Male tilapia production techniques: A mini-review

Tilapia culture has been growing over the past decades as an excellent source of high-quality protein. Some of the Tilapia´s advantages are the ability to breed and produce new generations rapidly, tolerate shallow and turbid waters, resist a high level of disease and be flexible for culture under many different farming systems. These characteristics are the main reasons for its commercial success. However, one of them contributes to the major drawback of pond culture: the high level of uncontrolled reproduction that may occur in grow-out ponds. Uncontrolled reproduction yields to stunted growth and unmar-ketable fish due to offspring competing with the initial stock for food, besides other problems like less dissolved oxygen, greater release of ammonia and feces, heterogeneous sizes and overpopulation stress. Monosex production has been preferred in order to deal with these issues. Males are preferred because they grow almost twice as fast as the females. This paper reviews monosex male production techniques and their results, comprising environment manipulation, hybridization, sex reversal and genetic manipulation. The choice of a particular technique would depend on the legislation of each country. This review’s should help to select the appropriate technique depending on the market target and the commercial technology available.Keywords: Monosex production, hybridization, sex reversal, environmental and genetic sex determinationAfrican Journal of Biotechnology Vol. 12(36), pp. 5496-550

EL DISEÑO ESTRATÉGICO APLICADO A LA GESTIÓN DE RESIDUOS EN GRANJAS CUNÍCOLAS

En este artículo se presenta la aplicación del diseño estratégico como catalizador de alternativas de solución a la gestión de residuos en la cunicultura. Primero, se describen los problemas, a los que se enfrentan los productores con respecto a la separación y recolección los residuos; por medio de una comparación entre granjas semitecnificadas y tecnificadas en el estado de Querétaro y las instalaciones del Centro Nacional de Cunicultura ubicado en la ciudad de Irapuato, Gto. Después, se aplican las diferentes etapas de la metodología del Pensamiento de Diseño (Design thinking) con el fin de analizar instalaciones, sistemas operativos y trabajadores involucrados en la gestión de residuos y diseñar un sistema que facilite esta actividad. La investigación concluye que la frecuencia de recolección y tiempo de exposición de los residuos dentro de las instalaciones son determinantes para la eficientizaciòn de la recolección de residuos. Además se identificó al diseño como factor para mejorar la usabilidad de los sistemas propuestos y con ello reducir el tiempo invertido diariamente por parte de los trabajadores, y mitigar las concentraciones Gases de Efecto Invernadero (GEI) asociados a la exposición de excretas. Lo que deriva en la mejora de la inocuidad del ambiente, salud de los conejor y aumento de la calidad de la producción cunícola

A Potential Alternative for Agar in In Vitro Culture Media Based on Hydrocolloids Present in Nopal: General Structure and Mechanical Properties

In Vitro culture is a technique commonly used for plant research. Nevertheless, it is more expensive than traditional methods of production, due to the use of the culture medium gelling agent called agar. Recent studies have been searching for alternative substances in raw materials with the same characteristics but which can be extracted easier than agar. The dietary fiber of the nopal cactus (Opuntia) is a rich source of hydrocolloids (pectin and mucilage). These hydrocolloids have the ability to gel in combination with the indicated solution. In this chapter, we will focus on the study of the hydrocolloids from nopal cactus to replace agar partially and/or totally as a gelling agent using in vitro culture media benefiting from the molecular structure and mechanical properties of the compounds

Nitrogen determination on tomato (Lycopersicon esculentum Mill.) seedlings by color image analysis (RGB)

In order to investigate the effectiveness of a new method based on color image analysis and the Minolta SPAD-502 chlorophyll meter for the diagnosis of nitrogen deficiencies of tomato seedlings, a field experiment was conducted. In this study, five levels of nitrogen fertilization were established so as to induce nitrogen deficiencies in tomato seedlings. Thirty-five days after sowing, total nitrogen was evaluated by laboratory analysis. The chlorophyll index was determined using a SPAD-502 chlorophyll meter. Also, color images were taken with a digital camera; the color images were processed in MATLAB in order to determine the averages of the red color, green color and the blue color. The relationships between variables were analyzed by linear regressions and a one way analysis of variance (p < 0.01). Results showed that color image analysis correlated better with the status of plant nitrogen than the SPAD. From the color image analysis, the red and blue colors were more accurate predictors of nitrogen status on plants with R2 above 0.89. Color image analysis provides an accurate and quick way for nitrogen estimation and can contribute for early detection of nitrogen deficiency in tomato seedlings. The SPAD method is not a reliable way to estimate the nitrogen status on tomato seedlings.Keywords: Color image analysis (RGB), chlorophyll meter, nitrogen deficiencyAfrican Journal of Biotechnology Vol. 9(33), pp. 5326-5332, 16 August, 201

Long-Range Wireless Mesh Network for Weather Monitoring in Unfriendly Geographic Conditions

In this paper a long-range wireless mesh network system is presented. It consists of three main parts: Remote Terminal Units (RTUs), Base Terminal Units (BTUs) and a Central Server (CS). The RTUs share a wireless network transmitting in the industrial, scientific and medical applications ISM band, which reaches up to 64 Km in a single point-to-point communication. A BTU controls the traffic within the network and has as its main task interconnecting it to a Ku-band satellite link using an embedded microcontroller-based gateway. Collected data is stored in a CS and presented to the final user in a numerical and a graphical form in a web portal

Integración de biopolímeros en la industria textil

Para que el sector industrial pueda cumplir con la demanda del mercado es necesaria una sobreexplotación de fuentes naturales que causan problemas ecológicos en algunos casos irreversibles. Es por ello que se han buscado alternativas de materias primas que tenga la misma funcionalidad que un textil y que no dañen al planeta. En este artículo se expone que los biopolímeros pueden tener una gran ventaja para frenar estos problemas ecológicos. Entre estas fibras encontramos las que provienen de proteínas regeneradas, que son las que contiene base caseína, que al ser materiales biodegradables, amigables con el ambiente y con una estructura que se puede modificar, se pueden considerar como una alternativa factible para cumplir con los requerimientos de los usuarios sin dejar de lado el cuidado ambiental y el cumplimiento de la producción que se necesita para satisfacer la demanda de estos bienes

A Survey of Hybridisation Methods of GNSS and wireless LAN based Positioning System

Self-localisation has become a matter of course in our daily life. The emerging market of mobile devices still boosts the demand for seamless, ubiquitous positioning. The repertoire of sensors serviceable for localisation provided by current mobile devices is large; however the main positioning systems used today are based on wireless local area networks (WLAN), cellular networks and certainly global navigation satellite systems (GNSS). Because of the accuracy, the vast deployment and the channel characteristics, researchers have been focused on WLAN based positioning systems (WPS) in particular, to achieve seamless positioning. This paper reviews the latest data fusion approaches to seamless positioning by GNSS and WPS. In accordance to the level of data fusion, several approaches are categorised and briefly presented, differences in performance of these approaches are highlighted and future challenges identified.publishedVersionPeer reviewe

Dual-Phase Lock-In Amplifier Based on FPGA for Low-Frequencies Experiments

Photothermal techniques allow the detection of characteristics of material without invading it. Researchers have developed hardware for some specific Phase and Amplitude detection (Lock-In Function) applications, eliminating space and unnecessary electronic functions, among others. This work shows the development of a Digital Lock-In Amplifier based on a Field Programmable Gate Array (FPGA) for low-frequency applications. This system allows selecting and generating the appropriated frequency depending on the kind of experiment or material studied. The results show good frequency stability in the order of 1.0 × 10−9 Hz, which is considered good linearity and repeatability response for the most common Laboratory Amplitude and Phase Shift detection devices, with a low error and standard deviation