Extensões ao Projeto LVWNet: mobilidade, interação com equipamentos reais, comunicação direta, e registro dinâmico de nós

Due to the constantly increasing use of wireless networks in domestic, business and industrial environments, new challenges have emerged. The prototyping of new protocols in these environments is typically restricted to simulation environments, where there is the need of double implementation, one in the simulation environment where an initial proof of concept is performed and the other one in a real environment. Also, if real environments are used, it is not trivial to create a testbed for high density wireless networks given the need to use various real equipment as well as attenuators and power reducers to try to reduce the physical space required to create these laboratories. In this context, LVWNet (Linux Virtual Wireless Network) project was originally designed to create completely virtual testbeds for IEEE 802.11 networks on the Linux operating system. This paper aims to extend the current project LVWNet, adding to it the features like the ability to interact with real wireless hardware, provides a initial mobility ability using the positioning of the nodes in a space coordinates environment based on meters, with loss calculations due to attenuation in free space, enables some scalability increase by creating an own protocol that allows the communication between nodes without an intermediate host and dynamic registration of nodes, allowing new nodes to be inserted into in already in operation network

Extração e caracterização de amido de jacatupé (Pachyrhizus ahipa)

O gênero Pachyrhizus tem sido estudado como fonte de matéria-prima amilácea devido ao considerável teor de amido nas raízes de suas espécies. Neste trabalho objetivou-se caracterizar raízes de P. ahipa, processar em laboratório para a extração do amido e analisá-lo quanto à composição centesimal, teor de amilose, formato e tamanho de grânulos em microscópio eletrônico de varredura e viscosidade das pastas (RVA). As raízes de P. ahipa apresentaram 18% de massa seca sendo 7,68% amido. O rendimento obtido de amido foi baixo (4,28%), apontando para a necessidade de estudos que melhorem o processo de extração. O produto obtido apresentou 12,3% de umidade, 84% de amido com 13% de amilose e baixos teores de outros componentes (base úmida). A análise em microscópio eletrônico de varredura mostrou grânulos de amido de formas circular e poligonal, com tamanho variando entre 10 e 25mm. O perfil de viscosidade apresentado por este amido mostrou baixa temperatura de pasta (56ºC) e pico de viscosidade a 272 RVU, estando este último valor próximo ao observado para amido de mandioca, sob as mesmas condições. O amido de P. ahipa apresentou ainda, baixa estabilidade da pasta a quente e tendência à retrogradação com o resfriamento.

Selection of X chromosome of buffaloes sperm with Percoll gradients

The aim of the present study was to evaluate the selection of X chromosome of buffaloes sperm with Percoll gradients. The stock solution of Percoll was prepared in the proportion of 1:11 (1 part of Percoll:11 parts of a solution containing KCl 1M, NaH(2)PO(4) 0.1M, NaCl 1.5M and sodium HEPES 23.8 g/ml). In order to prepare 9 different gradients were added to the stocked Percoll the A solution (glicine-yolk extender) in the following proportions: 90, 80, 72, 65, 57, 49, 34 and 25%. A sample of 0.7 ml of the fresh semen was deposited at 2 ml of Percoll 80% for the sperm wash. The precipitate was put in tube with 0.7 ml of each gradient. Then, the precipitated was washed in TES solution by centrifugation (500xg for 10 minutes), and collected again and diluted in TES solution to be freeze. The presence of the F body in the spermatozoa was observed in 58.7 +/- 5.4% of the control group and in 41.2 +/- 5.4% of the treated group (p<0.01). This result showed an increment of 17.55 of male sperm in the Percoll's group. The reduction of the centrifugation force did not improve the percentage of X sperm.

Morphological and functional characteristics of chilled semen obtained from domestic feline epididymides (Felis catus)

The objective of this study was to determine morphological and functional characteristics of semen retrieved from the feline epididymis before and after cooling. Sixteen adult male cats were orchiectomized. The distal portion of the epididymis and proximal part of the deferent ducts were dissected and squeezed to obtain their content. After centrifugation, the supernatant was removed, sperm were resuspended in a 0.9 mL Tris-fructose-citric acid extender containing 20% egg yolk, aliquoted into three 0.3 mL samples, placed in a refrigerator (4.8 degrees C) and cooled (0.5 degrees C/min). Semen evaluations were performed on four occassions: immediately after epididymal sperm retrieval (TO), and at 24 h (T-1), 48 h (T-2) and 72 h (T-3) after cooling. on each occasion, progressive motility, vigor and sperm morphology were determined. Mean motility and vigor decreased (P < 0.05) between each successive examination. Although the majority of sperm cell damage occurred within the first 24 h, there was a decrease (P < 0.05) in mean percentage of morphologically normal sperm between To and each evaluated time (T-1, T-2, T-3) after cooling, due to an increase in coiled and bent sperm tails. Further studies are needed to evaluate the effects of cooling on the fertilizing capacity of cat epididymal spermatozoa in assisted reproduction programs. (c) 2006 Elsevier B.V. All rights reserved.

Influence of semen storage and cryoprotectant on post-thaw viability and fertility of stallion spermatozoa

The aim of the current study was to verify that stallion, spermatoza could be cooled for 24 hours and then frozen. In experiment I, one ejaculate from each of 13 stallions was used. Semen was collected and split into two parts; one part immediately frozen using standard cryo-preservation techniques and the other diluted, stored in an Equitainer for 24 hours, and then frozen. In experiment II, one ejaculate from each of 12 stallions was collected, diluted with Botu-Semen, and split into two parts: one cooled in an Equitainer and the other in Max-Semen Express without prior centrifugation. After 24 hours of cooling, the samples were centrifuged to remove seminal plasma and concentrate the sperm, and resuspended in Botu-Crio (R) extender containing on e of three cryoprotectant treatments (1% glycerol + 4% dimethylformamide, 1% glycerol + 4% dimethylacetamide and 1% glycerol + 4% methylformamide), maintained at 5 degrees C for 20 minutes, then frozen in nitrogen vapour. No difference was observed between the two cooling systems. The association of 1% glycerol and 4% methylformamide provided the best post-thaw progressive motility. For experiment III, two stallions were used for a fertility trial. Forty three inseminations were performed using 22 mares. No differences were seen in semen parameters and pregnancy rates when comparing the two freezing protocols (conventional and cooled/frozen). Pregnancy rates for conventional and cooled/frozen semen were, respectively, 72.7% and 82.3% (stallion A), and 40.0% and 50.0% (stallion B). We concluded that cooling equine-semen for 24 hours before freezing while maintaining sperm viability and fertility is possible.

Semen cryopreservation protocols of Mangalarga Marchador stallions

The effect of the utilization of three semen protocols (Inra 82®, Merck Gema and Botu-crio®) and two filling techniques (0.25 and 0.50 mL straws) in Mangalarga Marchador stallions were studied in this experiment. Sperm parameters were assessed during processing and post-freezing. No interactions between the protocols and type of filling were observed, so they were assessed separately. Sperm parameters were not altered when the extender was added to the centrifugation; however, there was reduction of motility and strength when freezing extenders were added. The Botu-crio® protocol preserved the parameters of total and progressive sperm motility, smoothed path velocity (µm/s), straight line velocity (µm/s), track velocity (µm/s) and the average and fast spermatozoa percentage better than the others. No difference between the extenders for the percentage of sperm integrity was observed. There was no difference in the responses studied on the filling techniques. The stallions presented better freezing with the use of the Botu-crio® protocol. The best post-freezing viability results were found for semen frozen using the Botu-crio® protocol and there were no differences concerning the sperm quality comparing 0.25 and 0.50 mL straws.

Comparison of in vitro and in vivo fertilizing potential of bovine semen frozen in egg yolk or new lecithin based extenders

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Impact of 24-h Cooling Prior to Freezing on the Survival of Domestic Cat (Felis catus) Epididymal Sperm

The aim of this study was to investigate the impact of a 24-h cooling period prior to freezing on domestic cat epididymal sperm viability. Fifteen tomcats were submitted to routine orchiectomy and sperm samples were retrieved from both epididymides in a Tris-glucose-20% egg yolk extender. For each tomcat, the diluted sperm was split into two equal volumes and cooled to 5 degrees C at a rate of 0.5 degrees C/min; one sample for 60 min (control) and the other for 24 h (cooled). After the cooling period, samples from both groups were frozen using an identical freezing protocol. Sperm samples were evaluated in three different periods: immediately after harvesting, after cooling at 5 degrees C for 24 h (cooled group) and after freezing thawing of control and cooled groups. Evaluations consisted of sperm motility and progressive status, sperm morphology and plasma membrane integrity (PMI) using two fluorescent probes. After cooling for 24 h, a decrease (p < 0.05) in sperm motility, progressive status and PMI was observed when compared to sperm samples immediately after collection. Comparing the results obtained after thawing, no difference (p < 0.05) was found regarding sperm motility, progressive status, PMI and sperm morphology between control and cooled groups. The results from the present study show that cooling cat epididymal spermatozoa at 5 degrees C for 24 h prior to freezing does not lead to major damage of spermatozoa impairing the freeze-thaw process.

Fertilizing Capacity of Frozen Epididymal Sperm Collected from Dogs

The collection of epididymal sperm may be a valuable tool for canine reproduction especially since it can enable collection of cells after death of a valuable dog. The aim of the present study was to evaluate the viability of epididymal sperm after freeze-thawing. Epididymides were obtained from four adult dogs by elective orchiectomy. The caudal portion of the epididymides and part of the deferential ducts were squeezed by means of an anatomic clamp into a Petri dish containing either 0.9% saline solution (Group 1) or Ringer solution without lactate (Group 2). Samples were centrifuged at 800 x g for 10 min, the supernatant was removed and the pellet was diluted in one step with a Tris/citric acid/OEP (Orvus Es Paste) extender containing 7% glycerol and subjected to semen freezing. Oocytes were obtained from canine ovaries, after ovariohysterectomy. Only oocytes that were approximately 100 mu m in diameter, with a dark ooplasm surrounded by three-or four-well formed cumulus cell layers were used for sperm testing. Frozen semen samples were thawed in a water bath at 70 degrees C for 8 s and analysed at room temperature for sperm motility and velocity. Oocytes were incubated with spermatozoa in humidified atmosphere containing 5% CO(2) at 38 degrees C for 18 h. Morphological and functional characteristics of spermatozoa were similar in both groups. However, the percentage of sperm cells bound to oocytes was significantly higher in Group 2 than in Group 1. This result suggests that the Ringer solution without lactate was a more suitable medium for collecting epididymal canine sperm than 0.9% saline.

Cryopreservation and fertility of ejaculated and epididymal stallion sperm

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Lipid peroxidation and generation of hydrogen peroxide in frozen-thawed ram semen supplemented with catalase or Trolox

Semen manipulation and cryopreservation-thaw procedures may accelerate the generation of reactive oxygen species (ROS). Sperm exposure to large amounts of ROS has been shown to cause membrane lipid peroxidation and cellular injury to the sperm. The objective of this study was to overcome the ROS production in frozen-thawed ram semen by the addition of the antioxidants catalase or Trolox to semen following thawing. Frozen-thawed ram semen (100 x 10(6) sperm/straw) was supplemented with PBS (control group), 100 mu g/ml catalase, or 100 mu M Trolox/10(8) sperm (catalase and Trolox being dissolved in PBS) and incubated (37 degrees C) for 5 min. Under the experimental conditions used in this study, the catalase and Trolox antioxidants failed to protect the sperm from the spontaneous production of ROS. However, when lipid peroxidation was induced by iron (FeSO(4)), the addition of Trolox promoted a reduction (P < 0.05) in the formation of TBARS in the semen, compared to the control and catalase semen samples. The generation of TBARS and H(2)O(2) occurred in the extender alone, without the presence of sperm cells. In conclusion, the addition of Trolox to frozen-thawed ram semen could be beneficial as it decreases the production of TBARS when oxidative stress is induced. It is possible that a longer incubation period could lead to different results. The concentration of catalase also needs to be further evaluated. The extender could contribute to the oxidative stress of sperm, as it is a source of ROS during the cryopreservation of semen. (C) 2010 Elsevier B.V. All rights reserved.

Thermoresistance sperm tests are not predictive of potential fertility for cryopreserved bull semen

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Lipid peroxidation and generation of hydrogen peroxide in frozen-thawed ram semen cryopreserved in extenders with antioxidants

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Effect of refrigeration systems upon frozen bull sperm viability assessed by computer-assisted sperm analysis and fluorescent probes

Sperm cryopreservation success depends upon the maintenance of spermatozoa fertility potential. Sperm cells must preserve both integrity and functionality of several cell structures. The stabilization phase must allow the exit of water from the sperm cells via osmosis. This study aimed to compare the effect of refrigeration in the commercial refrigerator (CR) and the transport/refrigeration box (TRB) upon the viability of frozen bull sperm diluted in three different extenders (A, B and C). Ten Nellore bulls, Bos taurus indicus maintained in Artificial Insemination Center were used and the spermatozoa samples was assessed for Plasma Membrane Integrity and CASA evaluation. The stabilization phase (5 degrees C/4 hours) was performed in the CR as well as in the TRB, and then samples were exposed to nitrogen vapor during 20 minutes and then plunged into nitrogen. The statistical analysis was done using the variance analysis and the significance level was set at 5%. In the CR the post-thawing parameters for PM and ALH were higher (p < 0.05) in the extender A (glicine egg-yolk) and extender B (glicine egg-free) when compared with extender C (TRIS egg-yolk). As for BCF, STR and LIN, the parameters were higher (p < 0.05) in extender B than in C. Samples that were stabilized in the TRB presented higher post-thawing parameters (p < 0.05) for PM and LIN in extender A and extender B when compared with C. BCF and STR parameters were higher (p < 0.05) in extemder B when compared with C. Extender B samples had higher (p < 0.05) PMI when stabilized in CR. The findings in this experiment enable us to say that both CR and TRB were effective in keeping the viability of post-thawing bull semen.

Influence of Steroidal Anti-Inflammatory Drugs on Viability and Fertility of Equine Semen

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)