Closed Canopies Crowd Out Bats: Planning Artificial Gap Creation

Managed even-aged forest stands often lack small to medium-sized canopy gaps that help to increase habitat diversity and, in turn, wildlife diversity. A large body of literature suggests that this habitat diversity is especially important for bat communities and that bat activity and diversity can be depressed in closed canopy, even-aged stands. Open- and edge-adapted bats have evolved specific wing morphologies and echolocation call structures that make them reliant upon forest gaps as energy efficient foraging grounds in otherwise structurally cluttered forests. Artificial gap creation projects that increase habitat diversity have been implemented to benefit ungulates, and a similar approach could also be applied to support foraging activity of bats in even-aged forests that lack dynamic natural disturbances. However, little consideration has been given to the use of gaps by bats and no comprehensive approach for artificial gap creation for the benefit of bats has been proposed. In response to this lack of guidance for forest managers in the Pacific Northwest region, this document provides a focused review of existing literature regarding bats and gaps. This information was used to create specific management recommendations regarding physical characteristics of gaps and their spatial context on the landscape. To identify ideal locations for gap creation on the ground according to these recommendations, a weighted overlay method is suggested. This document has been written for the use of forest managers throughout the entire Pacific Northwest region. However, the Siuslaw National Forest (NF), a Late-Successional Reserve on the coast of Oregon, was used as a specific case study to demonstrate how the proposed approach can be applied to a specific management unit. The document is broken into the four following chapters. Chapter 1 introduces the Siuslaw NF and briefly describes the forest’s bat community, major vegetation zones, forest succession, disturbance regime, and management. Using previous research from the region as a guide, Chapter 2 provides background information regarding bat biology and ecology and it details the importance of gaps, forest edges, and interior stands as habitat for forest-dwelling bats. Different types of forest gaps common to the Pacific Northwest are discussed including both artificially created and naturally occurring gaps. Chapter 3, again guided by review of existing literature, highlights important gap parameters including physical characteristics and spatial context to promote bat activity as well as provides specific gap management recommendations. Chapter 4 provides an example of how to input management recommendations into a Geographic Information System (GIS) to pinpoint ideal locations for gap creation within a management unit. A weighted overlay analysis, a common GIS tool, was conducted in the Siuslaw NF following the management guidelines, and resulting maps are discussed. The ultimate goal of this document is to provide forest managers in the Pacific Northwest region with the knowledge and planning tools necessary to promote foraging activity of specialized open- and edge-adapted species. While other management units may have different or additional managerial constraints than those of the Siuslaw NF, thIS proposed approach can be easily adapted to meet the varied needs of different forests. By following this approach, forest managers can provide the habitat diversity and complexity necessary to promote high levels of bat activity and diversity within even-aged, closed canopy forests.

The mechanism of gap creation by a multifunctional nuclease during base excision repair

During base excision repair, a transient single-stranded DNA (ssDNA) gap is produced at the apurinic/apyrimidinic (AP) site. Exonuclease III, capable of performing both AP endonuclease and exonuclease activity, are responsible for gap creation in bacteria. We used single-molecule fluorescence resonance energy transfer to examine the mechanism of gap creation. We found an AP site anchor-based mechanism by which the intrinsically distributive enzyme binds strongly to the AP site and becomes a processive enzyme, rapidly creating a gap and an associated transient ssDNA loop. The gap size is determined by the rigidity of the ssDNA loop and the duplex stability of the DNA and is limited to a few nucleotides to maintain genomic stability. When the 3′ end is released from the AP endonuclease, polymerase I quickly initiates DNA synthesis and fills the gap. Our work provides previously unidentified insights into how a signal of DNA damage changes the enzymatic functions.

Reconfigurable magnonic mode-hybridisation and spectral control in a bicomponent artificial spin ice

Strongly-interacting nanomagnetic arrays are finding increasing use as model host systems for reconfigurable magnonics. The strong inter-element coupling allows for stark spectral differences across a broad microstate space due to shifts in the dipolar field landscape. While these systems have yielded impressive initial results, developing rapid, scaleable means to access a broad range of spectrally-distinct microstates is an open research problem. We present a scheme whereby square artificial spin ice is modified by widening a ‘staircase’ subset of bars relative to the rest of the array, allowing preparation of any ordered vertex state via simple global-field protocols. Available microstates range from the system ground-state to high-energy ‘monopole’ states, with rich and distinct microstate-specific magnon spectra observed. Microstate-dependent mode-hybridisation and anticrossings are observed at both remanence and in-field with dynamic coupling strength tunable via microstate-selection. Experimental coupling strengths are found up to g/2π = 0.16 GHz. Microstate control allows fine mode-frequency shifting, gap creation and closing, and active mode number selection.

Space-Time Cloaking Based on Reflection, Transmission and Goos-Hãnchen Shift

The birefringence characteristics of reflection and transmission of light pulse are explored in chiral medium driving by two probe electric and magnetic fields, while four control fields. The proposed medium show significant birefringence behaviors in reflection/transmission and Goos-Hänchen (GH) shifted beams. The birefringent GH-reflected and GH-transmitted pulses show significant contribution in the space time gap creation for secure communication and invisibility. A space-time gap has been observed in the reflection, transmission and corresponding GH-shifted reflection and transmission birefringent beams. The theoretical results may be useful for noise free secure communication in invisible radar technology.

Reconfigurable magnonic mode-hybridisation and spectral control in a bicomponent artificial spin ice

Strongly-interacting nanomagnetic arrays are finding increasing use as model host systems for reconfigurable magnonics. The strong inter-element coupling allows for stark spectral differences across a broad microstate space due to shifts in the dipolar field landscape. While these systems have yielded impressive initial results, developing rapid, scaleable means to access abroad range of spectrally-distinct microstates is an open research problem.We present a scheme whereby square artificial spin ice is modified by widening a ‘staircase’ subset of bars relative to the rest of the array, allowing preparation of any ordered vertex state via simple global-field protocols. Available microstates range from the system ground-state to high-energy ‘monopole’ states, with rich and distinct microstate-specific magnon spectra observed. Microstate-dependent mode-hybridisation and anticrossings are observed at both remanence and in-field with dynamic coupling strength tunable via microstate-selection. Experimental coupling strengths are found up to g/2π = 0.15 GHz. Microstate control allows fine mode-frequency shifting, gap creation and closing, and active mode number selection

Defining and Analyzing Forceful Gap Behavior at Unsignalized Intersections

Under mixed-mode traffic conditions prevailing on Indian roads at unsignalized intersections, it is commonly observed that vehicles entering from minor streets indulge in forceful gap creation/delay for the vehicles moving on the major road. Although this driving behavior has been reported in some of the published studies for Indian traffic conditions, a clear definition of such forceful entries is not available. An attempt has been made in this study to define this forceful entry phenomenon on the basis of changes in the speed of major streets’ vehicles approaching the intersection on a typical case of mixed-traffic environs. In this regard, field observations were recorded through videography to obtain the speed reduction threshold value for categorizing an entry as a forceful entry. To quantify the above, data in relation to various vehicle types approaching intersections and their associated speeds at the reference area were extracted at the approach arms of the intersection. On the basis of observations, collected data were divided into three scenarios: ( 1 ) vehicles on major roads reduce their speed when vehicles are absent on minor roads; ( 2 ) vehicles on major roads reduce their speed when vehicles are waiting on minor roads; and ( 3 ) vehicles on major roads reduce their speed when vehicles from minor roads have accepted the gap/lag for movement. The changes in speed in all the three scenarios were compared to identify forceful entries with the base case of normal traffic flow on the major road without the existence of forceful entry phenomenon. The study revealed that the speed reduction to the extent of 73% is considered as a forceful entry at the selected location. Furthermore, the study estimated the effect of forceful behavior on critical gap at unsignalized intersections.