398 research outputs found
Understanding Tourism at Heritage Religious Sites
unDersTanDing Tourism aT heriTage religious siTe
Social preferences, accountability, and wage bargaining
We experimentally test preferences for employment in a collective wage bargaining situation with heterogeneous workers. We vary the size of the union and introduce a treatment mechanism transforming the voting game into an individual allocation task. Our results show that highly productive workers do not take employment of low productive workers into account when making wage proposals, regardless of whether only union members determine the wage or all workers. The level of pro-social preferences is small in the voting game, but it increases if the game becomes an individual allocation task. We interpret this as an accountability effect
FINEX: A Fast Index for Exact & Flexible Density-Based Clustering (Extended Version with Proofs)*
Density-based clustering aims to find groups of similar objects (i.e.,
clusters) in a given dataset. Applications include, e.g., process mining and
anomaly detection. It comes with two user parameters ({\epsilon}, MinPts) that
determine the clustering result, but are typically unknown in advance. Thus,
users need to interactively test various settings until satisfying clusterings
are found. However, existing solutions suffer from the following limitations:
(a) Ineffective pruning of expensive neighborhood computations. (b) Approximate
clustering, where objects are falsely labeled noise. (c) Restricted parameter
tuning that is limited to {\epsilon} whereas MinPts is constant, which reduces
the explorable clusterings. (d) Inflexibility in terms of applicable data types
and distance functions. We propose FINEX, a linear-space index that overcomes
these limitations. Our index provides exact clusterings and can be queried with
either of the two parameters. FINEX avoids neighborhood computations where
possible and reduces the complexities of the remaining computations by
leveraging fundamental properties of density-based clusters. Hence, our
solution is effcient and flexible regarding data types and distance functions.
Moreover, FINEX respects the original and straightforward notion of
density-based clustering. In our experiments on 12 large real-world datasets
from various domains, FINEX frequently outperforms state-of-the-art techniques
for exact clustering by orders of magnitude
Empyema after image-guided percutaneous intercostal drainage of subdiaphragmatic collection: a case series.
Background
Treatment of subdiaphragmatic collection by intercostal image-guided drain placement is associated with a risk of pleural complications including potentially life-threatening pleural empyema. Descriptions of patient characteristics and clinical course of postinterventional pleural empyema are lacking. We aim to present characteristics, clinical course and outcomes of patients with empyema after intercostal approach of drain placement.
Methods
Data was collected as a retrospective single center case series and included adult patients with decortication for treatment of pleural empyema after image-guided percutaneous intercostal drainage of a subdiaphragmatic collection between 01.01.2009 and 31.01.2021.
Results
We identified ten patients, nine male and one female, all suffering from subdiaphragmatic collection treated with intercostal drain. All patients developed pleural empyema after drain placement and received surgical decortication. Similarities between patients were drain placement under computed tomography (CT)-guidance (eight of ten patients), lateral position of the drain (seven of ten patients), drain insertion in the eighth intercostal space (ICS) (six of ten patients) and existing comorbidities as malnutrition (six of ten patients), diabetes (four of ten patients) and cancer (three of ten patients). The majority of patients had a prolonged length of hospital stay (LOS) with an average duration of 40 days. Nearly half of the patients needed intensive care unit (ICU) treatment and one patient died postoperatively from respiratory exhaustion.
Conclusions
In this series, empyema after intercostal drainage was associated with prolonged LOS and was potentially life-threatening. The most commonly shared features in our cohort were the high prevalence of comorbidities, drain insertion above ninth ICS as well as lateral position of the drain. These factors should be addressed in prospective studies to evaluate potential correlation with postinterventional empyema. For optimal management of patients with subdiaphragmatic collection treated by intercostal drainage, awareness of potential associated complications is crucial
ret2spec: Speculative Execution Using Return Stack Buffers
Speculative execution is an optimization technique that has been part of CPUs
for over a decade. It predicts the outcome and target of branch instructions to
avoid stalling the execution pipeline. However, until recently, the security
implications of speculative code execution have not been studied.
In this paper, we investigate a special type of branch predictor that is
responsible for predicting return addresses. To the best of our knowledge, we
are the first to study return address predictors and their consequences for the
security of modern software. In our work, we show how return stack buffers
(RSBs), the core unit of return address predictors, can be used to trigger
misspeculations. Based on this knowledge, we propose two new attack variants
using RSBs that give attackers similar capabilities as the documented Spectre
attacks. We show how local attackers can gain arbitrary speculative code
execution across processes, e.g., to leak passwords another user enters on a
shared system. Our evaluation showed that the recent Spectre countermeasures
deployed in operating systems can also cover such RSB-based cross-process
attacks. Yet we then demonstrate that attackers can trigger misspeculation in
JIT environments in order to leak arbitrary memory content of browser
processes. Reading outside the sandboxed memory region with JIT-compiled code
is still possible with 80\% accuracy on average.Comment: Updating to the cam-ready version and adding reference to the
original pape
Timing Aware Information Flow Security for a JavaCard-like Bytecode
AbstractCommon protection mechanisms fail to provide end-to-end security; programs with legitimate access to secret information are not prevented from leaking this to the world. Information-flow aware analyses track the flow of information through the program to prevent such leakages, but often ignore information flows through covert channels even though they pose a serious threat. A typical covert channel is to use the timing of certain events to carry information. We present a timing-aware information-flow type system for a low-level language similar to a non-trivial subset of a sequential Java bytecode. The type system is parameterized over the time model of the instructions of the language and over the algorithm enforcing low-observational equivalence, used in the prevention of implicit and timing flows
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