Latent based temporal optimization approach for improving the performance of collaborative filtering.

Recommendation systems suggest peculiar products to customers based on their past ratings, preferences, and interests. These systems typically utilize collaborative filtering (CF) to analyze customers' ratings for products within the rating matrix. CF suffers from the sparsity problem because a large number of rating grades are not accurately determined. Various prediction approaches have been used to solve this problem by learning its latent and temporal factors. A few other challenges such as latent feedback learning, customers' drifting interests, overfitting, and the popularity decay of products over time have also been addressed. Existing works have typically deployed either short or long temporal representation for addressing the recommendation system issues. Although each effort improves on the accuracy of its respective benchmark, an integrative solution that could address all the problems without trading off its accuracy is needed. Thus, this paper presents a Latent-based Temporal Optimization (LTO) approach to improve the prediction accuracy of CF by learning the past attitudes of users and their interests over time. Experimental results show that the LTO approach efficiently improves the prediction accuracy of CF compared to the benchmark schemes.

Alveolar restoration following rapid maxillary expansion with and without corticotomy: A microcomputed tomography study in sheep.

OBJECTIVE: This study examined bone microstructure restoration after rapid maxillary expansion (RME) with and without corticotomy over multiple retention periods. METHODS: Eighteen male Dorper sheep were randomly distributed into three groups (n = 6 each group): group 1, RME with corticotomy on the buccal and palatal sides; group 2, conventional RME treatment; and group 3, no treatment. Post-RME, trabecular bone microstructure and new bone formation were evaluated by using microcomputed tomography (microCT) and histomorphometry after a 4- or 12-week retention period. Intergroup differences in bone quality and bone remodeling were analyzed by using two-way analysis of variance with Bonferroni post-hoc test. RESULTS: The bone volume fraction (bone volume [BV]/total volume [TV]) values relative to the control in groups 1 and 2 were 54.40% to 69.88% after the 4-week retention period and returned to approximately 80% after the 12-week retention period. The pooled BV/TV values of the banded teeth in groups 1 and 2 were significantly lower than those of the control after the 4-week retention period (p < 0.05). However, after the 12-week retention period, the pooled BV/TV values in group 2 were significantly lower than those in groups 1 and 3 (p < 0.05). Histomorphological analysis showed that the new bone formation area in group 1 was approximately two to three times of those in group 2 and control. CONCLUSIONS: Corticotomy significantly enhanced the restoration of bone quality after the retention periods for banded teeth. This benefit might result from the increased new bone formation after corticotomy.

Alveolar restoration following rapid maxillary expansion with and without corticotomy: A microcomputed tomography study in sheep / 대한치과교정학회지

OBJECTIVE@#This study examined bone microstructure restoration after rapid maxillary expansion (RME) with and without corticotomy over multiple retention periods.@*METHODS@#Eighteen male Dorper sheep were randomly distributed into three groups (n = 6 each group): group 1, RME with corticotomy on the buccal and palatal sides; group 2, conventional RME treatment; and group 3, no treatment. Post-RME, trabecular bone microstructure and new bone formation were evaluated by using microcomputed tomography (microCT) and histomorphometry after a 4- or 12-week retention period. Intergroup differences in bone quality and bone remodeling were analyzed by using two-way analysis of variance with Bonferroni post-hoc test.@*RESULTS@#The bone volume fraction (bone volume [BV]/total volume [TV]) values relative to the control in groups 1 and 2 were 54.40% to 69.88% after the 4-week retention period and returned to approximately 80% after the 12-week retention period. The pooled BV/TV values of the banded teeth in groups 1 and 2 were significantly lower than those of the control after the 4-week retention period (p < 0.05). However, after the 12-week retention period, the pooled BV/TV values in group 2 were significantly lower than those in groups 1 and 3 (p < 0.05). Histomorphological analysis showed that the new bone formation area in group 1 was approximately two to three times of those in group 2 and control.@*CONCLUSIONS@#Corticotomy significantly enhanced the restoration of bone quality after the retention periods for banded teeth. This benefit might result from the increased new bone formation after corticotomy.

Effects of standardized quassinoid-rich Eurycoma longifolia extract in a rat model of osteoporosis due to testosterone deficiency: A densitometric, morphometric and biomechanical study.

BACKGROUND: Eurycoma longifolia (EL) is a well-known aphrodisiac herb for men. Recently, the crude extract of EL was reported to possess anti-osteoporotic activities. OBJECTIVE: This study aims to determine the bone protective effects of the standardized quassinoid-rich EL extract in testosterone-deficient rat model. METHODS: Ninety-six intact male Sprague-Dawley rats were randomized into baseline, sham, orchidectomized, and chemically castrated groups. Chemical castration was performed via subcutaneous injection of degarelix at 2 mg/kg. The orchidectomized and degarelix-induced rats were administered with vehicle, intramuscularly injected with testosterone once a week, or orally supplemented with EL extract at doses of 25 mg/kg, 50 mg/kg or 100 mg/kg daily for 10 weeks. Bone mass, microarchitecture and strength were analyzed by dual-energy x-ray absorptiometry (DEXA), micro-CT and three-point bending test. RESULTS: Whole body bone mineral density and femoral bone mineral content significantly increased in testosterone groups (p <  0.05). Micro-CT analysis revealed that trabecular bone volume, number, separation and connectivity density were significantly improved by testosterone administration. However, the structural model index was only improved in degarelix group supplemented with 100 mg/kg EL extract (P <  0.05). The improvement of cortical thickness by EL extract was similar to that of testosterone groups (p <  0.05). Biomechanically, EL extract supplementation was able to improve stiffness, strain and modulus of elasticity in degarelix-induced groups, while stress parameter was significantly improved in orchidectomized groups (p <  0.05). CONCLUSION: Quassinoid-rich EL extract enables to protect against bone loss due to testosterone deficiency. The protective effect on cortical thickness and biomechanical parameters is comparable to testosterone group.

Changes in pancreatic histology, insulin secretion and oxidative status in diabetic rats following treatment with Ficus deltoidea and vitexin.

BACKGROUND: The potential application of Ficus deltoidea and vitexin for the management of symptomatologies associated with diabetes mellitus (DM) has gained much attention. However, less firm evidence comes from data to augment our understanding of the role of F. deltoidea and vitexin in protecting pancreatic ß-cells. The aim of this study was to assess histological and oxidative stress changes in the pancreas of streptozotocin (STZ)-induced diabetic rats following F. deltoidea extract and vitexin treatment. METHODS: F. deltoidea and vitexin was administrated orally to six-weeks STZ-induced diabetic rats over 8 weeks period. The glucose and insulin tolerances were assessed by intraperitoneal glucose (2 g/kg) tolerance test (IPGTT) and intraperitoneal insulin (0.65 U/kg) tolerance test (IPITT), respectively. Subsequently, insulin resistance was assessed by homeostasis assessment model of insulin resistance (HOMA-IR), quantitative insulin sensitivity check index (QUICKI) and the insulin/triglyceride-derived McAuley index. The histological changes in the pancreas were then observed by hematoxylin-eosin (H&E) staining. Further, the pattern of fatty acid composition and infrared (IR) spectra of the serum and pancreas were monitored by gas chromatography (GC) method and Fourier Transform Infrared (FT-IR) spectroscopy. RESULTS: F. deltoidea and vitexin increased pancreatic antioxidant enzymes and promoted islet regeneration. However, a significant increase in insulin secretion was observed only in rats treated with F. deltoidea. More importantly, reduction of fasting blood glucose is consistent with reduced FT-IR peaks at 1200-1000 cm-1. CONCLUSIONS: These results accentuate that F. deltoidea and vitexin could be a potential agent to attenuate pancreatic oxidative damage and advocate their therapeutic potential for treating DM.

Evaluation of the thermal effects of prenatal ultrasound on hematological analysis of young Oryctolagus Cuniculus.

Elevated temperatures can induce changes in red blood cell (RBC), white blood cell (WBC) and platelet (PLT) counts. Ultrasound heating during obstetric scans has the potential to increase body temperature owing to the phenomenon of absorption. We conducted a study to determine the thermal effects of prenatal ultrasound on RBCs, hemoglobin concentration (Hb), WBCs and PLTs in young rabbits. We selected 69 rabbits that were 1 month of age and 73 that were 5 months of age, and allocated them to four groups. The control group consisted of four pregnant does that were allowed to have a full term delivery without any ultrasound exposure. The experimental groups were subjected to one-time ultrasound exposure for 30, 60 and 90 min in the middle of each gestational stage accordingly. RBCs and Hb showed significant reductions in the experimental groups of 1- and 5-month-old rabbits (P<0.05). In addition, WBCs and PLTs yielded significant differences in the 1-month group that were not observed in the 5-month group (P>0.05). The highest values recorded were those of the WBCs of 1-month-old subjects that received 90 min of exposure at the second stage of gestation. The PLTs were the lowest values recorded in 1-month-old subjects following 90 min of ultrasound exposure at the third stage of gestation. These findings suggest that hematological fluctuations during the early stages of postnatal life persisted until 1 month of age and recovered thereafter, as the subjects progressed into adulthood. Therefore, ultrasound heating can cause significant, yet reversible effects on the hematological parameters of rabbits.