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J Rius

Publications and source records attributed to J Rius.

At least 19 recordsLinked to original sources
PubMed2004

New insights in the c(4 x 2) reconstruction of hexadecanethiol on Au(111) revealed by grazing incidence X-ray diffraction.

The c(4 x 2) structure of C16H33SH alkanethiol monolayers self-assembled on Au(111) has been studied by grazing incidence X-ray diffraction. This structure coexists on the surface with the (radical3x radical3)R30 degrees phase. The structural refinement of the c(4 x 2) phase has been accomplished by omitting the fractional order reflections common to both structures. The surface unit cell consists of four symmetry-independent molecules with atomic displacements related by couples, such that only two nonequivalent chains are present in the surface cell. The stability between neighbor chains is due to van der Waals interactions. The substrate plays an important and non-negligible role in the c(4 x 2) reconstruction. The lateral and normal substrate relaxations to the surface plane are small, and gold atom displacements are lower than 0.25 angstroms but contribute very strongly to the fractional order intensities. The molecular chains form a close packed structure tilted by 37 degrees from the surface normal with no indications of dimer formation between closest S atoms.

Gold↗
PubMed2003

Uterine sarcoma associated with tamoxifen use: case report.

A case of müllerian adenosarcoma with sarcomatous overgrowth in a postmenopausal 66-year-old female patient after adjuvant tamoxifen treatment for breast carcinoma is described. The patient was asymptomatic and the neoplasm was detected by pelvic sonography. The diagnosis was based on the histological findings after curettage and complementary total hysterectomy with bilateral salpingo-oophorectomy. The association of tamoxifen use and development of mesenchymal neoplasms is discussed.

Adenosarcoma↗
PubMed2003

A comparative analysis of the modification of sexual desire of users of oral hormonal contraceptives and intrauterine contraceptive devices.

OBJECTIVE: To compare the influence of oral hormonal contraceptives (OCs) and the use of intrauterine contraceptive devices (IUDs) on the modification of sexual desire. MATERIALS AND METHODS: A prospective observational study of 1073 women using OCs or an IUD at the Family Planning Center 'Marina Alta' in Alicante, Spain. In order to evaluate the relative risk regarding the decrease in libido attributed to each contraceptive method, a logistic regression analysis was undertaken which considered the factors of age adjustment, level of studies, family planning information, relationship with partner, age when sexual relationships were initiated, parity, contraceptive method previously used and the duration of use of the contraceptive method. RESULTS: No differences in the decrease of sexual desire were observed between the use of the OC and IUD (odds ratio (OR) 1.32; 95% confidence interval (CI) 0.70-2.49), yet differences were noted, however, in relation to age (OR 1.05; 95% CI 1.01-1.10). Although these differences were not statistically significant, a high level of awareness regarding family planning was shown to increase sexual desire when compared to a lower level of information on this subject (OR 0.64; 95% CI 0.41-1.01). Sexual desire was seen to decrease if the quality of the relationship with the partner was average (OR 2.24; 95% CI 1.36-3.69) or poor (OR 4.69; 95% CI 1.93-11.4). Nulliparous women showed a greater decrease in sexual desire in relation to women who had already given birth (OR 1.57; 95% CI 1.00-2.47). Sexual desire was greater if the contraceptive method had already been in use for 6-12 months (OR 0.41; 95% CI 0.17-0.98). CONCLUSIONS: Sexual desire does not vary in relation to the use of OCs or IUDs, yet it does decrease with age, in nulliparous women and in those with an average or poor relationship with their partner. Furthermore, sexual desire shows an increase between the first 6 and 12 months of contraceptive treatment.

Adolescent↗
PubMed2002

Geometry of the valence transition induced surface reconstruction of Sm(0001).

We present a structural determination of the surface reconstruction of the Sm(0001) surface using surface x-ray diffraction, scanning tunneling microscopy, and ab initio calculations. The reconstruction is associated with a large (22%) expansion of the atomic radius for the top monolayer surface Sm atoms. The mechanism driving the surface reconstruction in Sm is unique among all elements and is connected to the strong correlations of the 4f electrons in Sm and the intermediate valence observed in certain Sm compounds. The atoms constituting the top monolayer of Sm(0001) have vastly different chemical properties compared to the layer underneath and behave as if they were an adsorbate of a different chemical species.

Journal Article↗
PubMed2000

Incorporation of stable organic radicals of the tris(2,4, 6-trichlorophenyl)methyl radical series to pyrrole units as models for semiconducting polymers with high spin multiplicity. 1.

The condensation reactions between (4-amino-2,6-dichlorophenyl)bis(2, 4,6-trichlorophenyl)methyl radical and acetylacetone or 1, 4-bis(5-methyl-2-thienyl)-1,4-butanedione yield [2,6-dichloro-4-(2, 5-dimethyl-1-pyrrolyl)phenyl]bis(2,4,6-trichlorophenyl)methyl radical (3(*)()) and [2,6-dichloro-4-[2, 5-bis(5-methyl-2-thienyl)-1-pyrrolyl]phenyl]bis(2,4, 6-trichlorophenyl)methyl radical (4(*)()), respectively. EPR studies of both radicals 3(*)() and 4(*)() in CH(2)Cl(2) solution suggest a weak electron delocalization with coupling constant values of 1.25 and 1.30 G, respectively, with the six aromatic hydrogens. Their electrochemical behavior was analyzed by cyclic voltammetry. Both radicals show reversible reduction processes at E degrees = -0.69 V and -0.61 V versus SSCE, respectively, and anodic peak potentials at E(p)(a) = 1.10 and 0.72 V, respectively, versus SSCE at a scan rate (nu) of 200 mV s(-)(1), being reversible for radical 4(*)(). X-ray analysis of radical 3(*)() shows a high value (65 degrees ) of the dihedral angle between the 2,5-dimethylpyrrolidyl moiety and the phenyl ring. Smooth oxidation of radical 4(*)() in CH(2)Cl(2) containing trifluoroacetic acid gives an ionic diradical species with a weak electron interaction (|D/hc| = 0.0047 cm(-)(1)). A Curie plot of the Deltam(s)() = +/-2 signal intensity versus the inverse of the absolute temperature in the range between 4 and 70 K suggests a triplet or a nearly degenerate singlet-triplet ground state.

Journal Article↗
PubMed2000

Study of C60/Au(110)-p(6x5) reconstruction from In-plane X-Ray diffraction data

Fullerene molecules absorbed on the highly anisotropic Au(110)-p(1x2) surface induce an ordered p(6x5) superstructure that has been solved by applying the 2D "direct methods" difference sum function to the surface x-ray diffraction data set. We found that the C (60)-gold interface is structurally much more complex than the one previously suggested by scanning tunneling microscopy data [J. K. Gimzewski, S. Modesti, and R. R. Schlittler, Phys. Rev. Lett. 72, 1036 (1994)]. Indeed a large fraction of Au surface atoms are displaced from their original positions producing microscopic pits that may accommodate the fullerene molecules.

Journal Article↗
PubMed2000

Gracilis transposition in complicated perianal fistula and unhealed perineal wounds in Crohn's disease.

OBJECTIVE: To assess the efficacy of transposition of gracilis muscle in the treatment of chronic recurrent fistulas and unhealed perineal wounds after proctectomy in patients with Crohn's disease. DESIGN: Retrospective study. SETTING: Academic clinic, United States. SUBJECTS: 7 patients with Crohn's disease: 3 had unhealed perineal wounds and persistent sinuses; 2 had had several attempts to repair rectovaginal fistulas; 1 had a rectourethral fistula; and 1 a pouch vaginal fistula. INTERVENTION: Transposition of the gracilis muscle. MAIN OUTCOME MEASURE: Healing. RESULTS: Mean follow up was 18 months (range 3-30). All patients operated on for unhealed perineal wounds had healed completely within 3-6 months. The patients with a rectovaginal fistula and a rectourethral fistula had both healed by 1 month postoperatively. Two fistulas recurred, and the small pouch-vaginal fistula remained but was asymptomatic. CONCLUSIONS: Transposition of the gracilis is a viable option for the treatment of persistent sinus and unhealed perineal wound after proctectomy for Crohn's disease. It could also be an option before proctectomy for patients with other types of Crohn's-related or complicated fistulas for whom other treatments have failed. A larger series will be required before a definite conclusion can be drawn.

Adolescent↗
PubMed2000

Full instability behavior of N-dimensional dynamical systems with a one-directional nonlinear vector field

We show how certain N-dimensional dynamical systems are able to exploit the full instability capabilities of their fixed points to do Hopf bifurcations and how such a behavior produces complex time evolutions based on the nonlinear combination of the oscillation modes that emerged from these bifurcations. For really different oscillation frequencies, the evolutions describe robust wave form structures, usually periodic, in which self-similarity with respect to both the time scale and system dimension is clearly appreciated. For closer frequencies, the evolution signals usually appear irregular but are still based on the repetition of complex wave form structures. The study is developed by considering vector fields with a scalar-valued nonlinear function of a single variable that is a linear combination of the N dynamical variables. In this case, the linear stability analysis can be used to design N-dimensional systems in which the fixed points of a saddle-node pair experience up to N-1 Hopf bifurcations with preselected oscillation frequencies. The secondary processes occurring in the phase region where the variety of limit cycles appear may be rather complex and difficult to characterize, but they produce the nonlinear mixing of oscillation modes with relatively generic features.

Journal Article↗
PubMed1997

A new probability distribution of the triplet from Patterson function arguments. V.

The physical basis of the conditional probability distributions of the quartet and of the triplet are investigated by means of the 'Patterson' and 'modulus' sum functions, respectively. From this study, a new conditional probability distribution of the triplet follows which has been tested on real data from three structures of different size. The empirically found distribution is compared with Cochran's closely related distribution.

Journal Article↗
PubMed1996

Stimulated gracilis neosphincter operation. Initial experience, pitfalls, and complications.

PURPOSE: The stimulated gracilis neosphincter is accepted as a viable option in select patients with fecal incontinence. The aim of this study was to review the initial problems and complications. METHODS: A prospective analysis of all patients who underwent this procedure was undertaken. Stage I consisted of the distal vascular delay of the muscle and creation of a temporary stoma. Stage II was the transposition of the muscle and implantation of the stimulator and electrodes. Low frequency electrical stimulation was applied to the muscle for 12 weeks, after which Stage III (stoma closure) was undertaken. RESULTS: From March 1993 to December 1995, 17 patients (9 females and 8 males) with a mean age of 42.2 (range, 19-72) years underwent the procedure. One patient died from pancreatitis and another from small-bowel adenocarcinoma, three and six months after the procedure, respectively. Two patients (one with Crohn's disease) required permanent stomas. One additional patient required a permanent stoma because of lead fibrosis. Other complications noted during ascent of the learning curve included seroma of the thigh incision, excoriation of the skin above the stimulator, fecal impaction, anal fissure, parastomal hernia, rotation of the stimulator, premature battery discharge, fracture of the lead, perineal skin irritation, perineal sepsis, rupture of the tendon, tendon erosion, muscle fatigue during programming sessions, and electrode displacement from the nerve or fibrosis around the nerve. However, ultimately after rectification of these problems, 13 of the 15 eligible patients had stoma reversal. Manometric results showed an average basal pressure of 43 mmHg and an average maximum squeeze pressure that increased from 36 mmHg before surgery to 145 mmHg by stimulation (P < 0.01). Based on objective functional questionnaires, 9 of 15 (60 percent) evaluable patients reported improvement in continence, social interactions, and quality of life. Three of these nine patients require daily use of enemas. CONCLUSION: Although the stimulated gracilis operation is a feasible procedure for selected patients with severe incontinence, the learning curve is steep. Although the ultimate outcome in a selected group of patients can be very gratifying, major technical modifications are required before use beyond a research protocol setting. Furthermore, patients must have the psychological strength, emotional commitment, and financial resources that may be necessary for multiple revisional surgeries or ultimate device failure.

Adult↗
PubMed1994

[Percutaneous endoscopic gastrostomy: study on 35 patients].

BACKGROUND: A review of the technique, indications, complications and follow up of percutaneous endoscopic gastrostomy (PEG) was performed. METHODS: Thirty-five patients in whom a PEG had been placed according to the Ponsky technique from 1991 to 1993 were analyzed 27 of whom had neurologic disease, 6 tumoral diseases and 2 other causes. RESULTS: PEG was carried out in 33 patients with no incidences while the technique could not be performed in 2 since the point could not be identified by transillumination in the gastric wall. No immediate complications were observed. Seven minor early complications were presented as wound infection with the cannula being withdrawn in only one case due to persistence of the infection. Five late complications were reported: 1 severe (gastrocholic fistula) and 4 minor (2 cannula obstructions, 1 displacement and 1 infection). Evolution was followed in 31 patients with the cannula being withdrawn in 4 (2 because of complications and in the other 2 on initiation of oral diet). The cannula was substituted at 120 and 360 days in 2 patients. Sixteen patients died, 5 during the first 30 days due to the primary disease, with only one case (aspirative pneumonia) being related to the PEG. The PEG continues functioning in 11 patients. CONCLUSIONS: Percutaneous endoscopic gastrostomy for feeding is a simple technique which may be carried out in most patients with scarce severe complications, allowing a good nutritional state and improving the quality of life of patients requiring prolonged enteral feeding.

Adult↗
PubMed1990

Clinical and electrophysiologic findings in acute ischemic intraHisian bundle-branch block.

Clinical and electrophysiologic features of acute ischemic right bundle-branch block (RBBB) that are reversible by His bundle pacing were analyzed in nine patients. All had large anterior myocardial infarctions (mean peak CK-MB = 185 +/- 71 IU/l), and six showed increased pulmonary capillary pressures. The RBBB occurred within 48 hours of infarction, and in six patients it was associated with left fascicular block. The HV intervals that were measured 1 to 4 days after infarction were normal in all patients. Progression to complete atrioventricular (AV) block occurred in three patients, and one patient required permanent cardiac pacing. Sustained ventricular tachycardia developed in two patients, and ventricular fibrillation developed in five. During a mean follow-up period of 26 months, four patients died (three of them suddenly). The RBBB disappeared in only one case. Acute ischemic intraHisian RBBB occurred in the setting of massive myocardial infarctions complicated by ventricular tachycardia or fibrillation and by a high mortality rate during the follow-up period. The RBBB rarely reverted spontaneously, and the His-Purkinje conduction time was frequently normal.

Bundle of His↗
PubMed1990

Circadian variations of electrical properties of the heart.

Cardiac refractoriness and electrical inducibility of supraventricular tachycardia (SVT) were assessed at intervals of 1 to 2 hours over a period of 22 hours in 38 patients (25 with paroxysmal SVT). Daily variability of effective refractory period (ERP) had a mean range of 35 +/- 14 mseconds for the atria, 79 +/- 65 mseconds for the AV node, 24 +/- 10 m seconds for the ventricles, 51 +/- 27 mseconds for the retrograde Kent bundle, and 35 +/- 17 mseconds for the antegrade Kent bundle. Between 11 PM and 8 AM there was a significant prolongation of the ERP of the atria (ANOVA, p less than 0.001), AV node (p = 0.002), right ventricle (p less than 0.001), and retrograde Kent bundle (p = 0.005), and a reduction in electrical induction of SVT from 75% to 42% (p less than 0.05) with respect to the first electrophysiologic study. This nocturnal prolongation was preceded by ERP shortening of all explored cardiac sites and by increased tachycardia inducibility between 8 and 10 PM. Six patients with dual AV nodal pathways showed a prolongation of the fast pathway ERP at midnight, whereas conduction through the slow pathway followed an unpredictable daily variability. These data indicate a circadian influence on refractoriness of normal cardiac tissues and accessory pathways that exerted a midnight protection against electrical inducibility of reciprocating tachycardia but a transient arrhythmia facilitation at the evening.

Adolescent↗
PubMed1988

Octapolar electrocatheter for His bundle recording and sequential bedside electrophysiologic testing.

To reduce the number of electrocatheters required for an electrophysiologic study and to facilitate prolonged monitoring of the electrical properties of the heart, an octapolar electrocatheter was designed and tested in 45 consecutive patients undergoing routine electrophysiologic studies. The electrocatheter introduced into the right ventricle served for: (a) right ventricular pacing; (b) recording of low lateral and low septal right atrial electrograms; (c) recording of the His bundle potential in 39 out of the 45 patients (86%); (d) 24-hour monitoring of the AV conduction intervals and refractory periods at the patients' bedsides. The octapolar electrocatheter reduced the number of probes required for studying the mechanisms of reciprocating tachycardia and allowed 24-hour bedside electrophysiologic monitoring.

Adult↗
PubMed1987

Daily variability of electrically induced reciprocating tachycardia in patients with atrioventricular accessory pathways.

Sequential bedside electrophysiologic testing was performed over 22 hours at intervals of 1 to 2 hours in 13 patients with left-sided Kent bundles to assess possible daily variations in the capacity to electrically induce reciprocating tachycardia. In all patients the tachycardia involved the accessory pathway in retrograde atrial activation. Between midnight and early morning the more relevant findings with respect to the first testing performed at midday were a significant prolongation of the effective refractory period of the atrial (from 212 +/- 22 msec to 229 +/- 22 msec; p less than 0.01), atrioventricular node (from 235 +/- 22 msec to 285 +/- 15 msec; p less than 0.005), right ventricle (from 209 +/- 15 msec to 221 +/- 12 msec; p less than 0.001), and retrograde Kent bundle (from 278 +/- 34 msec to 294 +/- 24 msec; p less than 0.01) and a reduction of the inducibility of tachycardia from both the coronary sinus from 90% to 50%; p less than 0.001) and the right ventricle from 80% to 15%; p less than 0.001). Thus our results indicate that there exists a nocturnal protection against electrical induction of reciprocating tachycardia that is associated with a prolongation of the atrial, atrioventricular nodal, ventricular, and Kent bundle refractoriness.

Adolescent↗