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luis medina

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Dr. Nafiz Imtiaz Bin Hamid

Islamic University of Technology

Kansas State University

University of Tehran

University of Adelaide

Rob S E A N Wilson

University of California, Santa Cruz

Ayşe Elitok Kesici

Oakland University

Jose Wendell Capili

University of the Philippines

Visvesvaraya Technological University

Enrique E . Sánchez-Ruiz

Universidad de Guadalajara

Richard Crawford

The University of Texas at Austin

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Papers by luis medina

Single port radical prostatectomy: current status

Journal of Robotic Surgery, 2016

The aim of this study is to analyze the current literature on single port radical prostatectomy (... more The aim of this study is to analyze the current literature on single port radical prostatectomy (LESS-RP). Single port radical prostatectomy laparoendoscopic (LESS-RP) has established itself as a challenge for urological community, starting with the proposal of different approaches: extraperitoneal, transperitoneal and transvesical, initially described for laparoscopy and then laparoscopy robot-assisted. In order to improve the LESS-RP, new instruments, optical devices, trocars and retraction mechanisms have been developed. Advantages and disadvantages of LESS-RP are controversial, while some claim that it is a non-trustable approach, regarding the low cases number and technical difficulties, others acclaim that despite this facts some advantages have been shown and that previous described difficulties are being overcome, proving this is novel proposal of robotics platform, the Da Vinci SP, integrating the system into ''Y''. The LESS-RP approach gives us a new horizon and opens the door for rapid standardization of this technique. The few studies and short series available can be result of a low interest in the application of LESS-RP in prostate, probably because of the technical complexity that it requires. The new robotic platform, the da Vinci SP, shows that it is clear that the long awaited evolution of robotic technologies for laparoscopy has begun, and we must not lose this momentum.

Extremal algebraic connectivities of certain caterpillar classes and symmetric caterpillars

The Electronic Journal of Linear Algebra, 2010

A caterpillar is a tree in which the removal of all pendant vertices makes it a path. Let d ≥ 3 a... more A caterpillar is a tree in which the removal of all pendant vertices makes it a path. Let d ≥ 3 and n ≥ 6 be given. Let P d-1 be the path of d -1 vertices and Sp be the star of p + 1 vertices. Let p = [p 1 , p 2 , ..., p d-1 ] such that p 1 ≥ 1, p 2 ≥ 1, ..., p d-1 ≥ 1. Let C (p) be the caterpillar obtained from the stars Sp 1 , Sp 2 , ..., Sp d-1 and the path P d-1 by identifying the root of Sp i with the i-vertex of P d-1 . Let n > 2 (d -1) be given. Let In this paper, the caterpillars in C and in S having the maximum and the minimum algebraic connectivity are found. Moreover, the algebraic connectivity of a caterpillar in S as the smallest eigenvalue of a 2 × 2 -block tridiagonal matrix of order 2s × 2s if d = 2s + 1 or d = 2s + 2 is characterized.

Groundwater Vulnerability Assesment using two first level models - DRASTIC and Attenuation Factor

DESCRIPTION Two first level models (DRASTIC and AF) were used to assess Groundwater vulnerability... more

Sutura y anudado laparoscópico asistido por robot: estudio comparativo de la curva de aprendizaje

Vitae

Objetivo: Comparar la curva de aprendizaje de sutura y anudado intracorpóreo en cirugía laparoscó... more Objetivo: Comparar la curva de aprendizaje de sutura y anudado intracorpóreo en cirugía laparoscópica convencional y asistida por Robot. Método: Estudio prospectivo donde se evaluaron cinco individuos en laparoscopia convencional y asistida por robot para la realización de sutura y anudado intracorpóreo en modelo inanimado, valorados según la escala de GOALS y el tiempo requerido para realizar la tarea. Resultados: Se obtuvieron diferencias estadísticamente significativas en relación al tiempo y al puntaje obtenido en la escala de GOALS en laparoscopia asistida por robot sobre la laparoscopia convencional. Conclusión: Las prácticas de tareas laparoscópicas complejas asistidas por robot mejoran el desempeño y acortan la curva de aprendizaje en sujetos sin experiencia previa en laparoscopia avanzada.

Examining the role of Stress events and Depressive Symptoms on Birth Outcomes in a Sample of Chilean Low-Income Pregnant females

Preterm delivery is considered to be the leading cause of perinatal morbidity and mortality world... more Preterm delivery is considered to be the leading cause of perinatal morbidity and mortality worldwide. The determinants of this condition are several, however, researchers have discussed the role that psychosocial factors may have. Among these, , maternal tress and depression have been described as factors that influence birth outcomes, in particular premature birth, among females (e.g. Ritter et al., 2000; Rich-Edwards & Grizzard, 2005). We conducted a prospective study with a sample of 734 Chilean non-smokers females participated. We examined if numbers of stressors (PRAMS) to which these females were exposed and levels of depressive symptomatology (CES-D) measured during the first visit (week 12th) predicted premature birth (births before 35 weeks), controlling for other predictors of premature birth. Of the 734 females who participated, only 34 gave birth before 37 weeks. Our findings suggest that stress events but not depressive symptoms predicts premature birth , even when we ...

Evaluación del efecto antagonista de un consorcio bacteriano sobre Rhizoctonia solani Kühn en cultivos de arroz

Revista Latinoamericana de Biotecnología Ambiental y Algal, 2015

Resumen Rhizoctonia solani Kühn es un hongo fitopatógeno que ataca cultivos de arroz provocando d... more Resumen Rhizoctonia solani Kühn es un hongo fitopatógeno que ataca cultivos de arroz provocando disminución en el rendimiento de sus cosechas. Este trabajo evaluó el comportamiento de un consorcio bacteriano denominado “Lp” como agente biocontrolador del hongo fitopatógeno. Se determinó el efecto antifúngico de Lp frente a R. solani en cultivos duales in vitro; obteniéndose un 62 ± 1% de inhibición de crecimiento del hongo en medio Agar Papa Dextrosa y 58,0 ± 0,5% en agar nutritivo. El efecto antagónico estuvo relacionado a una actividad proteolítica extracelular presentes en sobrenadantes libres de células obtenidos de Lp, lo cual se determinó por zimografía. En pruebas de germinación en condiciones de laboratorio, la aplicación de Lp estimuló el crecimiento de plántulas de arroz. Estudios de campo preliminares indican un incremento de 44% en la producción de grano de arroz en cultivos tratados con Lp. Estos resultados demuestran que este consorcio bacteriano puede ser empleado com...

V8-12 Malfunction of Linear Cutting Stapler in Kidney Surgery

The Journal of Urology, 2015

INTRODUCTION AND OBJECTIVES: Numerous techniques exist for hilar control during laparoscopic and ... more INTRODUCTION AND OBJECTIVES: Numerous techniques exist for hilar control during laparoscopic and robotic nephrectomy. These include locking polymer clips, titanium clips, and individual or en bloc staple ligation. Staplers are most commonly employed for renal vein division and control. Stapling has proven safe, reproducible, rapid, and secure. Nevertheless, various types of stapler malfunction have been reported in the MAUDE (Manufacturer and User Device Experience) database with a failure incidence of 0.003%. Urologists must be acutely aware of these rare but potentially devastating scenarios. This video summarizes and illustrates various malfunction scenarios, and their proper management. METHODS: This video is a multicenter cases collection including 6 videos which exemplify linear cutting stapler failure on both the artery, and vein. Both inciting factors, and techniques for the surgeon to extricate themselves from these terrifying scenarios are depicted. The authors collected their experiences to offer recommendations, technical maneuvers and tips, both to prevent and solve these problems. RESULTS: There are two mechanism of action, depending on the brand and stapling mechanism. Some simultaneously staple and cut, others make a complete staple line, followed by cutting. We only present malfunction that occur with the second mechanism. Failures depicted include complete vein or artery transection, cutting failure with incomplete staple line, failure to release from tissue, staple line over a previous clip, as well as an unspecified stapler malfunction. CONCLUSIONS: Staplers are frequently used in urologic surgery, however the incidence of malfunction is quite low, so low that a resident may never see a staple malfunction during training. This educational video was therefore made to demonstrate the spectrum of potential types of device malfunctions. We hope that our recommendations serve as a teaching tool to minimize the risk of stapler misuse, and to deal with these dangerous complications.

A Comparative Study of Varroa Jacobsoni Reproduction in Worker Cells of Honey Bees (Apis Mellifera) in England and Africanized Bees in Yucatan, Mexico

Experimental and Applied Acarology, 1999

The aim of this study was to investigate an underlying mechanism of the apparent tolerance of Afr... more The aim of this study was to investigate an underlying mechanism of the apparent tolerance of Africanized honey bees (AHB) to Varroa jacobsoni mites in Mexico. This was achieved by conducting the first detailed study into the mites' reproductive biology in AHB worker cells. The data was then compared directly with a similar study previously carried out on European honey

Comparing data on the reproduction of Varroa destructor

Genetics and molecular research : GMR, Jan 31, 2003

Varroa destructor reproductive success is considered an important character for determining the r... more Varroa destructor reproductive success is considered an important character for determining the resistance of honey bees to this mite parasite. However, most of the published data are not comparable due to the different methods of ascertaining and reporting reproduction. A recently published technique that involves reconstructing mite families in older worker brood gives repeatable and reliable parameters. This methodology was used to compare various categories of reproduction of approximately 1,000 V. destructor females in each of three studies on Africanized bees in Brazil and Mexico and European bees in England. The most objective and useful measure was the determination of the number of viable females per female that had invaded the worker brood in singly infested cells, which was denominated the "effective reproduction rate". Viable females are those that can reach the adult stage and have a mate available. The effective reproduction rate in worker brood was 0.64, 0.7...

Hybridization Between European and Africanized Honey Bees in the Neotropical Yucatan Peninsula

Science, 1991

directly from the United States in the form of queen breeding stock, mostly consisting of the eas... more directly from the United States in the form of queen breeding stock, mostly consisting of the east-European subspecies A. m. caucasica and A. m. ligustica . Fifty years later, a prosperous beekeeping industry had developed in this region of Mexico, with In contrast to other parts of Mexico, the European honey bees, Apis mellifera L., were not imported into Yucatan until the early 1900s. These bees were introduced

The reaction between spodumene and tachyhydrite

Metallurgical Transactions B, 1988

The reaction between spodumene (Li20 9 A1203 9 4SIO2) and tachyhydrite (CaC12 9 2MgCI2 9 12H20) a... more The reaction between spodumene (Li20 9 A1203 9 4SIO2) and tachyhydrite (CaC12 9 2MgCI2 9 12H20) at temperatures above 1270 K, when the spodumene has transformed from the unreactive a-form to the fl-form, was studied varying the reaction temperature and the relative proportions of the two minerals in the reaction mixtures. Mass balances as well as X-ray diffraction to identify the reaction products indicate that the reactions that occur are 1. a decomposition of the tachyhydrite, losing at first some of its water of crystallization, followed by MgC12 hydrolyzing to MgO; 2. a transformation of the a-spodumene into fl-spodumene; and 3. a reaction between the fl-spodumene, MgO produced from tachyhydrite, and CaCI2 of the tachyhydrite according to the equation: Li20" AI20 3 9 4SIO2 + CaC12 + 8MgO = 2LiC1 + CaO. MgO. SiO2 + 3SiO2"2MgO + A1203"MgO. X-ray diffraction confirmed the presence of all the phases in the products except the phase containing alumina. Considerations of the quaternary phase diagram AI203-SiO2-MgO-CaO show that the phases indicated as reaction products are the ones expected under equilibrium conditions at the reaction temperature. Calculated standard free energy change (AG ~ of the suggested reaction is -211926 Joules at 1423 K, indicating that under standard conditions the reaction is possible.

Tight bounds on the algebraic connectivity of Bethe trees

Linear Algebra and its Applications, 2006

A rooted Bethe tree B d,k is an unweighted rooted tree of k levels in which the vertex root has d... more A rooted Bethe tree B d,k is an unweighted rooted tree of k levels in which the vertex root has degree d, the vertices in level 2 to level (k -1) have degree (d + 1) and the vertices in level k have degree 1 (pendant vertices). In this paper, we derive tight upper and lower bounds on the algebraic connectivity of (1) a Bethe tree B d,k , and (2) a tree B d,k 1 ,k 2 obtained by the union of two Bethe trees B d,k 1 and B d,k 2 having in common the vertex root. A useful tool in our study is the Sherman-Morrison formula.

On the algebraic connectivity of some caterpillars: A sharp upper bound and a total ordering

Linear Algebra and its Applications, 2010

A caterpillar is a tree in which the removal of all pendant vertices makes it a path. Let d 3 and... more A caterpillar is a tree in which the removal of all pendant vertices makes it a path. Let d 3 and n > 2(d -1) be given. Let p = [p 1 , p 2 , . . . , p d-1 ] with p 1 1, p 2 1, . . . , p d-1 1. Let C(p) be the caterpillar obtained from the stars S p 1 , S p 2 , . . . , S p d-1 and the path P d-1 by identifying the root of S p i with the i-vertex of P d-1 . Let We prove that the algebraic connectivity of C(p) ∈ C is bounded above by is the unique caterpillar in C attaining the upper bound and that if d is odd then the upper bound cannot be achieved. Finally, for 1 k d-1 2 , we give a total ordering by algebraic connectivity on C k = {C (1, . . . , 1, p k , 1, . . . , 1, p d-k , 1, . . . , 1) ∈ C : p k p d-k } .

Synthesis of glycerol-derived diallyl spiroorthocarbonates and the study of their antishrinking properties in acrylic dental resins

Journal of Materials Science: Materials in Medicine, 2013

In this work was evaluated the efficiency of an antishrinkage additive in a dental resin. This ad... more In this work was evaluated the efficiency of an antishrinkage additive in a dental resin. This additive was a mixture 1:1 of five and six-membered ring spiroorthocarbonates functionalized with allylic groups (SOC DA). The aim of this study was to reduce the shrinkage of a typical dental resin composed of a blend of the dimethacrylates, Glycerolate bi- ethyl, 2-methyl prop-2-enoate, (UDMA)/triethyleneglycol dimethacrylate (TEGDMA) in a 50:30.20 molar ratio, and silicon dioxide as filler. SOC DA was added at 5, 10 and 20 mol% to the already mentioned formulation. It was found that the addition of 20 mol% of SOC DA decreased 53 % the shrinkage of the cured composite material, in comparison with a formulation where it was not added the antishrinkage additive. Besides, the kinetics of photopolymerization determined by Real-Time infrared spectroscopy, demonstrated that the addition of increasing concentration of SOC DA improved the conversion of double bonds of dimethacrylates. Additionally, the presence of SOC DA at 10 % mol, helped to increase the flexural strength and the compressive strength of the composite, as a consequence of the augment of the crosslink density, induced by the ring opening polymerization of SOC DA.

Lys3-Bombesin Conjugated to99mTc-Labelled Gold Nanoparticles for In Vivo Gastrin Releasing Peptide-Receptor Imaging

Journal of Biomedical Nanotechnology, 2010

The gastrin releasing peptide-receptor (GRP-r) is over-expressed in breast and prostate cancer an... more The gastrin releasing peptide-receptor (GRP-r) is over-expressed in breast and prostate cancer and lymph node metastases. Lys 3 -bombesin is a peptide that binds with high affinity to GRP-r. The aim of this research was to prepare a multifunctional system of technetium-99m labelled gold nanoparticles conjugated to Lys 3 -bombesin/HYNIC-GGC and to evaluate its biological behaviour as a potential radiopharmaceutical for in vivo GRP-r imaging. Methods: Lys 3 -bombesin and hydrazinonicotinamide-Gly-Gly-Cys-NH 2 (HYNIC-GGC) peptides were conjugated to gold nanoparticles (AuNP, 20 nm) to prepare a multifunctional system of HYNIC-GGC-AuNP-Lys 3 -bombesin by means of spontaneous reaction of the thiol (Cys) present in HYNIC-GGC sequence and the amine of Lys 3 -bombesin. The nanoconjugate was characterized by transmission electron microscopy (TEM), IR, UV-Vis, Raman, and X-ray photoelectron spectroscopy (XPS). Technetium-99m labelling through the HYNIC-GGC ligand was carried out using EDDA/tricine as coligands and SnCl 2 as reducing agent with further size exclusion chromatography purification. Radiochemical purity was determined by size exclusion HPLC and ITLC-SG analyses. In vitro binding studies were carried out in human prostate cancer PC-3 cells (GRP-r positive cells). Biodistribution studies were accomplished in athymic mice with PC-3 induced tumours and images obtained using a micro-SPECT/CT system. Results: TEM and spectroscopy techniques demonstrated that AuNPs were functionalized with HYNIC-GGC-NH 2 and Lys 3 -bombesin through interactions with thiol groups of Cysteine and the N-terminal and -amine of Lysine respectively. Radio-chromatograms showed radiochemical purity higher than 95%. 99m Tc-EDDA/HYNIC-GGC-AuNP-Lys 3 -bombesin ( 99m Tc-AuNP-Lys 3 -bombesin) showed specific recognition for GRP-r over-expressed in PC-3 cells. After administration of 99m Tc-AuNP-Lys 3 -bombesin in mice the pancreas-to-blood ratio was 36 at 1 h demonstrating ability to target in vivo GRP receptor-bearing cells. In vivo micro-SPECT/CT images in mice showed an evident tumour uptake (6.39 ± 0.83% IA/g at 1 h). Conclusions: This study demonstrated that the 99m Tc-AuNP-Lys 3 -bombesin multifunctional system shows specific recognition for GRP-r and suitable properties to be used as a molecular imaging agent.

Synthesis and spectroscopic characterisation of (E)-2-(2-(9-(4-(1H-1,2,4-triazol-1-yl)butyl)-9H-carbazol-3-yl)vinyl)-3-ethylbenzo[d]thiazol-3-ium, a new ligand and potential DNA intercalator

Chemical Papers, 2013

Three new compounds based on carbazole planar skeleton were synthesised. Among them there is a ne... more Three new compounds based on carbazole planar skeleton were synthesised. Among them there is a new ligand and a potential DNA intercalator which contains a benzothiazolium moiety connected to the carbazole ring by a vinyl bridge. The absorption and emission spectral properties of this new ligand have been studied by spectroscopic methods.

Process viscometry of complex fluids and suspensions with helical ribbon agitators

The Canadian Journal of Chemical Engineering, 1998

The viscosity of highly inelastic shear thinning fluids and aqueous suspensions of kaolin clay pa... more The viscosity of highly inelastic shear thinning fluids and aqueous suspensions of kaolin clay particles has been investigated using a helical ribbon impeller fitted to a rheometer. Viscosity data for the single phase non‐Newtonian fluids adequately processed with a generalized Reynolds number based on the impeller tip speed are shown to superimpose very well to the results obtained with a cone and plate rheometer. In the case of the two‐phase system, it is shown that the data treatment for single phase system can be extended. The helical ribbon impeller yields more stable viscosity values than with the traditional geometries and no spurious flow phenomena (i.e., sedimentation, slip at the wall, etc.) was observed, making this system a superior device for suspension rheology over cone and plate and Couette flow rheometers.

Quorum quenching analysis in Pseudomonas aeruginosa and Escherichia coli: network topology and inhibition mechanism effect on the optimized inhibitor dose

Bioprocess and Biosystems Engineering, 2008

The discovery of quorum sensing as a mechanism for regulating specific phenotypes in bacteria bas... more The discovery of quorum sensing as a mechanism for regulating specific phenotypes in bacteria based on population density has conveyed attention to find molecules capable of interfering quorum sensing networks (QSN) in a process coined quorum quenching. Here, we examined the dynamics of Escherichia coli AI-2 and Pseudomonas aeruginosa QSN exposed to signal degraders or competitors for binding transcriptional regulators. Stability analysis was performed for E. coli and P. aeruginosa finding no multistability in E. coli. However, our model allowed to discern that quenchers influence P. aeruginosa QSN multistability by reducing the interval of the amount of molecules of the extracellular signal that originate several steady states. We proposed a simulated annealing algorithm to optimize the quencher dose based on stochastic kinetics. E. coli QSN requires around 640 while P. aeruginosa QSN needs 253 quencher molecules per microorganism. This dose was found to be negatively influenced by the quencher-signal affinity.

Reproduction of Varroa destructor in worker brood of Africanized honey bees (Apis mellifera)

… and Applied Acarology, 2002

Reproduction and population growth of Varroa destructor was studied in ten naturally infested, Af... more Reproduction and population growth of Varroa destructor was studied in ten naturally infested, Africanized honey bee (AHB) (Apis mellifera) colonies in Yucatan, Mexico. Between February 1997 and January 1998 monthly records of the amount of pollen, honey, sealed worker and drone brood were recorded. In addition, mite infestation levels of adult bees and worker brood and the fecundity of the mites reproducing in worker cells were determined. The mean number of sealed worker brood cells (10,070 ± 1,790) remained fairly constant over the experimental period in each colony. However, the presence and amount of sealed drone brood was very variable. One colony had drone brood for 10 months and another for only 1 month. Both the mean infestation level of worker brood (18.1 ± 8.4%) and adult bees (3.5 ± 1.3%) remained fairly constant over the study period and did not increase rapidly as is normally observed in European honey bees. In fact, the estimated mean number of mites fell from 3,500 in February 1997 to 2,380 in January 1998. In May 2000 the mean mite population in the study colonies was still only 1,821 mites. The fertility level of mites in this study was much higher (83-96%) than in AHB in Brazil (25-57%), and similar to that found in EHB (76-94%). Mite fertility remained high throughout the entire study and was not influenced by the amount of pollen, honey or worker brood in the colonies.

671 Abnormal ductus venosus velocimetry in fetuses with an increased impedance in the umbilical artery: An independent risk factor for fetal and neonatal death

American Journal of Obstetrics and Gynecology, 2001

OBJECTIVE: Measurement of the Middle Cerebral Artery Peak Systolic Velocity (MCA-PSV) in the fetu... more OBJECTIVE: Measurement of the Middle Cerebral Artery Peak Systolic Velocity (MCA-PSV) in the fetus has been shown to predict fetal anemia in pregnancies at risk because of red blood cell alloimmunization and decrease the need for invasive procedures in such pregnancies. The objective of this investigation was to study the reproducibility of MCA-PSV measm'ements in two different institutions. STUDY DESIGN: This study was performed on 25 normal fetuses. In each tetus, PSV was assessed at 3 different locations of the MCA proximal to the transducer: A) 2 mm after its origin from the internal carotid artery; B) in its mid-length between origin and division; C) 2 mm dose to its division. PSV was also assessed in the contralateral MCA 2 mm after its origin. With each measurement, care was taken to ensure that the ultrasound beam was parallel to the artery for its entire length. The reliability of an angle corrector was also assessed. The technical error of mea.surement and coefficient of variation (CV) were analyzed. The coefficient correlation (r) was also measured. A P < .05 indicated statistical significance. RESULTS: Gestational age at study entry ranged from 14 to 36 weeks (Median = 23.6 weeks). The proximal MCA 2 nun after its origin from the internal carotid artery (A) had the best intra-(mean 3.77%; SD: 0.899; Min 2.81%; Max: 4.64%; r: 0.99) and interobsmwer variability in both institutions (4.03%, r: 0.98; and 5.48%, r: 0.98, respectively) (P< .05)i No difference in the assessment of the MCA-PSV was noted when different equipment were evaluated (CV = 4.03%; r: 0.98). CONCLUSION: Our data confirm that fetal MCA-PSV is optimally measured in the proximal MCA 2ram after its origin t-urn the internal carotid artery. Given the importance of clinical decision based on this measurement, each sonographer and sonologist interested in the nmasurement of the MCA-PSV should test his/her intra-and inter-observer variability.

Single port radical prostatectomy: current status

Journal of Robotic Surgery, 2016

The aim of this study is to analyze the current literature on single port radical prostatectomy (... more The aim of this study is to analyze the current literature on single port radical prostatectomy (LESS-RP). Single port radical prostatectomy laparoendoscopic (LESS-RP) has established itself as a challenge for urological community, starting with the proposal of different approaches: extraperitoneal, transperitoneal and transvesical, initially described for laparoscopy and then laparoscopy robot-assisted. In order to improve the LESS-RP, new instruments, optical devices, trocars and retraction mechanisms have been developed. Advantages and disadvantages of LESS-RP are controversial, while some claim that it is a non-trustable approach, regarding the low cases number and technical difficulties, others acclaim that despite this facts some advantages have been shown and that previous described difficulties are being overcome, proving this is novel proposal of robotics platform, the Da Vinci SP, integrating the system into ''Y''. The LESS-RP approach gives us a new horizon and opens the door for rapid standardization of this technique. The few studies and short series available can be result of a low interest in the application of LESS-RP in prostate, probably because of the technical complexity that it requires. The new robotic platform, the da Vinci SP, shows that it is clear that the long awaited evolution of robotic technologies for laparoscopy has begun, and we must not lose this momentum.

Extremal algebraic connectivities of certain caterpillar classes and symmetric caterpillars

The Electronic Journal of Linear Algebra, 2010

A caterpillar is a tree in which the removal of all pendant vertices makes it a path. Let d ≥ 3 a... more A caterpillar is a tree in which the removal of all pendant vertices makes it a path. Let d ≥ 3 and n ≥ 6 be given. Let P d-1 be the path of d -1 vertices and Sp be the star of p + 1 vertices. Let p = [p 1 , p 2 , ..., p d-1 ] such that p 1 ≥ 1, p 2 ≥ 1, ..., p d-1 ≥ 1. Let C (p) be the caterpillar obtained from the stars Sp 1 , Sp 2 , ..., Sp d-1 and the path P d-1 by identifying the root of Sp i with the i-vertex of P d-1 . Let n > 2 (d -1) be given. Let In this paper, the caterpillars in C and in S having the maximum and the minimum algebraic connectivity are found. Moreover, the algebraic connectivity of a caterpillar in S as the smallest eigenvalue of a 2 × 2 -block tridiagonal matrix of order 2s × 2s if d = 2s + 1 or d = 2s + 2 is characterized.

Groundwater Vulnerability Assesment using two first level models - DRASTIC and Attenuation Factor

DESCRIPTION Two first level models (DRASTIC and AF) were used to assess Groundwater vulnerability... more

Sutura y anudado laparoscópico asistido por robot: estudio comparativo de la curva de aprendizaje

Vitae

Objetivo: Comparar la curva de aprendizaje de sutura y anudado intracorpóreo en cirugía laparoscó... more Objetivo: Comparar la curva de aprendizaje de sutura y anudado intracorpóreo en cirugía laparoscópica convencional y asistida por Robot. Método: Estudio prospectivo donde se evaluaron cinco individuos en laparoscopia convencional y asistida por robot para la realización de sutura y anudado intracorpóreo en modelo inanimado, valorados según la escala de GOALS y el tiempo requerido para realizar la tarea. Resultados: Se obtuvieron diferencias estadísticamente significativas en relación al tiempo y al puntaje obtenido en la escala de GOALS en laparoscopia asistida por robot sobre la laparoscopia convencional. Conclusión: Las prácticas de tareas laparoscópicas complejas asistidas por robot mejoran el desempeño y acortan la curva de aprendizaje en sujetos sin experiencia previa en laparoscopia avanzada.

Examining the role of Stress events and Depressive Symptoms on Birth Outcomes in a Sample of Chilean Low-Income Pregnant females

Preterm delivery is considered to be the leading cause of perinatal morbidity and mortality world... more Preterm delivery is considered to be the leading cause of perinatal morbidity and mortality worldwide. The determinants of this condition are several, however, researchers have discussed the role that psychosocial factors may have. Among these, , maternal tress and depression have been described as factors that influence birth outcomes, in particular premature birth, among females (e.g. Ritter et al., 2000; Rich-Edwards & Grizzard, 2005). We conducted a prospective study with a sample of 734 Chilean non-smokers females participated. We examined if numbers of stressors (PRAMS) to which these females were exposed and levels of depressive symptomatology (CES-D) measured during the first visit (week 12th) predicted premature birth (births before 35 weeks), controlling for other predictors of premature birth. Of the 734 females who participated, only 34 gave birth before 37 weeks. Our findings suggest that stress events but not depressive symptoms predicts premature birth , even when we ...

Evaluación del efecto antagonista de un consorcio bacteriano sobre Rhizoctonia solani Kühn en cultivos de arroz

Revista Latinoamericana de Biotecnología Ambiental y Algal, 2015

Resumen Rhizoctonia solani Kühn es un hongo fitopatógeno que ataca cultivos de arroz provocando d... more Resumen Rhizoctonia solani Kühn es un hongo fitopatógeno que ataca cultivos de arroz provocando disminución en el rendimiento de sus cosechas. Este trabajo evaluó el comportamiento de un consorcio bacteriano denominado “Lp” como agente biocontrolador del hongo fitopatógeno. Se determinó el efecto antifúngico de Lp frente a R. solani en cultivos duales in vitro; obteniéndose un 62 ± 1% de inhibición de crecimiento del hongo en medio Agar Papa Dextrosa y 58,0 ± 0,5% en agar nutritivo. El efecto antagónico estuvo relacionado a una actividad proteolítica extracelular presentes en sobrenadantes libres de células obtenidos de Lp, lo cual se determinó por zimografía. En pruebas de germinación en condiciones de laboratorio, la aplicación de Lp estimuló el crecimiento de plántulas de arroz. Estudios de campo preliminares indican un incremento de 44% en la producción de grano de arroz en cultivos tratados con Lp. Estos resultados demuestran que este consorcio bacteriano puede ser empleado com...

V8-12 Malfunction of Linear Cutting Stapler in Kidney Surgery

The Journal of Urology, 2015

INTRODUCTION AND OBJECTIVES: Numerous techniques exist for hilar control during laparoscopic and ... more INTRODUCTION AND OBJECTIVES: Numerous techniques exist for hilar control during laparoscopic and robotic nephrectomy. These include locking polymer clips, titanium clips, and individual or en bloc staple ligation. Staplers are most commonly employed for renal vein division and control. Stapling has proven safe, reproducible, rapid, and secure. Nevertheless, various types of stapler malfunction have been reported in the MAUDE (Manufacturer and User Device Experience) database with a failure incidence of 0.003%. Urologists must be acutely aware of these rare but potentially devastating scenarios. This video summarizes and illustrates various malfunction scenarios, and their proper management. METHODS: This video is a multicenter cases collection including 6 videos which exemplify linear cutting stapler failure on both the artery, and vein. Both inciting factors, and techniques for the surgeon to extricate themselves from these terrifying scenarios are depicted. The authors collected their experiences to offer recommendations, technical maneuvers and tips, both to prevent and solve these problems. RESULTS: There are two mechanism of action, depending on the brand and stapling mechanism. Some simultaneously staple and cut, others make a complete staple line, followed by cutting. We only present malfunction that occur with the second mechanism. Failures depicted include complete vein or artery transection, cutting failure with incomplete staple line, failure to release from tissue, staple line over a previous clip, as well as an unspecified stapler malfunction. CONCLUSIONS: Staplers are frequently used in urologic surgery, however the incidence of malfunction is quite low, so low that a resident may never see a staple malfunction during training. This educational video was therefore made to demonstrate the spectrum of potential types of device malfunctions. We hope that our recommendations serve as a teaching tool to minimize the risk of stapler misuse, and to deal with these dangerous complications.

A Comparative Study of Varroa Jacobsoni Reproduction in Worker Cells of Honey Bees (Apis Mellifera) in England and Africanized Bees in Yucatan, Mexico

Experimental and Applied Acarology, 1999

The aim of this study was to investigate an underlying mechanism of the apparent tolerance of Afr... more The aim of this study was to investigate an underlying mechanism of the apparent tolerance of Africanized honey bees (AHB) to Varroa jacobsoni mites in Mexico. This was achieved by conducting the first detailed study into the mites' reproductive biology in AHB worker cells. The data was then compared directly with a similar study previously carried out on European honey

Comparing data on the reproduction of Varroa destructor

Genetics and molecular research : GMR, Jan 31, 2003

Varroa destructor reproductive success is considered an important character for determining the r... more Varroa destructor reproductive success is considered an important character for determining the resistance of honey bees to this mite parasite. However, most of the published data are not comparable due to the different methods of ascertaining and reporting reproduction. A recently published technique that involves reconstructing mite families in older worker brood gives repeatable and reliable parameters. This methodology was used to compare various categories of reproduction of approximately 1,000 V. destructor females in each of three studies on Africanized bees in Brazil and Mexico and European bees in England. The most objective and useful measure was the determination of the number of viable females per female that had invaded the worker brood in singly infested cells, which was denominated the "effective reproduction rate". Viable females are those that can reach the adult stage and have a mate available. The effective reproduction rate in worker brood was 0.64, 0.7...

Hybridization Between European and Africanized Honey Bees in the Neotropical Yucatan Peninsula

Science, 1991

directly from the United States in the form of queen breeding stock, mostly consisting of the eas... more directly from the United States in the form of queen breeding stock, mostly consisting of the east-European subspecies A. m. caucasica and A. m. ligustica . Fifty years later, a prosperous beekeeping industry had developed in this region of Mexico, with In contrast to other parts of Mexico, the European honey bees, Apis mellifera L., were not imported into Yucatan until the early 1900s. These bees were introduced

The reaction between spodumene and tachyhydrite

Metallurgical Transactions B, 1988

The reaction between spodumene (Li20 9 A1203 9 4SIO2) and tachyhydrite (CaC12 9 2MgCI2 9 12H20) a... more The reaction between spodumene (Li20 9 A1203 9 4SIO2) and tachyhydrite (CaC12 9 2MgCI2 9 12H20) at temperatures above 1270 K, when the spodumene has transformed from the unreactive a-form to the fl-form, was studied varying the reaction temperature and the relative proportions of the two minerals in the reaction mixtures. Mass balances as well as X-ray diffraction to identify the reaction products indicate that the reactions that occur are 1. a decomposition of the tachyhydrite, losing at first some of its water of crystallization, followed by MgC12 hydrolyzing to MgO; 2. a transformation of the a-spodumene into fl-spodumene; and 3. a reaction between the fl-spodumene, MgO produced from tachyhydrite, and CaCI2 of the tachyhydrite according to the equation: Li20" AI20 3 9 4SIO2 + CaC12 + 8MgO = 2LiC1 + CaO. MgO. SiO2 + 3SiO2"2MgO + A1203"MgO. X-ray diffraction confirmed the presence of all the phases in the products except the phase containing alumina. Considerations of the quaternary phase diagram AI203-SiO2-MgO-CaO show that the phases indicated as reaction products are the ones expected under equilibrium conditions at the reaction temperature. Calculated standard free energy change (AG ~ of the suggested reaction is -211926 Joules at 1423 K, indicating that under standard conditions the reaction is possible.

Tight bounds on the algebraic connectivity of Bethe trees

Linear Algebra and its Applications, 2006

A rooted Bethe tree B d,k is an unweighted rooted tree of k levels in which the vertex root has d... more A rooted Bethe tree B d,k is an unweighted rooted tree of k levels in which the vertex root has degree d, the vertices in level 2 to level (k -1) have degree (d + 1) and the vertices in level k have degree 1 (pendant vertices). In this paper, we derive tight upper and lower bounds on the algebraic connectivity of (1) a Bethe tree B d,k , and (2) a tree B d,k 1 ,k 2 obtained by the union of two Bethe trees B d,k 1 and B d,k 2 having in common the vertex root. A useful tool in our study is the Sherman-Morrison formula.

On the algebraic connectivity of some caterpillars: A sharp upper bound and a total ordering

Linear Algebra and its Applications, 2010

A caterpillar is a tree in which the removal of all pendant vertices makes it a path. Let d 3 and... more A caterpillar is a tree in which the removal of all pendant vertices makes it a path. Let d 3 and n > 2(d -1) be given. Let p = [p 1 , p 2 , . . . , p d-1 ] with p 1 1, p 2 1, . . . , p d-1 1. Let C(p) be the caterpillar obtained from the stars S p 1 , S p 2 , . . . , S p d-1 and the path P d-1 by identifying the root of S p i with the i-vertex of P d-1 . Let We prove that the algebraic connectivity of C(p) ∈ C is bounded above by is the unique caterpillar in C attaining the upper bound and that if d is odd then the upper bound cannot be achieved. Finally, for 1 k d-1 2 , we give a total ordering by algebraic connectivity on C k = {C (1, . . . , 1, p k , 1, . . . , 1, p d-k , 1, . . . , 1) ∈ C : p k p d-k } .

Synthesis of glycerol-derived diallyl spiroorthocarbonates and the study of their antishrinking properties in acrylic dental resins

Journal of Materials Science: Materials in Medicine, 2013

In this work was evaluated the efficiency of an antishrinkage additive in a dental resin. This ad... more In this work was evaluated the efficiency of an antishrinkage additive in a dental resin. This additive was a mixture 1:1 of five and six-membered ring spiroorthocarbonates functionalized with allylic groups (SOC DA). The aim of this study was to reduce the shrinkage of a typical dental resin composed of a blend of the dimethacrylates, Glycerolate bi- ethyl, 2-methyl prop-2-enoate, (UDMA)/triethyleneglycol dimethacrylate (TEGDMA) in a 50:30.20 molar ratio, and silicon dioxide as filler. SOC DA was added at 5, 10 and 20 mol% to the already mentioned formulation. It was found that the addition of 20 mol% of SOC DA decreased 53 % the shrinkage of the cured composite material, in comparison with a formulation where it was not added the antishrinkage additive. Besides, the kinetics of photopolymerization determined by Real-Time infrared spectroscopy, demonstrated that the addition of increasing concentration of SOC DA improved the conversion of double bonds of dimethacrylates. Additionally, the presence of SOC DA at 10 % mol, helped to increase the flexural strength and the compressive strength of the composite, as a consequence of the augment of the crosslink density, induced by the ring opening polymerization of SOC DA.

Lys3-Bombesin Conjugated to99mTc-Labelled Gold Nanoparticles for In Vivo Gastrin Releasing Peptide-Receptor Imaging

Journal of Biomedical Nanotechnology, 2010

The gastrin releasing peptide-receptor (GRP-r) is over-expressed in breast and prostate cancer an... more The gastrin releasing peptide-receptor (GRP-r) is over-expressed in breast and prostate cancer and lymph node metastases. Lys 3 -bombesin is a peptide that binds with high affinity to GRP-r. The aim of this research was to prepare a multifunctional system of technetium-99m labelled gold nanoparticles conjugated to Lys 3 -bombesin/HYNIC-GGC and to evaluate its biological behaviour as a potential radiopharmaceutical for in vivo GRP-r imaging. Methods: Lys 3 -bombesin and hydrazinonicotinamide-Gly-Gly-Cys-NH 2 (HYNIC-GGC) peptides were conjugated to gold nanoparticles (AuNP, 20 nm) to prepare a multifunctional system of HYNIC-GGC-AuNP-Lys 3 -bombesin by means of spontaneous reaction of the thiol (Cys) present in HYNIC-GGC sequence and the amine of Lys 3 -bombesin. The nanoconjugate was characterized by transmission electron microscopy (TEM), IR, UV-Vis, Raman, and X-ray photoelectron spectroscopy (XPS). Technetium-99m labelling through the HYNIC-GGC ligand was carried out using EDDA/tricine as coligands and SnCl 2 as reducing agent with further size exclusion chromatography purification. Radiochemical purity was determined by size exclusion HPLC and ITLC-SG analyses. In vitro binding studies were carried out in human prostate cancer PC-3 cells (GRP-r positive cells). Biodistribution studies were accomplished in athymic mice with PC-3 induced tumours and images obtained using a micro-SPECT/CT system. Results: TEM and spectroscopy techniques demonstrated that AuNPs were functionalized with HYNIC-GGC-NH 2 and Lys 3 -bombesin through interactions with thiol groups of Cysteine and the N-terminal and -amine of Lysine respectively. Radio-chromatograms showed radiochemical purity higher than 95%. 99m Tc-EDDA/HYNIC-GGC-AuNP-Lys 3 -bombesin ( 99m Tc-AuNP-Lys 3 -bombesin) showed specific recognition for GRP-r over-expressed in PC-3 cells. After administration of 99m Tc-AuNP-Lys 3 -bombesin in mice the pancreas-to-blood ratio was 36 at 1 h demonstrating ability to target in vivo GRP receptor-bearing cells. In vivo micro-SPECT/CT images in mice showed an evident tumour uptake (6.39 ± 0.83% IA/g at 1 h). Conclusions: This study demonstrated that the 99m Tc-AuNP-Lys 3 -bombesin multifunctional system shows specific recognition for GRP-r and suitable properties to be used as a molecular imaging agent.

Synthesis and spectroscopic characterisation of (E)-2-(2-(9-(4-(1H-1,2,4-triazol-1-yl)butyl)-9H-carbazol-3-yl)vinyl)-3-ethylbenzo[d]thiazol-3-ium, a new ligand and potential DNA intercalator

Chemical Papers, 2013

Three new compounds based on carbazole planar skeleton were synthesised. Among them there is a ne... more Three new compounds based on carbazole planar skeleton were synthesised. Among them there is a new ligand and a potential DNA intercalator which contains a benzothiazolium moiety connected to the carbazole ring by a vinyl bridge. The absorption and emission spectral properties of this new ligand have been studied by spectroscopic methods.

Process viscometry of complex fluids and suspensions with helical ribbon agitators

The Canadian Journal of Chemical Engineering, 1998

The viscosity of highly inelastic shear thinning fluids and aqueous suspensions of kaolin clay pa... more The viscosity of highly inelastic shear thinning fluids and aqueous suspensions of kaolin clay particles has been investigated using a helical ribbon impeller fitted to a rheometer. Viscosity data for the single phase non‐Newtonian fluids adequately processed with a generalized Reynolds number based on the impeller tip speed are shown to superimpose very well to the results obtained with a cone and plate rheometer. In the case of the two‐phase system, it is shown that the data treatment for single phase system can be extended. The helical ribbon impeller yields more stable viscosity values than with the traditional geometries and no spurious flow phenomena (i.e., sedimentation, slip at the wall, etc.) was observed, making this system a superior device for suspension rheology over cone and plate and Couette flow rheometers.

Quorum quenching analysis in Pseudomonas aeruginosa and Escherichia coli: network topology and inhibition mechanism effect on the optimized inhibitor dose

Bioprocess and Biosystems Engineering, 2008

The discovery of quorum sensing as a mechanism for regulating specific phenotypes in bacteria bas... more The discovery of quorum sensing as a mechanism for regulating specific phenotypes in bacteria based on population density has conveyed attention to find molecules capable of interfering quorum sensing networks (QSN) in a process coined quorum quenching. Here, we examined the dynamics of Escherichia coli AI-2 and Pseudomonas aeruginosa QSN exposed to signal degraders or competitors for binding transcriptional regulators. Stability analysis was performed for E. coli and P. aeruginosa finding no multistability in E. coli. However, our model allowed to discern that quenchers influence P. aeruginosa QSN multistability by reducing the interval of the amount of molecules of the extracellular signal that originate several steady states. We proposed a simulated annealing algorithm to optimize the quencher dose based on stochastic kinetics. E. coli QSN requires around 640 while P. aeruginosa QSN needs 253 quencher molecules per microorganism. This dose was found to be negatively influenced by the quencher-signal affinity.

Reproduction of Varroa destructor in worker brood of Africanized honey bees (Apis mellifera)

… and Applied Acarology, 2002

Reproduction and population growth of Varroa destructor was studied in ten naturally infested, Af... more Reproduction and population growth of Varroa destructor was studied in ten naturally infested, Africanized honey bee (AHB) (Apis mellifera) colonies in Yucatan, Mexico. Between February 1997 and January 1998 monthly records of the amount of pollen, honey, sealed worker and drone brood were recorded. In addition, mite infestation levels of adult bees and worker brood and the fecundity of the mites reproducing in worker cells were determined. The mean number of sealed worker brood cells (10,070 ± 1,790) remained fairly constant over the experimental period in each colony. However, the presence and amount of sealed drone brood was very variable. One colony had drone brood for 10 months and another for only 1 month. Both the mean infestation level of worker brood (18.1 ± 8.4%) and adult bees (3.5 ± 1.3%) remained fairly constant over the study period and did not increase rapidly as is normally observed in European honey bees. In fact, the estimated mean number of mites fell from 3,500 in February 1997 to 2,380 in January 1998. In May 2000 the mean mite population in the study colonies was still only 1,821 mites. The fertility level of mites in this study was much higher (83-96%) than in AHB in Brazil (25-57%), and similar to that found in EHB (76-94%). Mite fertility remained high throughout the entire study and was not influenced by the amount of pollen, honey or worker brood in the colonies.

671 Abnormal ductus venosus velocimetry in fetuses with an increased impedance in the umbilical artery: An independent risk factor for fetal and neonatal death

American Journal of Obstetrics and Gynecology, 2001

OBJECTIVE: Measurement of the Middle Cerebral Artery Peak Systolic Velocity (MCA-PSV) in the fetu... more OBJECTIVE: Measurement of the Middle Cerebral Artery Peak Systolic Velocity (MCA-PSV) in the fetus has been shown to predict fetal anemia in pregnancies at risk because of red blood cell alloimmunization and decrease the need for invasive procedures in such pregnancies. The objective of this investigation was to study the reproducibility of MCA-PSV measm'ements in two different institutions. STUDY DESIGN: This study was performed on 25 normal fetuses. In each tetus, PSV was assessed at 3 different locations of the MCA proximal to the transducer: A) 2 mm after its origin from the internal carotid artery; B) in its mid-length between origin and division; C) 2 mm dose to its division. PSV was also assessed in the contralateral MCA 2 mm after its origin. With each measurement, care was taken to ensure that the ultrasound beam was parallel to the artery for its entire length. The reliability of an angle corrector was also assessed. The technical error of mea.surement and coefficient of variation (CV) were analyzed. The coefficient correlation (r) was also measured. A P < .05 indicated statistical significance. RESULTS: Gestational age at study entry ranged from 14 to 36 weeks (Median = 23.6 weeks). The proximal MCA 2 nun after its origin from the internal carotid artery (A) had the best intra-(mean 3.77%; SD: 0.899; Min 2.81%; Max: 4.64%; r: 0.99) and interobsmwer variability in both institutions (4.03%, r: 0.98; and 5.48%, r: 0.98, respectively) (P< .05)i No difference in the assessment of the MCA-PSV was noted when different equipment were evaluated (CV = 4.03%; r: 0.98). CONCLUSION: Our data confirm that fetal MCA-PSV is optimally measured in the proximal MCA 2ram after its origin t-urn the internal carotid artery. Given the importance of clinical decision based on this measurement, each sonographer and sonologist interested in the nmasurement of the MCA-PSV should test his/her intra-and inter-observer variability.