Fast Matrix Factorization for Online Recommendation with Implicit Feedback

This paper contributes improvements on both the effectiveness and efficiency of Matrix Factorization (MF) methods for implicit feedback. We highlight two critical issues of existing works. First, due to the large space of unobserved feedback, most existing works resort to assign a uniform weight to the missing data to reduce computational complexity. However, such a uniform assumption is invalid in real-world settings. Second, most methods are also designed in an offline setting and fail to keep up with the dynamic nature of online data. We address the above two issues in learning MF models from implicit feedback. We first propose to weight the missing data based on item popularity, which is more effective and flexible than the uniform-weight assumption. However, such a non-uniform weighting poses efficiency challenge in learning the model. To address this, we specifically design a new learning algorithm based on the element-wise Alternating Least Squares (eALS) technique, for efficiently optimizing a MF model with variably-weighted missing data. We exploit this efficiency to then seamlessly devise an incremental update strategy that instantly refreshes a MF model given new feedback. Through comprehensive experiments on two public datasets in both offline and online protocols, we show that our eALS method consistently outperforms state-of-the-art implicit MF methods. Our implementation is available at https://github.com/hexiangnan/sigir16-eals.Comment: 10 pages, 8 figure

Scout first-generation bean leaf beetles now

Bean leaf beetle feeding on soybean pods can lead to significant reductions in seed quality and yield. Management during the pod setting and filling stages can be frustrating because beetles may feed on pods for a couple of weeks before the population reaches the economic threshold. In this situation, some loss in seed quality and quantity occurs before an insecticide application can be economically justified. Larry Pedigo and his students at Iowa State University have developed research-based information to help make a management decision for second-generation bean leaf beetles based upon the population size of the first-generation bean leaf beetles

Scouting for alfalfa weevil larvae

Degree-day information indicates that alfalfa weevil larvae have hatched throughout much of southern and central Iowa. Proper management of this insect requires timely scouting, correct identification, determination of population levels, and if necessary, cultural or chemical control. Fields should be scouted for alfalfa weevils because the larvae can be very destructive to first-cutting alfalfa. They remove leaf tissue, beginning with the new leaves at the top of the plant, and then work down the stem to other leaves. This feeding reduces forage quality and quantity

Good News—Bean Leaf Beetles Hit Hard by Winter Cold

During the last 20 years, the bean leaf beetle has undergone tremendous population changes in Iowa. From 1989 to 1996, the populations (both first generation and second generation) were relatively insignificant and the insect was not considered to be a serious pest. But in 1997, the population in central Iowa began a yearly escalation until it reached a historical high in 2002. Populations that year were nearly 400 times larger than those of the mid-1990s and we believe that this was due in part to milder winters followed by earlier planting of soybeans. Since that time, the population has returned to more normal levels and is similar to what we witnessed at the beginning of the beetle explosion in the late 1990s

Bean leaf beetle: Predicted peak first-generation dates

Bean leaf beetle feeding on soybean pods can lead to significant reductions in seed quality and yield. Management during the pod setting and filling stages can be frustrating because beetles may feed on pods for a couple of weeks before the population reaches the economic threshold. In this situation, some loss in seed quality and quantity occurs before an insecticide application can be economically justified. Several years ago, Larry Pedigo and his students in the Department of Entomology developed research-based information to help make a management decision for second-generation bean leaf beetles based upon the population size of the first-generation bean leaf beetles

Predicting first-generation bean leaf beetles

Bean leaf beetle feeding on soybean pods can lead to significant reductions in seed quality and yield. Management during the pod setting and filling stages can be frustrating because beetles may feed on pods for a couple of weeks before the population reaches the economic threshold. In this situation, some loss in seed quality and quantity occurs before an insecticide application can be economically justified. Several years ago, Larry Pedigo, a lecturer in the Department of Entomology, and his students developed research-based information to help make a management decision for second-generation bean leaf beetles based upon the population size of the first-generation bean leaf beetles

Alfalfa weevil scouting and thresholds

Degree-day information indicates that alfalfa weevil larvae have hatched throughout much of southern Iowa (see map). Proper management of this insect requires timely scouting, correct identification, determination of population levels, and if necessary, cultural or chemical control. Fields should be scouted for alfalfa weevils because the larvae can be very destructive to first cutting alfalfa. They remove leaf tissue, beginning with the new leaves at the top of the plant, and then work down the stem to other leaves. This feeding reduces forage quality and quantity

Stalk Borers Set to Invade Border Rows

Stalk borers are notorious for killing or stunting corn rows next to fences, grassed waterways and conservation terraces. To stop this damage, fields must be scouted and an insecticide applied on a timely basis before the larvae have an opportunity to tunnel into the growing point of the young plants

Bean leaf beetles: Predicted winter mortality

During the last 17 years, the bean leaf beetle has undergone tremendous population changes in Iowa. From 1989 to 1996, the populations (both first generation and second generation) were relatively insignificant and the insect hardly could even be considered a serious pest. But in 1997, the population in central Iowa began to accelerate nearly yearly until it reached a historical high in 2002. Populations that year were nearly 400 times larger than those of the mid-1990s. Since that time, the population has returned to more normal levels and is similar to what we witnessed at the beginning of the beetle explosion in the late 1990s