Galileo's Crucial Experiment: an Epistemological Analysis

En los Discorsi Galileo afirma haber realizado un experimento, cuyo resultado fue negativo, para determinar si la luz tarda tiempo en propagarse. En este trabajo analizo ese experimento como crucial entre las hipótesis rivales según las cuales la luz se propaga con velocidad infinita o con velocidad finita. Procuro determinar las hipótesis auxiliares y la carga teórica que presupone el diseño experimental. Argumento que las hipótesis presupuestas son razonables y que la carga teórica es muy baja. Sostengo que en principio es posible un experimento crucial exitoso, esto es, con resultado positivo, como el concebido por Galileo. Concluyo que la hipótesis de que la luz se propaga con velocidad finita no es refutable mediante un experimento de esta clase, por lo cual cualquier resultado negativo es compatible con ambas hipótesis rivales. Como consecuencia de ello, la hipótesis de que la luz, o cualquier otra interacción física, se propagan con velocidad infinita resulta inverificable.In his Discorsi, Galileo claims to have performed an experiment to determine whether light takes time in propagating from one place to another. In this paper I take that experiment as crucial between the rival hypotheses of finite and infinite speed of light. I contend that, in spite of Galileo's negative result, such a crucial experiment is possible, both in principle and in practice. I then argue that it employs reasonable auxiliary hypotheses. I conclude that a positive result in a Galileo-type experiment would refute the hypothesis of instantaneous propagation of light and verify the hypothesis of finite velocity. However, a negative result is always compatible with the two rivals, and consequently, the hypothesis of finite velocity is not refutable by any possible experience.Fil: Cassini, Alejandro Pablo F.. Universidad de Buenos Aires; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentin

Isolamento e caracterização de bactérias endofíticas não patogênicas em milho.

bitstream/item/58846/1/Pesq.And.-31-1.pd

Genetic diversity of indigenous common bean (Phaseolus vulgaris L.) rhizobia from the state of Minas Gerais, Brazil.

We characterized indigenous common bean rhizobia from five districts of the state of Minas Gerais, Brazil. The isolates were trapped by two common bean varieties, the Mineiro Precoce (Andean origin) and Ouro Negro (Mesoamerican origin). Analysis by BOX-P CR of selected isolates detected a high level of genetic diversity

Models without a Target

Se afirma con frecuencia que hay algunos modelos científicos que no poseen un target. En tal caso, no resulta claro cómo es posible el razonamiento surrogativo. En este artículo defiendo la tesis de que todos los modelos tienen un target. Argumento que los targets no deben identificarse con determinados fenómenos selectos, ni con porciones o aspectos selectos del mundo real. Intento mostrar que el target de cualquier modelo siempre es el producto de un complejo proceso de construcción, proceso que no puede explicarse solamente por medio de la abstracción a partir de los fenómenos. Concluyo que, aunque todos los modelos tienen un target, sus dominios de aplicación pueden cambiar o incluso ser vacíos.It is frequently acknowledged that some scientific models do not have a target. In that case, it is not clear how surrogative reasoning is possible. In this article, I contend that every model has a target. I argue that targets should not be identified with selected phenomena or with selected portions or aspects of the real world. I intend to show that the target of any model is always the outcome of a complex process of construction, a process that cannot be accounted for solely by means of abstraction from the phenomena. I conclude that although all models have a fixed target, their domain of application may change or even be empty.Fil: Cassini, Alejandro Pablo F.. Universidad de Buenos Aires. Facultad de Filosofía y Letras. Instituto de Filosofía "Dr. Alejandro Korn"; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentin

What an interpretation of quantum mechanics should be?

There are many so-called interpretations of quantum mechanics, but we presently do not have any clear-cut criteria to identify them. Usually, scientists do not distinguish the different interpretations of the standard quantum theory from its alternative or rival theories, although there is an established fact that there exist different – even non-empirically equivalent – quantum theories. In this article, I put forward some criteria to distinguish between formulations, interpretations, and alternatives to a given quantum theory. I then show that we have just some partial criteria to identify quantum theories and distinguish them from interpretations. According to such criteria, all interpretations of a given quantum theory must be empirically equivalent to it, otherwise, they are rival theories, and must not be logically equivalent to it, otherwise, they are different formulations of such theory. I conclude that interpreting a quantum theory cannot consist in providing a unique ontology for that theory because the same theory is compatible with many different ontologies.Fil: Cassini, Alejandro Pablo F.. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Universidad de Buenos Aires; Argentin

Evaluation of a candidate breast cancer associated SNP in ERCC4 as a risk modifier in BRCA1 and BRCA2 mutation carriers. Results from the Consortium of Investigators of Modifiers of BRCA1/BRCA2 (CIMBA)

Background: In this study we aimed to evaluate the role of a SNP in intron 1 of the ERCC4 gene (rs744154), previously reported to be associated with a reduced risk of breast cancer in the general population, as a breast cancer risk modifier in BRCA1 and BRCA2 mutation carriers. Methods: We have genotyped rs744154 in 9408 BRCA1 and 5632 BRCA2 mutation carriers from the Consortium of Investigators of Modifiers of BRCA1/2 (CIMBA) and assessed its association with breast cancer risk using a retrospective weighted cohort approach. Results: We found no evidence of association with breast cancer risk for BRCA1 (per-allele HR: 0.98, 95% CI: 0.93–1.04, P=0.5) or BRCA2 (per-allele HR: 0.97, 95% CI: 0.89–1.06, P=0.5) mutation carriers. Conclusion: This SNP is not a significant modifier of breast cancer risk for mutation carriers, though weak associations cannot be ruled out. A Osorio1, R L Milne2, G Pita3, P Peterlongo4,5, T Heikkinen6, J Simard7, G Chenevix-Trench8, A B Spurdle8, J Beesley8, X Chen8, S Healey8, KConFab9, S L Neuhausen10, Y C Ding10, F J Couch11,12, X Wang11, N Lindor13, S Manoukian4, M Barile14, A Viel15, L Tizzoni5,16, C I Szabo17, L Foretova18, M Zikan19, K Claes20, M H Greene21, P Mai21, G Rennert22, F Lejbkowicz22, O Barnett-Griness22, I L Andrulis23,24, H Ozcelik24, N Weerasooriya23, OCGN23, A-M Gerdes25, M Thomassen25, D G Cruger26, M A Caligo27, E Friedman28,29, B Kaufman28,29, Y Laitman28, S Cohen28, T Kontorovich28, R Gershoni-Baruch30, E Dagan31,32, H Jernström33, M S Askmalm34, B Arver35, B Malmer36, SWE-BRCA37, S M Domchek38, K L Nathanson38, J Brunet39, T Ramón y Cajal40, D Yannoukakos41, U Hamann42, HEBON37, F B L Hogervorst43, S Verhoef43, EB Gómez García44,45, J T Wijnen46,47, A van den Ouweland48, EMBRACE37, D F Easton49, S Peock49, M Cook49, C T Oliver49, D Frost49, C Luccarini50, D G Evans51, F Lalloo51, R Eeles52, G Pichert53, J Cook54, S Hodgson55, P J Morrison56, F Douglas57, A K Godwin58, GEMO59,60,61, O M Sinilnikova59,60, L Barjhoux59,60, D Stoppa-Lyonnet61, V Moncoutier61, S Giraud59, C Cassini62,63, L Olivier-Faivre62,63, F Révillion64, J-P Peyrat64, D Muller65, J-P Fricker65, H T Lynch66, E M John67, S Buys68, M Daly69, J L Hopper70, M B Terry71, A Miron72, Y Yassin72, D Goldgar73, Breast Cancer Family Registry37, C F Singer74, D Gschwantler-Kaulich74, G Pfeiler74, A-C Spiess74, Thomas v O Hansen75, O T Johannsson76, T Kirchhoff77, K Offit77, K Kosarin77, M Piedmonte78, G C Rodriguez79, K Wakeley80, J F Boggess81, J Basil82, P E Schwartz83, S V Blank84, A E Toland85, M Montagna86, C Casella87, E N Imyanitov88, A Allavena89, R K Schmutzler90, B Versmold90, C Engel91, A Meindl92, N Ditsch93, N Arnold94, D Niederacher95, H Deißler96, B Fiebig97, R Varon-Mateeva98, D Schaefer99, U G Froster100, T Caldes101, M de la Hoya101, L McGuffog49, A C Antoniou49, H Nevanlinna6, P Radice4,5 and J Benítez1,3 on behalf of CIMB

Solar Magnetism eXplorer (Solme X)

The magnetic field plays a pivotal role in many fields of Astrophysics. This is especially true for the physics of the solar atmosphere. Measuring the magnetic field in the upper solar atmosphere is crucial to understand the nature of the underlying physical processes that drive the violent dynamics of the solar corona-that can also affect life on Earth. SolmeX, a fully equipped solar space observatory for remote-sensing observations, will provide the first comprehensive measurements of the strength and direction of the magnetic field in the upper solar atmosphere. The mission consists of two spacecraft, one carrying the instruments, and another one in formation flight at a distance of about 200 m carrying the occulter to provide an artificial total solar eclipse. This will ensure high-quality coronagraphic observations above the solar limb. SolmeX integrates two spectro-polarimetric coronagraphs for off-limb observations, one in the EUV and one in the IR, and three instruments for observations on the disk. The latter comprises one imaging polarimeter in the EUV for coronal studies, a spectro-polarimeter in the EUV to investigate the low corona, and an imaging spectro-polarimeter in the UV for chromospheric studies. SOHO and other existing missions have investigated the emission of the upper atmosphere in detail (not considering polarization), and as this will be the case also for missions planned for the near future. Therefore it is timely that SolmeX provides the final piece of the observational quest by measuring the magnetic field in the upper atmosphere through polarimetric observation

Ciencia y seudociencia: ¿por qué todavía es importante distinguirlas?

¿Cómo se distingue la ciencia de la seudociencia? ¿Dónde debe trazarse la frontera? El problema dela demarcación está lejos de ser simple y todavía no tiene una solución general satisfactoria. El trabajo analiza diferentes criterios de demarcación y muestra que no resultan necesarios y/o suficientes para distinguir la ciencia de la seudociencia. Concluye que, no obstante, el problema de la demarcación tiene importancia social y educativa, por lo que no es posible prescindir de algún conjunto de criterios, aunque resulten parciales.Fil: Cassini, Alejandro Pablo F.. Universidad de Buenos Aires. Facultad de Filosofía y Letras. Instituto de Filosofía "Dr. Alejandro Korn"; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentin

To close, not to close, or to act bigger? Managing the defect of large direct inguinal hernia to reduce the risk of recurrence during laparoscopic TAPP repair: a retrospective cohort study

Hernia recurrence is a common complication after inguinal hernia repair. Recent studies suggest that laparoscopic mesh repair with closure of direct hernia defects can reduce recurrence rates. Our study examines the effectiveness of this approach. A retrospective, multi-center cohort study was conducted on cases performed from January 2013 to April 2021. Patients with direct inguinal hernias (M3 according to EHS classification) undergoing TAPP were included. Three groups were present: closed-defect group, non-closed placing a standard-sized mesh group or non-closed placing an XL-sized mesh group. A 2-year follow-up was recorded. A total of 158 direct M3 inguinal hernias in 110 patients who underwent surgery were present. After propensity score matching at a 1:1 ratio, 22 patients for each group were analyzed. The mean age of patients was 62 years (41–84); with the majority being male (84.8%). 22 patients (40 hernias) underwent closure of the defect; 22 patients (39 hernias) did not undergo closure and used a standard-sized mesh; 22 patients (27 hernias) did not undergo closure and used an XL-sized mesh. There were 5 recurrences at 1 year post-operatively: all in the non-closure group with standard-sized mesh. This difference was statistically significant (p = 0.044). There were 7 recurrences (6.6%) at 2 years post-operatively: 6 in the non-closure group with standard-sized mesh and 1 in the non-closure group with XL-sized mesh (p = 0.007). Closing large direct inguinal hernia defects has shown promise in reducing early recurrence rates. However, conducting larger RCTs in the future could provide more conclusive evidence that might impact the way we approach laparoscopic inguinal hernia repair