chemoradiation in patients with rectal cancer treated with surgery is not associated with a higher incidence of early postoperative complications. The patient~s preoperative clinical condition and lengthy surgery time are prognostic factors for early complications