Ecological processes that occur at global scales are amongthe most impressive natural phenomena o... more Ecological processes that occur at global scales are amongthe most impressive natural phenomena on Earth; theylink environments across the globe and capture the imagination of observers. For example, billions of North American birds, representing more than 400 species, migrate annually, often thousands of miles, frequently under the cov-er of darkness, between breeding and nonbreeding areas. There is an urgent need to understand global processes in order to mitigate threats from anthropogenic change. For example, human-made collision hazards are killing hundreds of millions of birds annually (Crawford and Engstrom 2001; Longcore, Rich, and Gauthreaux 2008), and direct and indi-rect habitat alteration is reducing stopover habitats vital for birds to refuel during migration (Bonter, Donovan, and Brooks 2009; Veltri and Klem 2005). Our ability to mitigate this anthropogenic mortality relies on a detailed under-standing of the magnitude and composition of migration in time and space so ...
In this paper we propose an improved approximation scheme for the Vector Bin Packing problem (VBP... more In this paper we propose an improved approximation scheme for the Vector Bin Packing problem (VBP), based on the combination of (near-)optimal solution of the Linear Programming (LP) relaxation and a greedy (modified first-fit) heuristic. The Vector Bin Packing problem of higher dimension (d ≥ 2) is not known to have asymptotic polynomial-time approximation schemes (unless P = NP). Our algorithm improves over the previously-known guarantee of (ln d + 1 + ǫ) by Bansal et al. [1] for higher dimensions (d > 2). We provide a θ(1) approximation scheme for certain set of inputs for any dimension d. More precisely, we provide a 2-OPT algorithm, a result which is irrespective of the number of dimensions d.
Manual debugging is a common productivity drain in the machine learning (ML) lifecycle. Identifyi... more Manual debugging is a common productivity drain in the machine learning (ML) lifecycle. Identifying underperforming training jobs requires constant developer attention and deep domain expertise. As state-of-the-art models grow in size and complexity, debugging becomes increasingly difficult. Just as unit tests boost traditional software development, an automated ML debugging library can save time and money. We present Amazon SageMaker Debugger, a machine learning feature that automatically identifies and stops underperforming training jobs. Debugger is a new feature of Amazon SageMaker that automatically captures relevant data during training and evaluation and presents it for online and offline inspection. Debugger helps users define a set of conditions, in the form of built-in or custom rules, that are applied to this data, thereby enabling users to catch training issues as well as monitor and debug ML model training in real-time. These rules save time and money by alerting the de...
This paper presents the different MANET routing types, introduces some specific routing algorithm... more This paper presents the different MANET routing types, introduces some specific routing algorithms, and draws a comparison between them. The paper focuses on the two main types of MANET routing, Table-Driven and On-Demand. It presents the Table-Driven DSDR protocol, and the On-Demand DSR protocol. The comparison will draw a spotlight on differences of performance in the categories overhead, availability and scalability. While Table-Driven protocols outperform On-Demand protocols on availability, as the MANET grows in size, the performance of Table-Driven protocols suffers as their rather large overhead worsens their scalability.
Daily total effective scattering area (reflectivity) of birds (square centimeters) per unit volum... more Daily total effective scattering area (reflectivity) of birds (square centimeters) per unit volume (cubic km) estimated at 12 weather surveillance radar (WSR) stations in the northeastern USA during the autumn of 2010 and 2011 within 37.5 km radius of each WSR station and up to a maximum altitude of 3 km above ground level
Weekly estimates of probability of occurrence for 142 migratory species within 37.5 km radius cir... more Weekly estimates of probability of occurrence for 142 migratory species within 37.5 km radius circles centered on 12 weather surveillance radar stations located in the northeastern USA . Estimates are derived from spatiotemporal exploratory models (STEM) with occurrence information from the eBird citizen science dataset for the combined period 2004 to 2011
Data from: Migration timing and its determinants for nocturnal migratory birds during autumn migration
1. Migration is a common strategy used by birds that breed in seasonal environments, and multiple... more 1. Migration is a common strategy used by birds that breed in seasonal environments, and multiple environmental and biological factors determine the timing of migration. How these factors operate in combination during autumn migration, which is considered to be under weaker time constraints relative to spring migration, is not clear. 2. Here, we examine the patterns and determinants of migration timing for nocturnal migrants during autumn migration in the north-eastern USA using nocturnal reflectivity data from 12 weather surveillance radar stations and modelled diurnal probability of occurrence for 142 species of nocturnal migrants. We first model the capacity of seasonal atmospheric conditions (wind and precipitation) and ecological productivity (vegetation greenness) to predict autumn migration intensity. We then test predictions, formulated under optimal migration theory, on how migration timing should be related to assemblage-level estimates of body size and total migration distance within the context of dietary guild (insectivore and omnivore) and level of dietary plasticity during autumn migration. 3. Our results indicate seasonal declines in ecological productivity delineate the beginning and end of peak migration, whose intensity is best predicted by the velocity of winds at migration altitudes. Insectivorous migrants departed earlier in the season and, consistent with our predictions, large-bodied and long-distance insectivorous migrants departed the earliest. Contrary to our predictions, large-bodied and some long-distance omnivorous migrants departed later in the season, patterns that were replicated in part by insectivorous migrants that displayed dietary plasticity during autumn migration. 4. Our findings indicate migration timing in the region is dictated by optimality strategies, modified based on the breadth and flexibility of migrant's foraging diets, with declining ecological productivity defining possible resource thresholds during which migration occurs when winds at migration altitudes are mild. These observations provide the basis to assess how avian migration strategies may be affected by adjustments in seasonal patterns of atmospheric circulation and ecological productivity that may occur under global climate change
Abstract—Cloud Platforms allow programmers to write ap-plications that run in the cloud, or use s... more Abstract—Cloud Platforms allow programmers to write ap-plications that run in the cloud, or use services from the Cloud, or both while abstracting the essence of scalability and distributed processing. With the emergence of Clouds as a nascent architecture, we need abstractions that support emerging programming models. In recent years, Cloud Computing has led to the design and developement of diverse programming models for Massive Data Processing and Compute Intensive Applications. We survey different programming models for the Cloud, including the popular MapReduce Model and others which improve upon its shortcomings. Further, we look at models which are promising alternatives to these parallel programming models.
1.Migration is a common strategy used by birds that breed in seasonal environments, and multiple ... more 1.Migration is a common strategy used by birds that breed in seasonal environments, and multiple environmental and biological factors determine the timing of migration. How these factors operate in combination during autumn migration, which is considered to be under weaker time constraints relative to spring migration, is not clear. 2.Here, we examine the patterns and determinants of migration timing for nocturnal migrants during autumn migration in the northeastern USA using nocturnal reflectivity data from 12 weather surveillance radar stations and modeled diurnal probability of occurrence for 142 species of nocturnal migrants. We first model the capacity of seasonal atmospheric conditions (wind and precipitation) and ecological productivity (vegetation greenness) to predict autumn migration intensity. We then test predictions, formulated under optimal migration theory, on how migration timing should be related to assemblage-level estimates of body size and total migration distanc...
BioOne Complete (complete.BioOne.org) is a full-text database of 200 subscribed and open-access t... more BioOne Complete (complete.BioOne.org) is a full-text database of 200 subscribed and open-access titles in the biological, ecological, and environmental sciences published by nonprofit societies, associations, museums, institutions, and presses.
Bird migration occurs at the largest of global scales, but monitoring such movements can be chall... more Bird migration occurs at the largest of global scales, but monitoring such movements can be challenging. In the US there is an operational network of weather radars providing freely accessible data for monitoring meteorological phenomena in the atmosphere. Individual radars are sensitive enough to detect birds, and can provide insight into migratory behaviors of birds at scales that are not possible using other sensors. Archived data from the WSR-88D network of US weather radars hold valuable and detailed information about the continent-scale migratory movements of birds over the last 20 years. However, significant technical challenges must be overcome to understand this information and harness its potential for science and conservation. We describe recent work on an AI system to quantify bird migration using radar data, which is part of the larger BirdCast project to model and forecast bird migration at large scales using radar, weather, and citizen science data.
Ecological processes that occur at global scales are amongthe most impressive natural phenomena o... more Ecological processes that occur at global scales are amongthe most impressive natural phenomena on Earth; theylink environments across the globe and capture the imagination of observers. For example, billions of North American birds, representing more than 400 species, migrate annually, often thousands of miles, frequently under the cov-er of darkness, between breeding and nonbreeding areas. There is an urgent need to understand global processes in order to mitigate threats from anthropogenic change. For example, human-made collision hazards are killing hundreds of millions of birds annually (Crawford and Engstrom 2001; Longcore, Rich, and Gauthreaux 2008), and direct and indi-rect habitat alteration is reducing stopover habitats vital for birds to refuel during migration (Bonter, Donovan, and Brooks 2009; Veltri and Klem 2005). Our ability to mitigate this anthropogenic mortality relies on a detailed under-standing of the magnitude and composition of migration in time and space so ...
In this paper we propose an improved approximation scheme for the Vector Bin Packing problem (VBP... more In this paper we propose an improved approximation scheme for the Vector Bin Packing problem (VBP), based on the combination of (near-)optimal solution of the Linear Programming (LP) relaxation and a greedy (modified first-fit) heuristic. The Vector Bin Packing problem of higher dimension (d ≥ 2) is not known to have asymptotic polynomial-time approximation schemes (unless P = NP). Our algorithm improves over the previously-known guarantee of (ln d + 1 + ǫ) by Bansal et al. [1] for higher dimensions (d > 2). We provide a θ(1) approximation scheme for certain set of inputs for any dimension d. More precisely, we provide a 2-OPT algorithm, a result which is irrespective of the number of dimensions d.
Manual debugging is a common productivity drain in the machine learning (ML) lifecycle. Identifyi... more Manual debugging is a common productivity drain in the machine learning (ML) lifecycle. Identifying underperforming training jobs requires constant developer attention and deep domain expertise. As state-of-the-art models grow in size and complexity, debugging becomes increasingly difficult. Just as unit tests boost traditional software development, an automated ML debugging library can save time and money. We present Amazon SageMaker Debugger, a machine learning feature that automatically identifies and stops underperforming training jobs. Debugger is a new feature of Amazon SageMaker that automatically captures relevant data during training and evaluation and presents it for online and offline inspection. Debugger helps users define a set of conditions, in the form of built-in or custom rules, that are applied to this data, thereby enabling users to catch training issues as well as monitor and debug ML model training in real-time. These rules save time and money by alerting the de...
This paper presents the different MANET routing types, introduces some specific routing algorithm... more This paper presents the different MANET routing types, introduces some specific routing algorithms, and draws a comparison between them. The paper focuses on the two main types of MANET routing, Table-Driven and On-Demand. It presents the Table-Driven DSDR protocol, and the On-Demand DSR protocol. The comparison will draw a spotlight on differences of performance in the categories overhead, availability and scalability. While Table-Driven protocols outperform On-Demand protocols on availability, as the MANET grows in size, the performance of Table-Driven protocols suffers as their rather large overhead worsens their scalability.
Daily total effective scattering area (reflectivity) of birds (square centimeters) per unit volum... more Daily total effective scattering area (reflectivity) of birds (square centimeters) per unit volume (cubic km) estimated at 12 weather surveillance radar (WSR) stations in the northeastern USA during the autumn of 2010 and 2011 within 37.5 km radius of each WSR station and up to a maximum altitude of 3 km above ground level
Weekly estimates of probability of occurrence for 142 migratory species within 37.5 km radius cir... more Weekly estimates of probability of occurrence for 142 migratory species within 37.5 km radius circles centered on 12 weather surveillance radar stations located in the northeastern USA . Estimates are derived from spatiotemporal exploratory models (STEM) with occurrence information from the eBird citizen science dataset for the combined period 2004 to 2011
Data from: Migration timing and its determinants for nocturnal migratory birds during autumn migration
1. Migration is a common strategy used by birds that breed in seasonal environments, and multiple... more 1. Migration is a common strategy used by birds that breed in seasonal environments, and multiple environmental and biological factors determine the timing of migration. How these factors operate in combination during autumn migration, which is considered to be under weaker time constraints relative to spring migration, is not clear. 2. Here, we examine the patterns and determinants of migration timing for nocturnal migrants during autumn migration in the north-eastern USA using nocturnal reflectivity data from 12 weather surveillance radar stations and modelled diurnal probability of occurrence for 142 species of nocturnal migrants. We first model the capacity of seasonal atmospheric conditions (wind and precipitation) and ecological productivity (vegetation greenness) to predict autumn migration intensity. We then test predictions, formulated under optimal migration theory, on how migration timing should be related to assemblage-level estimates of body size and total migration distance within the context of dietary guild (insectivore and omnivore) and level of dietary plasticity during autumn migration. 3. Our results indicate seasonal declines in ecological productivity delineate the beginning and end of peak migration, whose intensity is best predicted by the velocity of winds at migration altitudes. Insectivorous migrants departed earlier in the season and, consistent with our predictions, large-bodied and long-distance insectivorous migrants departed the earliest. Contrary to our predictions, large-bodied and some long-distance omnivorous migrants departed later in the season, patterns that were replicated in part by insectivorous migrants that displayed dietary plasticity during autumn migration. 4. Our findings indicate migration timing in the region is dictated by optimality strategies, modified based on the breadth and flexibility of migrant's foraging diets, with declining ecological productivity defining possible resource thresholds during which migration occurs when winds at migration altitudes are mild. These observations provide the basis to assess how avian migration strategies may be affected by adjustments in seasonal patterns of atmospheric circulation and ecological productivity that may occur under global climate change
Abstract—Cloud Platforms allow programmers to write ap-plications that run in the cloud, or use s... more Abstract—Cloud Platforms allow programmers to write ap-plications that run in the cloud, or use services from the Cloud, or both while abstracting the essence of scalability and distributed processing. With the emergence of Clouds as a nascent architecture, we need abstractions that support emerging programming models. In recent years, Cloud Computing has led to the design and developement of diverse programming models for Massive Data Processing and Compute Intensive Applications. We survey different programming models for the Cloud, including the popular MapReduce Model and others which improve upon its shortcomings. Further, we look at models which are promising alternatives to these parallel programming models.
1.Migration is a common strategy used by birds that breed in seasonal environments, and multiple ... more 1.Migration is a common strategy used by birds that breed in seasonal environments, and multiple environmental and biological factors determine the timing of migration. How these factors operate in combination during autumn migration, which is considered to be under weaker time constraints relative to spring migration, is not clear. 2.Here, we examine the patterns and determinants of migration timing for nocturnal migrants during autumn migration in the northeastern USA using nocturnal reflectivity data from 12 weather surveillance radar stations and modeled diurnal probability of occurrence for 142 species of nocturnal migrants. We first model the capacity of seasonal atmospheric conditions (wind and precipitation) and ecological productivity (vegetation greenness) to predict autumn migration intensity. We then test predictions, formulated under optimal migration theory, on how migration timing should be related to assemblage-level estimates of body size and total migration distanc...
BioOne Complete (complete.BioOne.org) is a full-text database of 200 subscribed and open-access t... more BioOne Complete (complete.BioOne.org) is a full-text database of 200 subscribed and open-access titles in the biological, ecological, and environmental sciences published by nonprofit societies, associations, museums, institutions, and presses.
Bird migration occurs at the largest of global scales, but monitoring such movements can be chall... more Bird migration occurs at the largest of global scales, but monitoring such movements can be challenging. In the US there is an operational network of weather radars providing freely accessible data for monitoring meteorological phenomena in the atmosphere. Individual radars are sensitive enough to detect birds, and can provide insight into migratory behaviors of birds at scales that are not possible using other sensors. Archived data from the WSR-88D network of US weather radars hold valuable and detailed information about the continent-scale migratory movements of birds over the last 20 years. However, significant technical challenges must be overcome to understand this information and harness its potential for science and conservation. We describe recent work on an AI system to quantify bird migration using radar data, which is part of the larger BirdCast project to model and forecast bird migration at large scales using radar, weather, and citizen science data.
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Papers by Jeffrey John