Lock-Free and Practical Deques using Single-Word Compare-And-Swap

We present an efficient and practical lock-free implementation of a concurrent deque that is disjoint-parallel accessible and uses atomic primitives which are available in modern computer systems. Previously known lock-free algorithms of deques are either based on non-available atomic synchronization primitives, only implement a subset of the functionality, or are not designed for disjoint accesses. Our algorithm is based on a doubly linked list, and only requires single-word compare-and-swap atomic primitives, even for dynamic memory sizes. We have performed an empirical study using full implementations of the most efficient algorithms of lock-free deques known. For systems with low concurrency, the algorithm by Michael shows the best performance. However, as our algorithm is designed for disjoint accesses, it performs significantly better on systems with high concurrency and non-uniform memory architecture

Associations between postpartum fertility phenotypes and genetic traits in seasonal-calving, pasture-based lactating dairy cows

peer-reviewedThe objective of this study was to evaluate the associations between corpus luteum (CL) status, uterine health, body condition score (BCS), metabolic status, and parity at wk 3 and 7 postpartum in seasonal-calving, pasture-based, lactating dairy cows. The associations between those phenotypes and individual genetic traits were also evaluated. First- and second-parity spring-calving lactating dairy cows (n = 2,600) from 35 dairy farms in Ireland were enrolled. Farms were visited every 2 weeks; cows that were at wk 3 (range 14 to 27 DIM) and wk 7 (range 42 to 55 DIM) postpartum were examined. Body condition score was measured using a scale of 1 to 5 with 0.25 increments. Transrectal ultrasound examination was performed at wk 3 and 7 postpartum to determine presence or absence of CL and ultrasound reproductive tract score. Blood samples were collected at each visit and the concentrations of glucose, β-hydroxybutyrate (BHB), and fatty acids (FA) were analyzed by using enzymatic colorimetry. Cows were grouped into 3 BCS categories [low (≤2.5), target (≥2.75 and ≤3.25), and high (≥3.5)]; 2 CL status categories: (present or absent); 2 uterine health status (UHS) categories (normal and abnormal); and 3 metabolic status categories [good (high glucose, low fatty acids and BHB), poor (low glucose, high fatty acids and BHB), and moderate (all other combinations)]. Fisher's exact test was used to test associations between variables and was supplemented by logistic regression. We found associations between UHS (wk 3 and 7), BCS (wk 3 and 7), parity (wk 3 and 7) metabolic status (wk 3), and predicted transmitting ability for calving interval (PTA for CIV; wk 3) and CL status. Cows that had abnormal UHS, low BCS, primiparity, and poor metabolic status, and were in the quartile with the greatest PTA for CIV were less likely to have had CL present at wk 3 and 7 postpartum. We also found associations between CL status (wk 3 and 7), BCS (wk 3 and 7), parity (wk 3 and 7), and PTA for CIV (wk 3) and UHS. Cows that did not have a CL present had low BCS, primiparity, and that were in the quartile with greatest PTA for CIV, had a greater risk of abnormal UHS at wk 3 and 7 postpartum. We observed strong associations between CL status, UHS, BCS, metabolic status, parity, and individual genetic traits at wk 3 and 7 postpartum in seasonal-calving, pasture-based lactating dairy cows. Achieving target BCS and good metabolic status, and selecting cows based on PTA for CIV, are all expected to increase the likelihood of hastening the resumption of estrous cyclicity and enhancing uterine health during the postpartum period

Associations between postpartum phenotypes, cow factors, genetic traits, and reproductive performance in seasonal-calving, pasture-based lactating dairy cows

peer-reviewedThe objective of this study was to evaluate associations between corpus luteum (CL) status, uterine health, body condition score (BCS), metabolic status, parity, genetic merit for fertility traits, and reproductive performance in pasture-based dairy cows managed for seasonal reproduction. First- and second-lactation (n = 2,600) spring-calving dairy cows from 35 dairy farms located in Ireland were enrolled in the study. Farms were visited every 2 wk, and animals that were at wk 3 (range: 14–27 d in milk) and wk 7 (range: 42–55 d in milk) postpartum were examined. Body condition score was measured using a 1-to-5 scale in 0.25-point increments. Transrectal ultrasound examination was performed at wk 3 and 7 postpartum to determine presence or absence of CL and ultrasound reproductive tract score (scale of G1–G4). Blood samples were collected at each visit, and the concentrations of glucose, β-hydroxybutyrate (BHB), and fatty acids (FA) were analyzed using enzymatic colorimetry. Animals were grouped into 3 BCS categories [low (≤2.5), target (2.75–3.25), and high (≥3.5)], 2 CL categories (present or absent), 2 uterine health status categories (normal or abnormal), and 3 metabolic status categories [good (high glucose, low FA and BHB), poor (low glucose, high FA and BHB), and moderate (all other combinations)]. Fisher's exact test was used to test for associations between variables and was supplemented by logistic regression. More cows with a CL at wk 7 were served during the first 21 d of the breeding period compared with cows without a CL. Cows classified as having a uterine score of G3 or G4 at wk 3 and 7 had lower odds of pregnancy establishment during the breeding period compared with animals with a uterine score of G1 or G2. Animals with low BCS at wk 7 had lower odds of pregnancy establishment than cows with a target BCS. Cows classified as having good metabolic status at both wk 3 and wk 7 had greater odds of pregnancy establishment during the first 21 d of the breeding season than those classified as having poor metabolic status. Overall, primiparous cows had greater reproductive performance than second-parity cows. Animals in the quartiles with the best predicted transmitting ability for survival and calving interval had better reproductive performance compared with animals in the other quartiles. Cows that had better genetic merit for fertility traits and good metabolic status, achieved target BCS, and had a favorable ultrasound reproductive tract score and a CL present at wk 7 postpartum had superior reproductive performance

Lock-Free and Practical Doubly Linked List-Based Deques Using Single-Word Compare-and-Swap

We present an efficient and practical lock-free implementation of a concurrent deque that supports parallelism for disjoint accesses and uses atomic primitives which are available in modern computer systems. Previously known lock-free algorithms of deques are either based on non-available atomic synchronization primitives, only implement a subset of the functionality, or are not designed for disjoint accesses. Our algorithm is based on a general lock-free doubly linked list, and only requires single-word compare-and-swap atomic primitives. It also allows pointers with full precision, and thus supports dynamic deque sizes. We have performed an empirical study using full implementations of the most efficient known algorithms of lock-free deques. For systems with low concurrency, the algorithm by Michael shows the best performance. However, as our algorithm is designed for disjoint accesses, it performs significantly better on systems with high concurrency and non-uniform memory architecture. In addition, the proposed solution also implements a general doubly linked list, the first lock-free implementation that only needs the single-word compare-and-swap atomic primitive

Lock-Free and Practical Doubly Linked List-Based Deques using Single-Word Compare-And-Swap

We present an efficient and practical lock-free implementation of a concurrent deque that supports parallelism for disjoint accesses and uses atomic primitives which are available in modern computer systems. Previously known lock-free algorithms of deques are either based on non-available atomic synchronization primitives, only implement a subset of the functionality, or are not designed for disjoint accesses. Our algorithm is based on a general lock-free doubly linked list, and only requires single-word compare-and-swap atomic primitives. It also allows pointers with full precision, and thus supports dynamic deque sizes. We have performed an empirical study using full implementations of the most efficient known algorithms of lock-free deques. For systems with low concurrency, the algorithm by Michael shows the best performance. However, as our algorithm is designed for disjoint accesses, it performs significantly better on systems with high concurrency and non-uniform memory architecture. In addition, the proposed solution also implements a general doubly linked list, the first lock-free implementation that only needs the single-word compare-and-swap atomic primitive

A Dynamic Elimination-Combining Stack Algorithm

Two key synchronization paradigms for the construction of scalable concurrent data-structures are software combining and elimination. Elimination-based concurrent data-structures allow operations with reverse semantics (such as push and pop stack operations) to "collide" and exchange values without having to access a central location. Software combining, on the other hand, is effective when colliding operations have identical semantics: when a pair of threads performing operations with identical semantics collide, the task of performing the combined set of operations is delegated to one of the threads and the other thread waits for its operation(s) to be performed. Applying this mechanism iteratively can reduce memory contention and increase throughput. The most highly scalable prior concurrent stack algorithm is the elimination-backoff stack. The elimination-backoff stack provides high parallelism for symmetric workloads in which the numbers of push and pop operations are roughly equal, but its performance deteriorates when workloads are asymmetric. We present DECS, a novel Dynamic Elimination-Combining Stack algorithm, that scales well for all workload types. While maintaining the simplicity and low-overhead of the elimination-bakcoff stack, DECS manages to benefit from collisions of both identical- and reverse-semantics operations. Our empirical evaluation shows that DECS scales significantly better than both blocking and non-blocking best prior stack algorithms

Effects of synchronization treatments on ovarian follicular dynamics, corpus luteum growth, and circulating steroid hormone concentrations in lactating dairy cows

Lactating dairy cows (n = 57) >= 45 d postpartum at first service were enrolled in a randomized complete block design study to evaluate treatments to synchronize estrus and ovulation. At 10 d before artificial insemination (AI), animals were randomly assigned to 1 of 3 treatments: (1) d - 10 GnRH (GnRH1; 10 mu g of buserelin, i.m.) and controlled internal drug release insert [CIDR, 1.38 g of progesterone (P4)]; d - 3 PGF(2 alpha) (PGF; 25 mg of dinoprost, i.m.); d - 2 CIDR out; and AI at observed estrus (CIDR_OBS); (2) same as CIDR_OBS, but GnRH (GnRH2) 36 h after CIDR out and timed AI (TAI) 18 h later (CIDR_TAI); or (3) same as CIDR_TAI, but no CIDR (Ovsynch). Transrectal ultrasound was used to assess follicle size before ovulation and on d 4, 8, and 15 after the presumptive day of estrus (d 0) to measure the corpus luteum (CL). Blood samples were collected to determine concentrations of estradiol (E2; d - 10, - 9, - 3, - 2, - 1, and 0) and P4 (d - 10, - 9, - 2, - 1, 0, 1, 4, 6, 8, 11, and 15). No treatment differences were observed in either circulating concentrations of P4 or the ovulatory response to GnRH1 at the onset of synchronization treatments. Circulating concentrations of P4 were greater for CIDR_OBS and CIDR_TAI compared with Ovsynch at 24 h after CIDR insertion (5.34 and 4.98 vs. 1.75 ng/mL) and immediately before CIDR removal (1.65 and 1.48 vs. 0.40 ng/mL). Peak circulating concentrations of E2 were greater for CIDR_OBS compared with Ovsynch (3.85 vs. 2.39 pg/mL), but CIDR_TAI (2.82 pg/mL) did not differ from either CIDR_OBS or Ovsynch. The interval from PGF injection to peak circulating E2 did not differ between CIDR_TAI and Ovsynch (52.1 vs. 49.8 h). Both CIDR_TAI and Ovsynch, however, had shorter intervals from PGF injection to peak circulating E2 concentrations compared with CIDR_OBS (67.8 h). The diameter of the dominant follicle before ovulation was greater for CIDR_OBS compared with Ovsynch (18.5 vs. 16.0 mm) but CIDR_TAI (17.1 mm) did not differ from either of the other treatments. The mean interval from PGF to ovulation was longer for CIDR_OBS (100.0 h) compared with CIDR_TAI and Ovsynch (84.4 and 83.2 h, respectively). Use of CIDR_OBS resulted in increased preovulatory follicle size and greater circulating concentrations of E2 due to a longer period of preovulatory follicle growth. Progesterone supplementation during synchronization and GnRH on the day before TAI affected ovulatory follicle size, and periovulatory circulating concentrations of P4 and E2. No differences, however, in postovulatory P4 or luteal volume profiles were observed