Abstract: A system partitions a graph representation of relationships between block devices and associated snapshots into a plurality of cells to more evenly distribute computing resource usage attributable to the block devices and snapshots. The relationships may be analyzed to determine resource usage associated with the block devices and/or the snapshots wherein the resource usage corresponds to a mutation operation rate or number of mutation operations performed (or scheduled for performance). As a result of determining that the resource usage for a given cell exceeds a predetermined threshold for resource usage, the cell may be partitioned into a plurality of cells, and a portion of the corresponding block device(s), and subsequent snapshot(s) generated therefrom, may be assigned to the new cell.

Abstract: A metrics subsystem determines the utilization of computing resources of server computer systems. The metrics subsystem may obtain metadata associated with a plurality of computing resources used to provide a service. The metrics subsystem determines a set of references to data included in the metadata and aggregates references of the set of references to determine utilization of computing resources and provides the utilization to a metering service.

Abstract: A router of a block-level data storage service receives a request to generate a snapshot of a block device. The router, based on routing metadata for the block-level data storage service, identifies active metadata that indicates a first cell that may maintain the block device and alternate metadata that indicates a second cell that may maintain the block device. Based on a first state of the block device in the first cell, a second state of the block device in the second cell, and a predetermined set of rules defining operations corresponding to outcomes associated with the first state and the second state, the router determines which of the first cell and the second cell authoritatively maintains the block device. The router transmits the request to the appropriate cell in accordance with the predetermined set of rules.

Abstract: A computing system that provides virtual computing services may generate and manage remote computing sessions between client computing devices and virtual desktop instances hosted on the service provider's network. A computing resource instance manager may monitor connections to and disconnections from a virtual desktop instance during particular time periods, and may apply a resource management policy to determine whether and when to shut down an underlying virtualized computing resource instance following a disconnection (e.g., immediately, after some period of time, or only between certain hours). A storage volume for the virtual desktop instance may be detached during a shutdown. In response to a reconnection request, the virtualized computing resource instance (or another such instance) may be restarted and the storage volume may be reattached. The computing resource instance manager may develop a model for predicting when to shut down or restart an instance based on historical data or machine learning.

Abstract: Generally described, one or more aspects of the present application correspond to techniques for creating encrypted block store volumes of data from unencrypted object storage snapshots of the volumes. These encryption techniques use a special pool of servers for performing the encryption. These encryption servers are not accessible to users, and they perform encryption and pass encrypted volumes to other block store servers for user access. The encryption context for the volumes can be persisted on the encryption severs for as long as needed for encryption and not shared with the user-facing servers in order to prevent user access to encryption context.

Abstract: A system (10) and a method (100) iteratively reconstruct an image of a target volume of a subject. In each iteration of a plurality of iterations, an estimate image of the target volume (54) is forward projected (58) and compared (62) to received event data (44) to determine a discrepancy (64). The discrepancy (64) is back projected (66) and the back projection (68) updates (70) the estimate image (54). In at least one iteration, the estimate image (54) is filtered (52) in the image domain prior to being back projected.

Abstract: A computing system that provides virtual computing services may generate and manage remote computing sessions between client computing devices and virtual desktop instances hosted on the service provider's network. A computing resource instance manager may monitor connections to and disconnections from a virtual desktop instance during particular time periods, and may apply a resource management policy to determine whether and when to shut down an underlying virtualized computing resource instance following a disconnection (e.g., immediately, after some period of time, or only between certain hours). A storage volume for the virtual desktop instance may be detached during a shutdown. In response to a reconnection request, the virtualized computing resource instance (or another such instance) may be restarted and the storage volume may be reattached. The computing resource instance manager may develop a model for predicting when to shut down or restart an instance based on historical data or machine learning.

Abstract: A thermal impedance amplifier includes: a resistive layer including: a resistance member; a first electrode in electrical communication with the resistance member; and a second electrode in electrical communication with the resistance member; a switch layer opposing the resistive layer and including: a switch member; a first switch electrode in electrical communication with the switch member; and a second switch electrode in electrical communication with the switch member, the switch member: switching from a first resistance to a second resistance in response to receiving phonons from the resistance member, being superconductive at the first resistance, and producing an amplified voltage in response to being at the second resistance; and a thermal conductor interposed between the resistance member and the switch member.

Abstract: Methods, systems, and computer-readable media for management of virtual desktop instance pools are disclosed. A plurality of virtual desktop instances are provisioned in a pool for a client organization. The number of virtual desktop instances does not exceed a number of virtual desktop slots for the client organization. To a first client device associated with a first user, access is provided to a particular virtual desktop instance based (at least in part) on a determination that a current number of connected virtual desktop instances is less than the number. To a second client device associated with a second user, access is denied to the plurality of virtual desktop instances based (at least in part) on a determination that a current number of connected virtual desktop instances meets the number.

Abstract: Systems and methods for geographic-aware virtual desktops are disclosed. In one example, a pool of network addresses can be maintained. Each network address can be associated with a respective geographical location. The pool of network addresses can include network addresses associated with different respective geographical locations. A geographical location associated with a client device accessing a virtual desktop can be determined. An external-facing network address can be selected from the pool of network addresses based on the geographical location associated with the client device. The external-facing network address can be assigned for network traffic associated with the virtual desktop.

Abstract: Methods, systems, and computer-readable media for management of virtual desktop instance pools are disclosed. A plurality of virtual desktop instances are provisioned in a pool for a client organization. The number of virtual desktop instances does not exceed a number of virtual desktop slots for the client organization. To a first client device associated with a first user, access is provided to a particular virtual desktop instance based (at least in part) on a determination that a current number of connected virtual desktop instances is less than the number. To a second client device associated with a second user, access is denied to the plurality of virtual desktop instances based (at least in part) on a determination that a current number of connected virtual desktop instances meets the number.

Abstract: Methods, systems, and computer-readable media for management of virtual desktop instance pools are disclosed. A plurality of virtual desktop instances are provisioned in a pool for a client organization. The number of virtual desktop instances does not exceed a number of virtual desktop slots for the client organization. To a first client device associated with a first user, access is provided to a particular virtual desktop instance based (at least in part) on a determination that a current number of connected virtual desktop instances is less than the number. To a second client device associated with a second user, access is denied to the plurality of virtual desktop instances based (at least in part) on a determination that a current number of connected virtual desktop instances meets the number.

Abstract: A computing system that provides virtual computing services may generate and manage remote computing sessions between client computing devices and virtual desktop instances hosted on the service provider's network. A computing resource instance manager may monitor connections to and disconnections from a virtual desktop instance during particular time periods, and may apply a resource management policy to determine whether and when to shut down an underlying virtualized computing resource instance following a disconnection (e.g., immediately, after some period of time, or only between certain hours). A storage volume for the virtual desktop instance may be detached during a shutdown. In response to a reconnection request, the virtualized computing resource instance (or another such instance) may be restarted and the storage volume may be reattached. The computing resource instance manager may develop a model for predicting when to shut down or restart an instance based on historical data or machine learning.

Abstract: An apparatus includes a base layer; and a superconducting nanowire disposed on the base layer in a continuous meander pattern and including an amorphous metal-metalloid alloy such that the apparatus is configured to detect single photons, and the continuous meander pattern includes: a plurality of parallel line segments; and a plurality of curved segments, wherein adjacent parallel line segments are joined by a curved segment.

Abstract: A system (10) and a method (100) iteratively reconstruct an image of a target volume of a subject. In each iteration of a plurality of iterations, an estimate image of the target volume (54) is forward projected (58) and compared (62) to received event data (44) to determine a discrepancy (64). The discrepancy (64) is back projected (66) and the back projection (68) updates (70) the estimate image (54). In at least one iteration, the estimate image (54) is filtered (52) in the image domain prior to being back projected.

Abstract: A method for selecting a communication protocol for a virtual desktop instance in a service provider environment may include providing to a client computing device, access to a virtual desktop instance running on a server computer using a first communication channel associated with a first communication protocol. A request for functionality from a user of the device is detected, the requested functionality being unsupported by the first communication protocol. A second communication protocol from a plurality of available communication protocols may be selecting based on the requested functionality. The second communication protocol may support the requested functionality. A user authorization for using the second communication protocol can be verified.

Abstract: A user of a computing device selects a data file and, through an input device, transmits a command to open the selected data file. In response, the computing device launches a location determination application determines, based at least in part on a policy associated with a file type corresponding to the selected data file, that the data file is to be opened in a virtual computing environment. The computing device provides the selected data file to the virtual computing environment along with one or more executable instructions that may cause a server to launch an application within the virtual computing environment capable of opening the selected data file. The user of the computing device, through a virtual computing environment interface installed on the computing device, may access the virtual computing environment to use the selected data file.

Abstract: A superconducting nanowire single photon detector (SN-SPD) microelectronic circuit is described which has higher quantum efficiency and signal-to-noise than any SN-SPD's known in the art. The material and configuration of the microelectronic circuit eliminates the polarization dependence and shows improved signal-to-noise over SN-SPD microelectronic circuits known in the art. The higher efficiency, polarization independence, and high signal-to-noise is achieved by vertically stacking two tungsten-silicide (TS) SN-SPDs and electrically connecting them in parallel. This structure forms a multilayer superconducting nanowire avalanche photo-detector (SNAP). A single photon detection device employing the multilayer (SNAP) microelectronic circuit demonstrates a peak system detection efficiency of 87.7% and a polarization dependence of less than 2%. This represents nearly an order of magnitude improvement in both system detection efficiency and reduction of polarization dependence compared to conventional SNSPDs.

Abstract: A nuclear medicine scanner system (1) includes an intelligent scheduler (2) which schedules a plurality of patients, each for an ordered nuclear medicine scanning procedure with a nuclear medicine scanning device (4) based on data mined from prior patients with like scanning procedures and in a time window which minimizes the patient dose.

Abstract: Methods and systems for determining a memory access time are provided. A first phase skew is measured between a first clock signal used by a memory and a second clock signal used as a reference clock signal. Then, a second phase skew is measured between a delayed version of the first clock signal output by the memory when the memory completes a given read operation and the second clock signal. The memory access time is determined based on the first and second phase skews.