scholarly journals Proving Opacity of Transactional Memory with Early Release

2015 ◽  
Vol 40 (4) ◽  
pp. 317-335
Author(s):  
Konrad Siek ◽  
Paweł T. Wojciechowski
Keyword(s):  
Shared Memory ◽  
Gold Standard ◽  
Concurrency Control ◽  
Transactional Memory ◽  
The Other ◽  
Proof Technique ◽  
Safety Properties ◽  
Optimistic Concurrency Control ◽  
Early Release ◽  
Low Level

Abstract Transactional Memory (TM) is an alternative way of synchronizing concurrent accesses to shared memory by adopting the abstraction of transactions in place of low-level mechanisms like locks and barriers. TMs usually apply optimistic concurrency control to provide a universal and easy-to-use method of maintaining correctness. However, this approach performs a high number of aborts in high contention workloads, which can adversely affect performance. Optimistic TMs can cause problems when transactions contain irrevocable operations. Hence, pessimistic TMs were proposed to solve some of these problems. However, an important way of achieving efficiency in pessimistic TMs is to use early release. On the other hand, early release is seemingly at odds with opacity, the gold standard of TM safety properties, which does not allow transactions to make their state visible until they commit. In this paper we propose a proof technique that makes it possible to demonstrate that a TM with early release can be opaque as long as it prevents inconsistent views.

scholarly journals STM: Lock-Free Synchronization

2014 ◽  
pp. 206-212
Author(s):  
Ryan Saptarshi Ray
Keyword(s):  
Parallel Programming ◽  
Shared Memory ◽  
Concurrency Control ◽  
Control Mechanism ◽  
Parallel Processors ◽  
Software Transactional Memory ◽  
New Approach ◽  
Low Level ◽  
Complex Interactions ◽  
Design Program

Current parallel programming uses low-level programming constructs like threads and explicit synchronization (for example, locks, semaphores and monitors) to coordinate thread execution which makes these programs difficult to design, program and debug. In this paper we present Software Transactional Memory (STM) which is a promising new approach for programming in parallel processors having shared memory. It is a concurrency control mechanism that is widely considered to be easier to use by programmers than other mechanisms such as locking. It allows portions of a program to execute in isolation, without regard to other, concurrently executing tasks. A programmer can reason about the correctness of code within a transaction and need not worry about complex interactions with other, concurrently executing parts of the program.

BIOCHEMICAL STUDIES ON SOCKEYE SALMON DURING SPAWNING MIGRATION: IV. THE NON-PROTEIN NITROGENOUS CONSTITUENTS OF THE MUSCLE

1958 ◽  
Vol 36 (8) ◽  
pp. 833-838 ◽  
Author(s):  
J. D. Wood
Keyword(s):  
Sockeye Salmon ◽  
The Other ◽  
Spawning Migration ◽  
Female Fish ◽  
Male And Female ◽  
Low Level ◽  
Early Stages ◽  
Biochemical Studies

The non-protein nitrogenous constituents of muscle of migrating sockeye salmon were investigated. These constituents were found to be the same in both male and female fish and were present in approximately the same amounts in both sexes. The histidine content of the muscle in all fish decreased to one fifth of the original value during the early stages of the migratory journey and remained at the low level thereafter. Some of the other constituents changed to a smaller extent, usually increasing in the later stages of the migration. This was especially noticeable in female fish. However, the increase in the concentration of these constituents in the muscle was due to a decrease in the amount of muscle in the fish rather than to an increase in the amounts of the compounds themselves.

Stimulation Seeking Throughout Seven Days of Sensory Deprivation

1967 ◽  
Vol 25 (1) ◽  
pp. 261-271 ◽  
Author(s):  
Seward Smith ◽  
Thomas I. Myers ◽  
Eugene Johnson
Keyword(s):  
Sensory Deprivation ◽  
The Other ◽  
Control Group ◽  
Early Release ◽  
Enlisted Men ◽  
Over Time

60 volunteer Naval enlisted men participated in a study of 7-day, individual isolation. 40 Ss lived in small, dark, quiet rooms with little to do (SD). The other 20 served in a live-in-the-lab control group (C) with ad lib. access to lights, recreational materials, and intercom conversation with another C S if mutually desired. 19 SD Ss, but only 1 C S, requested early release. Pre-, during-, and post-isolation tests were given. In a test of stimulation seeking, boring stock reports could be heard during a 1-hr. period on each of Days 1, 4, and 7 of isolation. SD Ss selected to listen significantly more than Cs on Days 4 and 7, with the differences increasing over time. Day 1 listening (about 6 hr. after isolation began) predicted who would later request release. In the discussion, currently available stimulation-seeking data are summarized and integrated.

scholarly journals Evaluation of Resistance Development in Bemisia tabaci Genn. (Homoptera: Aleyrodidae) in Cotton against Different Insecticides

Insects ◽  
2021 ◽  
Vol 12 (11) ◽  
pp. 996
Author(s):  
Muhammad Zaryab Khalid ◽  
Sohail Ahmed ◽  
Ibrahim Al-ashkar ◽  
Ayman EL Sabagh ◽  
Liyun Liu ◽  
...  
Keyword(s):  
Bemisia Tabaci ◽  
The Other ◽  
Resistance Development ◽  
Susceptible Population ◽  
Low Level ◽  
Development Of Resistance ◽  
Major Pest ◽  
Selection For ◽  
High Level ◽  
Very High

Cotton is a major crop of Pakistan, and Bemisia tabaci (Homoptera: Aleyrodidae) is a major pest of cotton. Due to the unwise and indiscriminate use of insecticides, resistance develops more readily in the whitefly. The present study was conducted to evaluate the resistance development in the whitefly against the different insecticides that are still in use. For this purpose, the whitefly population was selected with five concentrations of each insecticide, for five generations. At G1, compared with the laboratory susceptible population, a very low level of resistance was observed against bifenthrin, cypermethrin, acetamiprid, imidacloprid, thiamethoxam, nitenpyram, chlorfenapyr, and buprofezin with a resistance ratio of 3-fold, 2-fold, 1-fold, 4-fold, 3-fold, 3-fold, 3-fold, and 3-fold, respectively. However, the selection for five generations increased the resistance to a very high level against buprofezin (127-fold), and to a high level against imidacloprid (86-fold) compared with the laboratory susceptible population. While, a moderate level of resistance was observed against cypermethrin (34-fold), thiamethoxam (34-fold), nitenpyram (30-fold), chlorfenapyr (29-fold), and acetamiprid (21-fold). On the other hand, the resistance was low against bifenthrin (18-fold) after selection for five generations. A very low level of resistance against the field population of B. tabaci, at G1, showed that these insecticides are still effective, and thus can be used under the field conditions for the management of B. tabaci. However, the proper rotation of insecticides among different groups can help to reduce the development of resistance against insecticides.

scholarly journals The Interdecadal Variations and Causes of the Relationship Between Autumn Precipitation Anomalies in Eastern China and SSTA Over the Southeastern Tropical Indian Ocean

2021 ◽  
Author(s):  
Liwei Huo ◽  
Zhaoyong Guan ◽  
Dachao Jin ◽  
Xi Liu ◽  
Xudong Wang ◽  
...  
Keyword(s):  
Indian Ocean ◽  
Eastern China ◽  
Tropical Indian Ocean ◽  
The Other ◽  
Drought Event ◽  
Low Level ◽  
Rainfall Anomalies ◽  
Precipitation Anomalies ◽  
The Relationship ◽  
Southeastern Tropical Indian Ocean

Abstract Eastern China has a large population with rapid development of the economy, where is the important crop producing region. In this region, the spatial and temporal distribution of autumn rainfall in Eastern China is uneven, which has important societal impact. Using the NCEP–NCAR reanalysis and other observational datasets, it is found that the spatial distribution of the first EOF mode of autumn rainfall anomalies in eastern China is consistent across the region, with significant interannual variabilities. Pronounced interdecadal variations are presented in the relationship between autumn rainfall anomalies in eastern China and sea-surface temperature anomalies (SSTA) over the southeastern tropical Indian Ocean (SETIO). The interdecadal changes have been analyzed by considering two epochs: one during 1979-2004 and the other during 2005-2019. It shows weak and insignificant correlations between the autumn rainfall anomalies in eastern China and SSTA over SETIO during the first epoch. On the other hand, they are remarkable and positively correlated with each other during the second epoch. The inter-decadal changes of the above relationship are related to the warming of SST over SETIO during the second epoch. It causes stronger low-level convergence and ascending motion over SETIO, with the co-occurrence of enhanced western Pacific subtropical high and anomalous abundant moisture over eastern China carried by a low-level southerly anomaly originating from the South China Sea. Simultaneously, the local Hadley circulation over eastern China becomes weak, corresponding to the anomalous ascending motion. The collaboration of anomalous water vapour transport and ascending motion strengthens the connection between the SETIO SSTA and the autumn precipitation anomalies in eastern China, and vice versa. In the boreal autumn of 2019, entire eastern China suffered extreme drought. It suggests that this drought event in eastern China is strongly affected by the negative SSTA over SETIO, which is consistent with the statistical results.

scholarly journals Does Activating Cultural Schemata Facilitate EFL Learners' Listening Comprehension?

2018 ◽  
Vol 10 (3) ◽  
pp. 252-260
Author(s):  
Soheil Mahmoudi
Keyword(s):  
Null Hypothesis ◽  
Listening Comprehension ◽  
The Other ◽  
Efl Learners ◽  
Low Level ◽  
Cultural Schemata ◽  
Audio Files ◽  
Iranian Students

This study tried to find the possible relationship between listeners' cultural schemata and its activation and their performance in EFL listening comprehension. The participants of this study were two groups of 37 Muslim Iranian students. Firstly, the students were divided into two groups of high and low proficiency. Then, they were exposed to two audio files, one about mosques and the other about cathedrals. In one of the classes the recording about the cathedrals was played first, but in the other the order was reversed. The collected data were inputted into the SPSS program. The null hypothesis of the study was whether listening to a culturally unfamiliar topic (cathedrals) can activate low-level learners’ schema of the culturally familiar topic (mosques). The hypothesis of the study was accepted implying that an unfamiliar text, even if it is conceptually similar, cannot activate a culturally familiar schema in the low-level students. This study has pedagogical implications for teaching listening comprehension.

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