Migrating operating system instances across distinct physical hosts is a useful tool for administrators of data centers and clusters: It allows clean separation between hard-ware software, facilitates fault management, load balancing, low-level maintenance.By carrying out the majority migration while OSes continue to run, we achieve impressive performance with minimal service downtimes; demonstrate entire OS on commodity cluster, recording downtimes as low 60ms. We show that our sufficient...

SUMMARY Hummingbirds are specialized for hovering flight, and substantial research has explored this behavior. Forward flight is also important to hummingbirds,but the manner in which they perform forward not well documented. Previous suggests that hummingbirds increase velocity by simultaneously tilting their body angle stroke-plane of wings,without varying wingbeat frequency upstroke: downstroke span ratio. We hypothesized other wing kinematics besides would vary hummingbirds. To test...

Many software attacks are based on injecting malicious code into a target host. This paper demonstrates the use of well-known technique, data tainting, to track received from network as it propagates through system and prevent its execution. Unlike past approaches taint tracking, which tainted by running completely in an emulator or simulator, resulting considerable execution overhead, our work ability dynamically switch between virtualized emulated Using this we able explore hardware...

This paper presents a new time-domain measurement technique for repetitive microwave signals that is applied to modeling wideband power amplifiers. The concept consists of recording the signal after conversion baseband using calibrated downconverter, which improves accuracy compared measurements at carrier frequency. section describes how such can be used model effects in nonlinear commonly memory-less envelope limited use on narrowband signals. A developed includes filter before...

Coevolution of male and female genitalia in waterfowl has been hypothesized to occur through sexual conflict. This hypothesis raises questions about the functional morphology penis mechanics copulation waterfowl, which are poorly understood. We used high-speed video phallus eversion histology describe for first time avian penis. Eversion 20 cm muscovy duck is explosive, taking an average 0.36 s, achieving a maximum velocity 1.6 m s −1 . The collagen matrix very thin not arranged...

Behavioural displays are a common feature of animal courtship. Just as female preferences can generate exaggerated male ornaments, for dynamic behaviours may cause males to perform courtship near intrinsic performance limits. I provide an example extreme display, the dive Anna's hummingbird ( Calypte anna ). Diving hummingbirds were filmed with combination high-speed and conventional video cameras. After powering initial stage by flapping, folded their wings sides, at which point they...

During courtship flights, males of some hummingbird species produce diverse sounds with tail feathers varying shapes. We show that these are produced by air flowing past a feather, causing it to aeroelastically flutter and generate flutter-induced sound. Scanning laser doppler vibrometery high-speed video individual different sizes shapes in wind tunnel revealed multiple vibratory modes range acoustic frequencies harmonic structures. Neighboring can be aerodynamically coupled either at the...

The elongated tails adorning many male birds have traditionally been thought to degrade flight performance by increasing body drag. However, aerodynamic interactions between the and tail can be substantial in some contexts, a short may actually reduce rather than increase overall To test how length affects performance, we manipulated of Anna's hummingbirds (Calypte anna) their with greatly streamers red-billed streamertail (Trochilus polytmus) reducing removing first rectrices then entire...

A diverse array of birds apparently make mechanical sounds (called sonations) with their feathers. Few studies have established that these are non-vocal, and the mechanics how produced remains poorly studied. The loud, high-frequency chirp emitted by a male Anna's hummingbird ( Calypte anna ) during his display dive is debated example. Production sound was originally attributed to tail, but more recent study argued vocal. Here, we use high-speed video diving birds, experimental manipulations...

Phenotypic characters with a complex physical basis may have correspondingly evolutionary history. Males in the "bee" hummingbird clade court females sound from tail-feathers, which flutter during display dives. On phylogeny of 35 species, frequency evolves as gradual, continuous character on most branches. But at least six internal branches fall two types major, saltational changes: mode changes, or feather that is source causing to jump one discrete value another. In addition their tail...

Abstract Wingbeat frequency estimation is an important aspect for the study of avian flight, energetics, and behavioral patterns, among others. Hummingbirds, in particular, are ideal subjects to test a method this due their fast wing motions unique aerodynamics, which results from ecological diversification, adaptation high-altitude environments, sexually selected displays. Traditionally, wingbeat measurements have been done via “manual” image/sound processing. In study, we present automated...

Aerodynamic theory predicts that the mechanical costs of flight are lowest at intermediate speeds; metabolic should trend similarly if muscle efficiency is constant. We measured rates for nine Anna's hummingbirds (Calypte anna) and two male Allen's (Selasphorus sasin) feeding during from a free-standing mask over range airspeeds. Ten 11 birds exhibited higher hovering than airspeeds, whereas one individual comparable forward up to speeds approximately 7 m s(-1). Flight all increased Relative...

The sedentary subspecies of Allen's Hummingbird (Selasphorus sasin sedentarius) was originally endemic to the Channel Islands off coast Southern California, but it colonized mainland at Palos Verdes Peninsula sometime before 1966. In decades since, its population has expanded in California. I tracked growth using eBird checklists. range S. s. sedentarius grown from ∼70 km2 1970 ∼13,000 today, representing an increase ≤23% total species as a whole. Its main habitat within Los Angeles, Orange,...

Tonal, nonvocal sounds are widespread in both ordinary bird flight and communication displays. We hypothesized these attributable to an aerodynamic mechanism intrinsic feathers: aeroelastic flutter. Individual wing tail feathers from 35 taxa (from 13 families) that produce tonal were tested a wind tunnel. In the tunnel all of could flutter generate sound, suggesting capacity is feathers. This result implies potentially birds. However, produced replicated actual only 15 taxa. Of 20 negative...

An accurate nonlinear model is necessary to optimize the tradeoff between efficiency and linearity in power amplifiers. Gain compression (AM/AM) amplitude-phase (AM/PM) distortion are two primary inputs used characterize nonlinearity. The amplifier's AM/AM AM/PM characteristics typically measured statically using a vector network analyzer. Since input modulated signal, it desirable amplifier dynamically. This paper describes demonstrates dynamic measurement modeling technique involving...

Courtship displays frequently include complex signals that females use to pick a mate. Male Costa's hummingbirds (Calypte costae) generate two acoustic during courtship: vocal song produced close female and dive-sound courtship dive. The sound similar, both were assumed be vocally by the syrinx. Here, we show they are not; whereas is syrinx, high-frequency fluttering of outermost tail feathers. Anna's hummingbird anna), sister Costa's, also sings produces with wings feathers sounds similar...

Abstract Multi-component signals contain multiple signal parts expressed in the same physical modality. One way to identify individual components is if they are produced by different mechanisms. Here, I studied mechanisms generating acoustic courtship displays of Calliope hummingbird Stellula calliope. Display dives consisted three synchronized sound elements, a high-frequency tone (hft), low frequency (lft), and atonal pulses (asp), which were then followed frequency-modulated fall....

Males in the 'bee' hummingbird clade produce distinctive, species-specific sounds with fluttering tail feathers during courtship displays. Flutter may be result of vortex shedding or aeroelastic interactions. We investigated underlying mechanics flutter and sound production a series different wind tunnel. All tested were capable at frequencies varying from 0.3 to 10 kHz. At low airspeeds (Uair) feather was highly damped, but threshold airspeed (U*) abruptly entered limit-cycle vibration...

This paper presents a method of assessing the fidelity nonlinear amplifier models for communications applications. The simulation predictions BPSK and 16-QAM input signals are compared to measurements 20 GHz solid-state amplifier. It is shown that including filter before memoryless nonlinearity provides significantly improved model alone.

Studies on the sonations (nonvocal communicative sounds) of birds have revealed a wide diversity mechanisms and functions. We describe kinematics sounds display dive shuttle male Black-chinned Hummingbird (Archilochus alexandri). Males produced an integrated series trilled tonal during their displays. Through combination experiments wild birds, isolated feathers in laboratory, comparisons between high-speed video audio recordings, we show that are by feathers. The timing both displays...