This book takes an extensive look at the many different types of users and cultures that comprise the popular social media platform Tumblr. Though it does not receive nearly as much attention as ...other social media such as Twitter or Facebook, Tumblr and its users have been hugely influential in creating and shifting popular culture, especially progressive youth culture, with the New York Times referring to 2014 as the dawning of the “age of Tumblr activism.” Perfect for those unfamiliar with the platform as well as those who grew up on it, this volume contains essays and artwork that span many different topics: fandom; platform structure and design; race, gender and sexuality, including queer and trans identities; aesthetics; disability and mental health; and social media privacy and ethics. An entire generation of young people that is now beginning to influence mass culture and politics came of age on Tumblr, and this volume is an indispensable guide to the many ways this platform works.
Diphenyl diselenide (DPDS) is an organoselenium compound with interesting pharmacological activities and various toxic effects. In previous reports, we demonstrated the pro-oxidant action and the ...mutagenic properties of this molecule in bacteria, yeast and cultured mammalian cells. This study investigated the genotoxic effects of DPDS in multiple organs (brain, kidney, liver, spleen, testes and urinary bladder) and tissues (bone marrow, lymphocytes) of mice using in vivo comet assay, in order to determine the threshold of dose at which it has beneficial or toxic effects. We assessed the mechanism underlying the genotoxicity through the measurement of GSH content and thiobarbituric acid reactive species, two oxidative stress biomarkers. Male CF-1 mice were given 0.2–200
μmol/kg BW DPDS intraperitonially. DPDS induced DNA damage in brain, liver, kidney and testes in a dose response manner, in a broad dose range at 75–200
μmol/kg with the brain showing the highest level of damage. Overall, our analysis demonstrated a high correlation among decreased levels of GSH content and an increase in lipid peroxidation and DNA damage. This finding establishes an interrelationship between pro-oxidant and genotoxic effects. In addition, DPDS was not genotoxic and did not increase lipid peroxidation levels in any organs at doses <50
μmol/kg. Finally, pre-treatment with
N-acetyl-cysteine completely prevented DPDS-induced oxidative damage by the maintenance of cellular GSH levels, reinforcing the positive relationship of DPDS-induced GSH depletion and DNA damage. In summary, DPDS induces systemic genotoxicity in mammals as it causes DNA damage in vital organs like brain, liver, kidney and testes.
We present a scheme that achieves self-stabilizing Byzantine digital clock synchronization assuming a “synchronous” system. This synchronicity is established by the assumption of a common “beat” ...delivered with a regularity in the order of the network message delay, thus enabling the nodes to execute in lock-step. The system can be subjected to severe transient failures with a permanent presence of Byzantine nodes. Our algorithm guarantees eventually synchronized digital clock counters, i.e. common increasing integer counters associated with each beat. We then show how to achieve regular clock synchronization, progressing at real-time rate and with high granularity, from the synchronized digital clock counters.
There is one previous self-stabilizing Byzantine clock synchronization algorithm, which also converges in linear time (relying on an underlying pulse mechanism), but it requires to execute and terminate Byzantine agreement in between consecutive pulses. Such a scheme, although it does not assume a synchronous system, cannot be easily transformed to a synchronous system in which the pulses (beats) are in the order of the message delay time apart. The only other digital clock synchronization algorithm operating in a similar synchronous model converges in expected exponential time. Our algorithm converges (deterministically) in linear time.
The ProSeal laryngeal mask airway (PLMA) is increasingly used for surgical procedures that might require the intraoperative use of neuromuscular blocking agents. The airway seal of the PLMA depends ...on the interplay of the surrounding soft tissue of the neck and the cuff of the mask. An intraoperative neuromuscular blockade could lead to a decrease of the airway leak pressure (P (leak)) secondary to the relaxation of the muscles of the neck. With this study we tested the hypothesis that a neuromuscular blockade can result in a decreased P (leak) of the PLMA.
The P (leak) of the PLMA was studied in 73 female patients under total intravenous anaesthesia with propofol (0.1 - 0.15 mg kg (-1) min (-1)) and remifentanil (0.1 - 0.3 microg kg (-1) min (-1)) before and after a complete neuromuscular blockade produced by intravenous injection of 0.6 mg kg (-1) Rocuronium.
The P (leak) decreased by more than 10 % of the baseline P (leak) in 8 out of 73 patients (11 %); however, in the entire study population there was no significant difference between the mean baseline P (leak) (28.5 +/- 7.3 cm H(2)O) and the mean P (leak) after complete neuromuscular blockade (29.1 +/- 7.0 cm H(2)O); (p = 0.128).
No general correlation between application of a neuromuscular blocking agent and a decrease of the mean P (leak) was found. However, the decrease of the P (leak) by more than 10 % in 11 % of the patients shows that in certain patients the application of neuromuscular blocking agents can result in a decreased P (leak) of the PLMA and indicates the necessity to control the P (leak) of the PLMA under complete muscle paralysis preoperatively when neuromuscular blocking agents are used.
Asymmetric synthesis of umuravumbolide Reddy, M V; Rearick, J P; Hoch, N ...
Organic letters,
2001-Jan-11, 20010111, Letnik:
3, Številka:
1
Journal Article
Recenzirano
figure: see text This first asymmetric synthesis of enantiopure desacetylumuravumbolide and umuravumbolide via asymmetric reduction, allylboration, and ring-closing metathesis confirms their revised ...structures and configurations. A convenient procedure to upgrade the enantiopurity of alpha,beta-acetylenic alcohols is also described.
Consider a distributed network in which up to a third of the nodes may be Byzantine, and in which the non-faulty nodes may be subject to transient faults that alter their memory in an arbitrary ...fashion. Within the context of this model, we are interested in the digital clock synchronization problem; which consists of agreeing on bounded integer counters, and increasing these counters regularly. It has been postulated in the past that synchronization cannot be solved in a Byzantine tolerant and self-stabilizing manner. The first solution to this problem had an expected exponential convergence time. Later, a deterministic solution was published with linear convergence time, which is optimal for deterministic solutions. In the current paper we achieve an expected constant convergence time. We thus obtain the optimal probabilistic solution, both in terms of convergence time and in terms of resilience to Byzantine adversaries.
Gradecast is a simple three-round algorithm presented by Feldman and Micali 4. The current work presents two very simple algorithms that utilize Gradecast to achieve Byzantine agreement and to solve ...the Approximate agreement problem 2.
Consider a fully connected network where up to t processes may crash, and all processes start in an arbitrary memory state. The self-stabilizing firing squad problem consists of eventually ...guaranteeing simultaneous response to an external input. This is modeled by requiring that the non-crashed processes “fire” simultaneously if some correct process received an external “go” input, and that they only fire as a response to some process receiving such an input. This paper presents Fire-Squad, the first self-stabilizing firing squad algorithm.
The Fire-Squad algorithm is optimal in two respects: (a) Once the algorithm is in a safe state, it fires in response to a go input as fast as any other algorithm does, and (b) Starting from an arbitrary state, it converges to a safe state as fast as any other algorithm does.
“Pulse Synchronization” intends to invoke a recurring distributed event at the different nodes, of a distributed system as simultaneously as possible and with a frequency that matches a predetermined ...regularity. This paper shows how to achieve that goal when the system is facing both transient and permanent (Byzantine) failures.
Byzantine nodes might incessantly try to de-synchronize the correct nodes. Transient failures might throw the system into an arbitrary state in which correct nodes have no common notion what-so-ever, such as time or round numbers, and thus cannot use any aspect of their own local states to infer anything about the states of other correct nodes. The algorithm we present here guarantees that eventually all correct nodes will invoke their pulses within a very short time interval of each other and will do so regularly.
The problem of pulse synchronization was recently solved in a system in which there exists an outside beat system that synchronously signals all nodes at once. In this paper we present a solution for a bounded-delay system. When the system in a steady state, a message sent by a correct node arrives and is processed by all correct nodes within a bounded time, say d time units, where at steady state the number of Byzantine nodes, f, should obey the n > 3f inequality, for a network of n nodes.
Consider an asynchronous network in a shared-memory environment consisting of n nodes. Assume that up to f of the nodes might be Byzantin (n > 12f), where the adversary is full-information and ...dynamic (sometimes called adaptive). In addition, the non-Byzantin nodes may undergo transient failures. Nodes advance in atomic steps, which consist of reading all registers, performing some calculation and writing to all registers.
The three main contributions of the paper are: first, the clock-function problem is defined, which is a generalization of the clock synchronization problem. This generalization encapsulates previous clock synchronization problem definitions while extending them to the current paper’s model. Second, a randomized asynchronous self-stabilizing Byzantin tolerant clock synchronization algorithm is presented.
In the construction of the clock synchronization algorithm, a building block that ensures different nodes advance at similar rates is developed. This feature is the third contribution of the paper. It is self-stabilizing and Byzantin tolerant and can be used as a building block for different algorithms that operate in an asynchronous self-stabilizing Byzantin model.
The convergence time of the presented algorithm is exponential. Observe that in the asynchronous setting the best known full-information dynamic Byzantin agreement also has an expected exponential convergence time.
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