On the matrix code of quadratic relationships for a Goppa code

In this article, we continue the analysis started in \cite{CMT23} for the matrix code of quadratic relationships associated with a Goppa code. We provide new sparse and low-rank elements in the matrix code and categorize them according to their shape. Thanks to this description, we prove that the set of rank 2 matrices in the matrix codes associated with square-free binary Goppa codes, i.e. those used in Classic McEiece, is much larger than what is expected, at least in the case where the Goppa polynomial degree is 2. We build upon the algebraic determinantal modeling introduced in \cite{CMT23} to derive a structural attack on these instances. Our method can break in just a few seconds some recent challenges about key-recovery attacks on the McEliece cryptosystem, consistently reducing their estimated security level. We also provide a general method, valid for any Goppa polynomial degree, to transform a generic pair of support and multiplier into a pair of support and Goppa polynomial

Polynomial time attack on high rate random alternant codes

A long standing open question is whether the distinguisher of high rate alternant codes or Goppa codes \cite{FGOPT11} can be turned into an algorithm recovering the algebraic structure of such codes from the mere knowledge of an arbitrary generator matrix of it. This would allow to break the McEliece scheme as soon as the code rate is large enough and would break all instances of the CFS signature scheme. We give for the first time a positive answer for this problem when the code is {\em a generic alternant code} and when the code field size $q$ is small : $q \in \{2,3\}$ and for {\em all} regime of other parameters for which the aforementioned distinguisher works. This breakthrough has been obtained by two different ingredients : (i) a way of using code shortening and the component-wise product of codes to derive from the original alternant code a sequence of alternant codes of decreasing degree up to getting an alternant code of degree $3$ (with a multiplier and support related to those of the original alternant code); (ii) an original Gr\"obner basis approach which takes into account the non standard constraints on the multiplier and support of an alternant code which recovers in polynomial time the relevant algebraic structure of an alternant code of degree $3$ from the mere knowledge of a basis for it

A new approach based on quadratic forms to attack the McEliece cryptosystem

We bring in here a novel algebraic approach for attacking the McEliece cryptosystem. It consists in introducing a subspace of matrices representing quadratic forms. Those are associated with quadratic relationships for the component-wise product in the dual of the code used in the cryptosystem. Depending on the characteristic of the code field, this space of matrices consists only of symmetric matrices or skew-symmetric matrices. This matrix space is shown to contain unusually low-rank matrices (rank $2$ or $3$ depending on the characteristic) which reveal the secret polynomial structure of the code. Finding such matrices can then be used to recover the secret key of the scheme. We devise a dedicated approach in characteristic $2$ consisting in using a Gr\"obner basis modeling that a skew-symmetric matrix is of rank $2$. This allows to analyze the complexity of solving the corresponding algebraic system with Gr\"obner bases techniques. This computation behaves differently when applied to the skew-symmetric matrix space associated with a random code rather than with a Goppa or an alternant code. This gives a distinguisher of the latter code family. We give a bound on its complexity which turns out to interpolate nicely between polynomial and exponential depending on the code parameters. A distinguisher for alternant/Goppa codes was already known [FGO+11]. It is of polynomial complexity but works only in a narrow parameter regime. This new distinguisher is also polynomial for the parameter regime necessary for [FGO+11] but contrarily to the previous one is able to operate for virtually all code parameters relevant to cryptography. Moreover, we use this matrix space to find a polynomial time attack of the McEliece cryptosystem provided that the Goppa code is distinguishable by the method of [FGO+11] and its degree is less than $q-1$, where $q$ is the alphabet size of the code.Comment: 61 page

On the dimension and structure of the square of the dual of a Goppa code

International audienceThe Goppa Code Distinguishing (GD) problem asks to distinguish efficiently a generator matrix of a Goppa code from a randomly drawn one. We revisit a distinguisher for alternant and Goppa codes through a new approach, namely by studying the dimension of square codes. We provide here a rigorous upper bound for the dimension of the square of the dual of an alternant or Goppa code, while the previous approach only provided algebraic explanations based on heuristics. Moreover, for Goppa codes, our proof extends to the non-binary case as well, thus providing an algebraic explanation for the distinguisher which was missing up to now. All the upper bounds are tight and match experimental evidence. Our work also introduces new algebraic results about products of trace codes in general and of dual of alternant and Goppa codes in particular, clarifying their square code structure. This might be of interest for cryptanalysis purposes

Efectos urbanos de la construcción del parque lineal y ciclovía Pocuro, en Santiago / Urban effects of the construction of the Pocuro linear park and cycle path, in Santiago

The effects of property development on urban vitality and on the land prices from the transformation of the profile of Pocuro Ave. (eastern Santiago), where a linear park of almost 1.5 kilometers was built in 1997, with a cycle path and promenade, are evaluated. A list of the constructions built on the street from 1960 to the present date was made, along with a count of the people who used the street and interviews with the store keepers there. The results show a 223% increase in the m2 built in the last 20 years compared to the previous period, as well as an intensive and diverse use of the street. Both the real-estate activity and the intensive use of the street were positively valued by the store keepers. Finally, it is detected that the payment of building permits has managed to cover 98.5% of what was originally invested by the council, revealing that this type of investment can be highly profitable for councils.Se presenta una evaluación de los efectos en la actividad inmobiliaria en la vitalidad urbana y en los precios del suelo de la transformación del perfil de la calle Pocuro (oriente de Santiago), donde se construyó, en 1997, un parque lineal de casi 1.5 kilómetros, con una ciclovía y un área de caminata. Para ello se expone un catastro de las construcciones levantadas sobre la calle desde 1960 a la fecha, un conteo de personas que han ocupado la calle y entrevistas a locatarios de la misma. Los resultados muestran un alza de 223% en los metros cuadrados construidos en últimos veinte años respecto del período anterior, además de un uso intenso y diverso de la calle. Tanto la actividad inmobiliaria como el intenso uso de la calle resulta valorado positivamente por los locatarios. Finalmente, se detecta que el pago de permisos de edificación ha logrado cubrir el 98.5% de lo invertido originalmente por el municipio, lo que revela que este tipo de inversiones puede ser altamente rentable para las municipalidades

Il biofeedback preoperatorio migliora il recupero della continenza a seguito di prostatectomia radicale: una revisione sistematica con meta-analisi

BACKGROUND:  Postoperative urinary incontinence is the overall result of urethral sphincter incompetence and modifications in urethral length after radical prostatectomy. Findings for preoperative interventions targeted at preventing post-prostatectomy incontinence include preoperative pelvic floor muscle training (PFMT) and biodfeedback (BFB), which can be managed by nurses in many countries and have been used for decades to speed up continence recovery after surgery. AIM: to determine the effectiveness of preoperative biofeedback (BFB) for post-prostatectomy urinary incontinence compared to pelvic training without BFB, considering the variability between the results of the available studies.  METHODS: A systematic review and meta-analysis was conducted, analyzing the indications provided by the literature regarding preoperative biofeedback for preventing urinary incontinence after open radical prostatectomy, in terms of treatment regimens, timing for beginning the sessions, number of contraction and relaxation exercises, and scheduled work at home. Literature search on Pubmed, CINAHL, Cochrane Library, Web of Science, Scopus, EMBASE, and PEdro. RESULTS: Despite only three papers being suitable for metanalysis, our results support BFB over written instructions for continence recovery after both 3 and 6 moths from surgery. Implementing progressive programs with many different muscular exercises and including relaxation are the main recommendations. CONCLUSIONS: Preoperative biofeedback leads to improved urinary continence after 3 and 6 months from radical prostatectomy. Future studies should focus on the characteristics and number of pelvic muscle contractions required during biofeedback in order to maximize effectiveness.BACKGROUND: L'incontinenza urinaria postoperatoria è il risultato complessivo dell'incompetenza dello sfintere uretrale e delle modifiche della lunghezza dell'uretra dopo la prostatectomia radicale. I risultati degli interventi preoperatori mirati a prevenire l'incontinenza post-prostatectomia includono l'allenamento preoperatorio dei muscoli del pavimento pelvico (PFMT) e il biodfeedback (BFB), che possono essere gestiti dal personale infermieristico in molti Paesi. OBIETTIVO: determinare l'efficacia del biofeedback preoperatorio (BFB) per l'incontinenza urinaria post-prostatectomia rispetto al training pelvico senza BFB, considerando la variabilità dei risultati degli studi disponibili.  METODI: è stata condotta una revisione sistematica con meta-analisi, analizzando le indicazioni fornite dalla letteratura sul biofeedback preoperatorio per la prevenzione dell'incontinenza urinaria in termini di regimi di trattamento, tempi di inizio delle sessioni, numero di esercizi di contrazione e rilassamento e lavoro programmato a casa. La ricerca della letteratura è stata effettuata su Pubmed, CINAHL, Cochrane Library, Web of Science, Scopus, EMBASE e PEdro. RISULTATI: nonostante solo tre articoli siano stati adatti alla metanalisi, i nostri risultati supportano il BFB rispetto alle istruzioni scritte per il recupero della continenza dopo 3 e 6 mesi dall'intervento. L'implementazione di programmi progressivi con molti esercizi muscolari diversi e l'inclusione del rilassamento sono le principali raccomandazioni. CONCLUSIONI: Il biofeedback preoperatorio porta a un miglioramento della continenza urinaria dopo 3 e 6 mesi dalla prostatectomia radicale. Gli studi futuri dovrebbero concentrarsi sulle caratteristiche e sul numero di contrazioni muscolari pelviche richieste durante il biofeedback per massimizzare l'efficacia.Il biofeedback preoperatorio migliora il recupero della continenza dopo la prostatectomia aperta: una revisione sistematica e una meta-analis

The role of the meridional sea surface temperature gradient in controlling the Caribbean low-level jet

The Caribbean low‐level jet (CLLJ) is an important modulator of regional climate, especially precipitation, in the Caribbean and Central America. Previous work has inferred, due to their semiannual cycle, an association between CLLJ strength and meridional sea surface temperature (SST) gradients in the Caribbean Sea, suggesting that the SST gradients may control the intensity and vertical shear of the CLLJ. In addition, both the horizontal and vertical structure of the jet have been related to topographic effects via interaction with the mountains in Northern South America (NSA), including funneling effects and changes in the meridional geopotential gradient. Here we test these hypotheses, using an atmospheric general circulation model to perform a set of sensitivity experiments to examine the impact of both SST gradients and topography on the CLLJ. In one sensitivity experiment, we remove the meridional SST gradient over the Caribbean Sea and in the other, we flatten the mountains over NSA. Our results show that the SST gradient and topography have little or no impact on the jet intensity, vertical, and horizontal wind shears, contrary to previous works. However, our findings do not discount a possible one‐way coupling between the SST and the wind over the Caribbean Sea through friction force. We also examined an alternative approach based on barotropic instability to understand the CLLJ intensity, vertical, and horizontal wind shears. Our results show that the current hypothesis about the CLLJ must be reviewed in order to fully understand the atmospheric dynamics governing the Caribbean region.Consejo Superior Universitario Centroamericano/[805-A9-532]/CSUCA/GuatemalaAgencia Sueca de Desarrollo Internacional/[805-A9-532]/ASDI/SueciaUniversidad de Costa Rica/[805-B6-143]/UCR/Costa RicaConsejo Nacional para Investigaciones Científicas y Tecnológicas/[805-B6-143]/CONICIT/Costa RicaMinisterio de Ciencia, Tecnología y Telecomunicaciones/[805-B6-143]/MICITT/Costa RicaUCR::Vicerrectoría de Investigación::Unidades de Investigación::Ciencias Básicas::Centro de Investigaciones Geofísicas (CIGEFI)UCR::Vicerrectoría de Investigación::Unidades de Investigación::Ciencias Básicas::Centro de Investigación en Ciencias del Mar y Limnología (CIMAR)UCR::Vicerrectoría de Docencia::Ciencias Básicas::Facultad de Ciencias::Escuela de Físic

Less invasive methods of advanced hemodynamic monitoring: principles, devices, and their role in the perioperative hemodynamic optimization.

The monitoring of the cardiac output (CO) and other hemodynamic parameters, traditionally performed with the thermodilution method via a pulmonary artery catheter (PAC), is now increasingly done with the aid of less invasive and much easier to use devices. When used within the context of a hemodynamic optimization protocol, they can positively influence the outcome in both surgical and non-surgical patient populations. While these monitoring tools have simplified the hemodynamic calculations, they are subject to limitations and can lead to erroneous results if not used properly. In this article we will review the commercially available minimally invasive CO monitoring devices, explore their technical characteristics and describe the limitations that should be taken into consideration when clinical decisions are made

Association of Variants in the SPTLC1 Gene With Juvenile Amyotrophic Lateral Sclerosis

Importance: Juvenile amyotrophic lateral sclerosis (ALS) is a rare form of ALS characterized by age of symptom onset less than 25 years and a variable presentation.Objective: To identify the genetic variants associated with juvenile ALS.Design, Setting, and Participants: In this multicenter family-based genetic study, trio whole-exome sequencing was performed to identify the disease-associated gene in a case series of unrelated patients diagnosed with juvenile ALS and severe growth retardation. The patients and their family members were enrolled at academic hospitals and a government research facility between March 1, 2016, and March 13, 2020, and were observed until October 1, 2020. Whole-exome sequencing was also performed in a series of patients with juvenile ALS. A total of 66 patients with juvenile ALS and 6258 adult patients with ALS participated in the study. Patients were selected for the study based on their diagnosis, and all eligible participants were enrolled in the study. None of the participants had a family history of neurological disorders, suggesting de novo variants as the underlying genetic mechanism.Main Outcomes and Measures: De novo variants present only in the index case and not in unaffected family members.Results: Trio whole-exome sequencing was performed in 3 patients diagnosed with juvenile ALS and their parents. An additional 63 patients with juvenile ALS and 6258 adult patients with ALS were subsequently screened for variants in the SPTLC1 gene. De novo variants in SPTLC1 (p.Ala20Ser in 2 patients and p.Ser331Tyr in 1 patient) were identified in 3 unrelated patients diagnosed with juvenile ALS and failure to thrive. A fourth variant (p.Leu39del) was identified in a patient with juvenile ALS where parental DNA was unavailable. Variants in this gene have been previously shown to be associated with autosomal-dominant hereditary sensory autonomic neuropathy, type 1A, by disrupting an essential enzyme complex in the sphingolipid synthesis pathway.Conclusions and Relevance: These data broaden the phenotype associated with SPTLC1 and suggest that patients presenting with juvenile ALS should be screened for variants in this gene.</p