420 research outputs found

    Occurrence cubes : a new paradigm for aggregating species occurrence data

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    In this paper we describe a method of aggregating species occurrence data into what we coined “occurrence cubes”. The aggregated data can be perceived as a cube with three dimensions - taxonomic, temporal and geographic - and takes into account the spatial uncertainty of each occurrence. The aggregation level of each of the three dimensions can be adapted to the scope. Built on Open Science principles, the method is easily automated and reproducible, and can be used for species trend indicators, maps and distribution models. We are using the method to aggregate species occurrence data for Europe per taxon, year and 1km2 European reference grid, to feed indicators and risk mapping/modelling for the Tracking Invasive Alien Species (TrIAS) project

    Kinematic Foot Types in Youth with Equinovarus Secondary to Hemiplegia

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    Background Elevated kinematic variability of the foot and ankle segments exists during gait among individuals with equinovarus secondary to hemiplegic cerebral palsy (CP). Clinicians have previously addressed such variability by developing classification schemes to identify subgroups of individuals based on their kinematics. Objective To identify kinematic subgroups among youth with equinovarus secondary to CP using 3-dimensional multi-segment foot and ankle kinematics during locomotion as inputs for principal component analysis (PCA), and K-means cluster analysis. Methods In a single assessment session, multi-segment foot and ankle kinematics using the Milwaukee Foot Model (MFM) were collected in 24 children/adolescents with equinovarus and 20 typically developing children/adolescents. Results PCA was used as a data reduction technique on 40 variables. K-means cluster analysis was performed on the first six principal components (PCs) which accounted for 92% of the variance of the dataset. The PCs described the location and plane of involvement in the foot and ankle. Five distinct kinematic subgroups were identified using K-means clustering. Participants with equinovarus presented with variable involvement ranging from primary hindfoot or forefoot deviations to deformtiy that included both segments in multiple planes. Conclusion This study provides further evidence of the variability in foot characteristics associated with equinovarus secondary to hemiplegic CP. These findings would not have been detected using a single segment foot model. The identification of multiple kinematic subgroups with unique foot and ankle characteristics has the potential to improve treatment since similar patients within a subgroup are likely to benefit from the same intervention(s)

    Agricultural Issues

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    Low-Communication Multiparty Triple Generation for SPDZ from Ring-LPN

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    The SPDZ protocol for multi-party computation relies on a correlated randomness setup consisting of authenticated, multiplication triples. A recent line of work by Boyle et al. (Crypto 2019, Crypto 2020) has investigated the possibility of producing this correlated randomness in a silent preprocessing phase, which involves a “small” setup protocol with less communication than the total size of the triples being produced. These works do this using a tool called a pseudorandom correlation generator (PCG), which allows a large batch of correlated randomness to be compressed into a set of smaller, correlated seeds. However, existing methods for compressing SPDZ triples only apply to the 2-party setting. In this work, we construct a PCG for producing SPDZ triples over large prime fields in the multi-party setting. The security of our PCG is based on the ring-LPN assumption over fields, similar to the work of Boyle et al. (Crypto 2020) in the 2-party setting. We also present a corresponding, actively secure setup protocol, which can be used to generate the PCG seeds and instantiate SPDZ with a silent preprocessing phase. As a building block, which may be of independent interest, we construct a new type of 3-party distributed point function supporting outputs over arbitrary groups (including large prime order), as well as an efficient protocol for setting up our DPF keys with active security

    Atraumatic Restorative Treatment (ART) in Pediatric Dentistry Residency Programs: A Survey of Program Directors

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    Purpose: The purpose of this study was to investigate the extent of clinical training on atraumatic restorative treatment (ART) among pediatric dentistry residency programs and assess program directors’ attitudes toward ART. Methods: All U.S. Pediatric Dentistry residency programs’ directors were asked to complete a web-based survey. Sixty-one of the 76 directors (80 percent) completed the survey, with no significant response bias. Results: Eighty-nine percent of the responding programs provided clinical instruction on ART. Of these, 30 percent provided ART training often/very often. ART was used mostly in single-surface cavities (43 percent) and as an interim treatment in primary teeth (57 percent). Factors associated with ART clinical training included not placing amalgams in primary teeth (P<.03) and having directors with positive attitudes toward ART (P<.001). Factors associated with directors’ positive attitudes included believing that child’s caries risk (P<.006), professional guidelines (P<.003), and patient insurance status (P<.04) were all important in selecting restorative treatment. Conclusions: Atraumatic restorative therapy appears to be underused in pediatric dentistry residency programs in the United States. Residency directors’ attitudes were highly predictive of the amount of clinical training provided, suggesting that directors need to be better informed about the use of ART

    Synthesizing Field and Experimental Observations to Investigate the Behavior of Pyroclastic Density Currents

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    One of the major hazards associated with volcanic eruptions are pyroclastic density currents (PDCs), which are fast-moving volcanic avalanches consisting of ash, boulders, and gas. Because of their unpredictability, studying PDCs in real time is dangerous and difficult. Therefore, we investigate the deposits produced by PDCs and use granular flow experiments to simulate PDCs in the laboratory. The experimental results allow us to understand sediment transport and erosional processes at small scales, and then we can extrapolate those results to natural PDCs. By better understanding what controls PDC behavior, we hope to ultimately improve risk assessment for these dangerous flows

    Distributed (Correlation) Samplers: How to Remove a Trusted Dealer in One Round

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    Structured random strings (SRSs) and correlated randomness are important for many cryptographic protocols. In settings where interaction is expensive, it is desirable to obtain such randomness in as few rounds of communication as possible; ideally, simply by exchanging one reusable round of messages which can be considered public keys. In this paper, we describe how to generate any SRS or correlated randomness in such a single round of communication, using, among other things, indistinguishability obfuscation. We introduce what we call a distributed sampler, which enables nn parties to sample a single public value (SRS) from any distribution. We construct a semi-malicious distributed sampler in the plain model, and use it to build a semi-malicious public-key PCF (Boyle et al, FOCS 2020) in the plain model. A public-key PCF can be thought of as a distributed correlation sampler; instead of producing a public SRS, it gives each party a private random value (where the values satisfy some correlation). We introduce a general technique called an anti-rusher which compiles any one-round protocol with semi-malicious security without inputs to a similar one-round protocol with active security by making use of a programmable random oracle. This gets us actively secure distributed samplers and public-key PCFs in the random oracle model. Finally, we explore some tradeoffs. Our first PCF construction is limited to reverse-sampleable correlations (where the random outputs of honest parties must be simulatable given the random outputs of corrupt parties); we additionally show a different construction without this limitation, but which does not allow parties to hold secret parameters of the correlation. We also describe how to avoid the use of a random oracle at the cost of relying on sub-exponentially secure indistinguishability obfuscation

    On the (Im)possibility of Distributed Samplers: Lower Bounds and Party-Dynamic Constructions

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    Distributed samplers, introduced by Abram, Scholl and Yakoubov (Eurocrypt ’22), are a one-round, multi-party protocol for securely sampling from any distribution. We give new lower and upper bounds for constructing distributed samplers in challenging scenarios. First, we consider the feasibility of distributed samplers with a malicious adversary in the standard model; the only previous construction in this setting relies on a random oracle. We show that for any UC-secure construction in the standard model, even with a CRS, the output of the sampling protocol must have low entropy. This essentially implies that this type of construction is useless in applications. Secondly, we study the question of building distributed samplers in the party-dynamic setting, where parties can join in an ad-hoc manner, and the total number of parties is unbounded. Here, we obtain positive results. First, we build a special type of unbounded universal sampler, which after a trusted setup, allows sampling from any distributed with unbounded size. Our construction is in the shared randomness model, where the parties have access to a shared random string, and uses indistinguishability obfuscation and somewhere statistically binding hashing. Next, using our unbounded universal sampler, we construct distributed universal samplers in the party-dynamic setting. Our first construction satisfies one-time selective security in the shared randomness model. Our second construction is reusable and secure against a malicious adversary in the random oracle model. Finally, we show how to use party-dynamic, distributed universal samplers to produce ideal, correlated randomness in the party-dynamic setting, in a single round of interaction

    Consumers’ Choice of Dentists: How and Why People Choose Dental School Faculty Members as Their Oral Health Care Providers

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    This study aimed to better understand how and why people choose dental school faculty members as their oral health care providers. Increasing financial constraints in U.S. dental schools have led their administrators to seek alternative funding sources, one of which can be revenues from dental school faculty practice. To effectively promote faculty practice, it is necessary to understand how and why one chooses a dental school faculty member as his or her oral health care provider. A survey of 1,150 dental school faculty practice patients who recently chose their dentist was conducted, and 221 responded. The information sources these respondents said they used and rated highly were other dentists, friends, family members, clinic website, the Internet, and the insurance directory. Dentist-related attributes that were perceived to be important were quality of care, professional competence of dentist, and explanation of treatment/patient participation in the treatment decision. Dental practice-related attributes perceived to be important were the ability to get appointments at convenient times, reasonable waiting time to get appointments, and attitude/helpfulness of staff. This study found that traditionally popular (family, friends) and newly emerging information sources (the Internet, clinic website, and insurance directory) were both used and perceived to be important by patients of the dental school faculty practice. Dental schools and dentists can use this study’s findings to select appropriate communication channels to promote their practices and to focus on attributes that dental consumers value the most
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