Reguladores vegetais no enraizamento e desenvolvimento de gemas de cana-de-açúcar tratadas termicamente

Este trabalho teve por finalidade estudar o efeito de reguladores vegetais sobre a emergência e desenvolvimento inicial de gemas de cana-de-açúcar 'IAC 52-150', submetidas ao tratamento térmico por via úmida. Para tanto, as gemas foram tratadas durante uma hora em soluções de ácido indolilacético (IAA) e ácido naftalenacêtico (NAA), nas concentrações de 10, 25, 50 e 100 ppm, em ácido indolbutírico (IBA) nas concentrações de 10 e 25 ppm e em água pura (testemunha). Imediatamente após o tratamento, as gemas foram plantadas em germinadores de areia. IBA 10 ppm tendeu a favorecer a emergência e o enraizamento das gemas. IAA não afetou a emergência, enraizamento e peso da parte aérea da cana-de-açúcar. Aplicação de NAA 100 ppm reduziu a porcentagem de emergência e o peso da parte aérea do cultivar IAC 52-150.The effect of growth regulators on the germination and initial development of sugar cane shoots submitted to high temperature treatment by the moist method was studied. The shoots were treated during 1 hour with indoleacetic´acid (IAA) and naphthaleneacetic acid (NAA) at the concentrations of 10, 25, 50 and 100 ppm, with indolebutyric acid (IBA) at the concentrations of 10 and 25 ppm and with pure water (control). Immediately after the treatment, the shoots were planted in sand germinators. The results showed that treatment with IBA 10 ppm promote a tendency to induce germination and roots development. The root system development was not affected by other treatments, but the development of the aerial portion was adversely affected by NAA 100 ppm. The results showed that, after 60 days, the number of emerged shoots was significantly lower than that of the control in the plots treated with 100 ppm of NAA

Increased Resilience in Threshold Cryptography: Sharing a Secret with Devices That Cannot Store Shares

Threshold cryptography has been used to secure data and control access by sharing a private cryptographic key over different devices. This means that a minimum number of these devices, the threshold $t+1$, need to be present to use the key. The benefits are increased security, because an adversary can compromise up to $t$ devices, and resilience, since any subset of $t+1$ devices is sufficient. Many personal devices are not suitable for threshold schemes, because they do not offer secure storage, which is needed to store shares of the private key. This article presents several protocols in which shares are stored in protected form (possibly externally). This makes them suitable for low-cost devices with a factory-embedded key, e.g., car keys and access cards. All protocols are verifiable through public broadcast, thus without private channels. In addition, distributed key generation does not require all devices to be present

A rooted map invariant, non-orientability and Jack symmetric functions

AbstractThe existence of a non-negative integer-valued invariant, called the Map–Jack invariant, for rooted maps has been conjectured by Goulden and Jackson [I.P. Goulden, D.M. Jackson, Connection coefficients, matchings, maps and combinatorial conjectures for Jack symmetric functions, Trans. Amer. Math. Soc. 348 (1996) 873–892]. It has the defining property that, if it is marked by an indeterminate b, then the generating series for rooted maps in locally orientable surfaces is a particular series, involving the Jack symmetric function Jλ(b+1), that specialises to the generating series for rooted maps in orientable surfaces for b=0 (and clearly to all surfaces for b=1). We propose a candidate Map–Jack invariant η that is determined by depth first search and by the local topological effect of deleting edges from maps, and give results that support its candidacy. In particular, we prove its correctness up to face partition. We also show how the algorithm for determining η may be associated with the Jack symmetric functions. This is achieved by means of the Laplace–Beltrami operator

On the Soundness of Restricted Universal Designated Verifier Signatures and Dedicated Signatures

International audienceIn 2006, Huang, Susilo, Mu and Zhang proposed the concept of \emph{restricted universal designated verifier signatures} while Klonowski, Kubiak, Kutylowski and Lauks proposed independently the \emph{dual} primitive of \emph{dedicated signatures}. In both notions, a signature holder can convince one or more verifiers of his knowledge of a digital signature, but cannot exploit this knowledge without being \emph{punished} for that. In this paper, we state that a signature holder may generically provide a proof that it has a certain signature without being punished and that consequently both primitives cannot fulfill their alleged security goals. To demonstrate the feasibility of this claim, we propose the first non-interactive universal designated verifier proof of the possession of an Elgamal or a DSA signature in the random oracle model. This construction may be of independent interest

Securing identity assignment using implicit certificates in P2P overlays

The security of the Peer-to-Peer (P2P) overlays networks has been questioned for years. Many works have been proposed to provide secure routing, anonymity, reputation systems, confidentiality, etc. However, the identity assignment has been less considered. These networks are designed so that each user has a unique identifier (nodeID), but the most of identity assignment systems allow malicious users to obtain a set of nodeIDs or even select certain identifiers. Thus, these users can disrupt the proper operation of a P2P overlay. In this paper, we propose a nodeID assignment protocol based on the issue of implicit certificates. Our purpose is to provide security services to struggle against the most of security threats in these networks with special attention to the identity assignment. This approach is based on the use of certificates and the joint generation of nodeIDs between a Certification Authority (CA) and the user. In addition, the use of implicit certificates presents certain advantages over the use of traditional certificates (explicit certificates).Peer ReviewedPostprint (published version

Global spatial risk assessment of sharks under the footprint of fisheries

Effective ocean management and conservation of highly migratory species depends on resolving overlap between animal movements and distributions and fishing effort. Yet, this information is lacking at a global scale. Here we show, using a big-data approach combining satellite-tracked movements of pelagic sharks and global fishing fleets, that 24% of the mean monthly space used by sharks falls under the footprint of pelagic longline fisheries. Space use hotspots of commercially valuable sharks and of internationally protected species had the highest overlap with longlines (up to 76% and 64%, respectively) and were also associated with significant increases in fishing effort. We conclude that pelagic sharks have limited spatial refuge from current levels of high-seas fishing effort. Results demonstrate an urgent need for conservation and management measures at high-seas shark hotspots and highlight the potential of simultaneous satellite surveillance of megafauna and fishers as a tool for near-real time, dynamic management

Global variation in anastomosis and end colostomy formation following left-sided colorectal resection

Background: End colostomy rates following colorectal resection vary across institutions in high-income settings, being influenced by patient, disease, surgeon and system factors. This study aimed to assess global variation in end colostomy rates after left-sided colorectal resection. Methods: This study comprised an analysis of GlobalSurg-1 and-2 international, prospective, observational cohort studies (2014, 2016), including consecutive adult patients undergoing elective or emergency left-sided colorectal resection within discrete 2-week windows. Countries were grouped into high-, middle-and low-income tertiles according to the United Nations Human Development Index (HDI). Factors associated with colostomy formation versus primary anastomosis were explored using a multilevel, multivariable logistic regression model. Results: In total, 1635 patients from 242 hospitals in 57 countries undergoing left-sided colorectal resection were included: 113 (6·9 per cent) from low-HDI, 254 (15·5 per cent) from middle-HDI and 1268 (77·6 percent) from high-HDI countries. There was a higher proportion of patients with perforated disease (57·5, 40·9 and 35·4 per cent; P < 0·001) and subsequent use of end colostomy (52·2, 24·8 and 18·9 per cent; P < 0·001) in low-compared with middle-and high-HDI settings. The association with colostomy use in low-HDI settings persisted (odds ratio (OR) 3·20, 95 per cent c.i. 1·35 to 7·57; P = 0·008) after risk adjustment for malignant disease (OR 2·34, 1·65 to 3·32; P < 0·001), emergency surgery (OR 4·08, 2·73 to 6·10; P < 0·001), time to operation at least 48 h (OR 1·99, 1·28 to 3·09; P = 0·002) and disease perforation (OR 4·00, 2·81 to 5·69; P < 0·001). Conclusion: Global differences existed in the proportion of patients receiving end stomas after left-sided colorectal resection based on income, which went beyond case mix alone

Global variation in anastomosis and end colostomy formation following left-sided colorectal resection

Background: End colostomy rates following colorectal resection vary across institutions in high-income settings, being influenced by patient, disease, surgeon and system factors. This study aimed to assess global variation in end colostomy rates after left-sided colorectal resection. Methods: This study comprised an analysis of GlobalSurg-1 and -2 international, prospective, observational cohort studies (2014, 2016), including consecutive adult patients undergoing elective or emergency left-sided colorectal resection within discrete 2-week windows. Countries were grouped into high-, middle- and low-income tertiles according to the United Nations Human Development Index (HDI). Factors associated with colostomy formation versus primary anastomosis were explored using a multilevel, multivariable logistic regression model. Results: In total, 1635 patients from 242 hospitals in 57 countries undergoing left-sided colorectal resection were included: 113 (6·9 per cent) from low-HDI, 254 (15·5 per cent) from middle-HDI and 1268 (77·6 per cent) from high-HDI countries. There was a higher proportion of patients with perforated disease (57·5, 40·9 and 35·4 per cent; P < 0·001) and subsequent use of end colostomy (52·2, 24·8 and 18·9 per cent; P < 0·001) in low- compared with middle- and high-HDI settings. The association with colostomy use in low-HDI settings persisted (odds ratio (OR) 3·20, 95 per cent c.i. 1·35 to 7·57; P = 0·008) after risk adjustment for malignant disease (OR 2·34, 1·65 to 3·32; P < 0·001), emergency surgery (OR 4·08, 2·73 to 6·10; P < 0·001), time to operation at least 48 h (OR 1·99, 1·28 to 3·09; P = 0·002) and disease perforation (OR 4·00, 2·81 to 5·69; P < 0·001). Conclusion: Global differences existed in the proportion of patients receiving end stomas after left-sided colorectal resection based on income, which went beyond case mix alone