Cavity Density Research Articles

Density and characteristics of tree cavities inside and outside Volcanoes National Park, Rwanda.

Tree cavities, formed by animal excavation or processes of fungal decay and mechanical damage, may provide nesting, roosting, or resting opportunities to many invertebrate and vertebrate species. Although cavity availability has been linked to patterns of biodiversity and ecosystem functioning elsewhere, there have been few such studies in the Afrotropics. Here, we present a baseline survey of cavity availability inside the high elevation (2200–3714 m) Afromontane forest ecosystems of Volcanoes National Park (VNP), Rwanda. We aimed to provide such reference data in the form of summary statistics on cavity density and characteristics in a collection of 400 m2 plots that together cover 8.8 ha inside and 0.68 ha outside VNP. We also explored the relative importance of fungal decay vs. excavators in the formation of cavities, tested for the relative role of standing dead trees and living trees as cavity substrates, considered differences in diameter and height between cavity‐bearing trees and trees without cavities, tested whether cavity density varies across elevation, and determined the orientation of cavity entrances. We found 109 cavities in 52 cavity‐bearing trees (dominated by Hagenia abyssinica) inside VNP, for a density of 12.4 cavities and 5.9 cavity‐bearing trees per hectare, and none outside the park. More cavities were decay‐formed (n = 90) than excavated (n = 19), and though most cavities were found in living trees (n = 44), the number of cavities in dead trees (n = 8) was high relative to dead tree substrate availability. We also found that cavity‐bearing trees were larger than those without cavities, that excavated cavities were predominantly oriented toward the southeast and decay‐formed cavities to the northeast, and that cavity density declined with increases in elevation. Our results show that large and dead trees of particular species are important cavity substrates that need to be given attention in conservation and management, as is clearly illustrated by the lack of cavities in the highly managed Eucalyptus stands outside VNP.

Dynamics of homogeneous cavitation with pressure feedback

Theoretical studies of homogeneous cavitation have largely been based on the classical nucleation theory. However, existing cavitation models cannot adequately describe its dynamics at nanosecond timescale, which has been called for in other fields. We develop a model coupling nucleation kinetics with cavity growth and pressure feedback as saturation mechanisms. Our numerical studies reveal the exponential dependence of cavitation characteristics such as saturation cavity density and most probable cavity radius on model parameters: Tolman length and initial pressure. This work also sheds light on the possibility of accurately determining Tolman length, whose value has a large spread in the literature.

Plasmon-assisted low-threshold nanolasers

Low power consumption is of great importance for on-chip optical applications of nanolasers. To reduce the lasing threshold, a high quality factor and strong Purcell effect are vital, while the latter is often hindered by the above-diffraction-limit mode volume of photonic cavity, and its improvement generally requires complicated cavity design. We show that by coupling to an off-resonant plasmonic antenna, the lasing threshold of a photonic cavity can be reduced over a wide range of parameters where the plasmon-assisted coherent light-matter interaction dominates over the plasmon-induced dissipation. We develop a semiclassical model of a two-level nanolaser for such a hybrid plasmonic-photonic cavity, which is consistent with the quantum description of the spectral density of a hybrid cavity. The analytical expression of the lasing threshold is derived, which can be utilized to optimize the system parameters associated with cavities designed to obtain the minimum lasing threshold. Through comprehensive study, we find that compared to all-dielectric photonic cavity, a hybrid cavity can have prominent advantages in lasing with lower threshold, narrower emission linewidth, and sustaining the higher-power output of laser field. Our paper demonstrates the possibility of utilizing a hybrid plasmonic-photonic cavity to fabricate room-temperature low-threshold nanolasers.

Cavitation behavior during tensile deformation at room temperature in fine-grained pure magnesium

Cavitation behavior associated with grain boundary sliding at room temperature was investigated using fine-grained magnesium (Mg) specimens produced by extrusion or high-pressure torsion. Regardless of the process method, flow stress in both of Mg specimens depended on the tensile strain rate, and the strain rate sensitivities (m-values) were determined to be approximately 0.3 at low strain rates. Deformed microstructural observations revealed that many cavities were formed at grain boundaries and grain boundary triple junctions, even during the plastic deformation at room temperature. The size and density of such cavities increased with the progression of deformation. The majority of cavities were controlled by plasticity, and the cavity growth rate was similar to those typically observed in superplastic Mg alloys subjected to elevated temperature tensile tests. In addition, initial basal texture was unlikely to affect these cavitation behaviors, e.g., cavity growth rate.

Efficacy of Fenestration Decompression for the Treatment of Oral and Maxillofacial Cysts.

Background Surgery is the mainstay of treatment for oral and maxillofacial cysts. Compared with open surgery that will bring more harm to patients, fenestration decompression, as a surgical method with good curative effects and little damage, has received increasing attention in the treatment of oral and maxillofacial cysts. Methods The clinical data of 135 patients with oral and maxillofacial cysts visited the Fifth Central Hospital of Tianjin between June 2019 and September 2021 were collected for retrospective analysis. Patients were assigned to two groups based on the treatment plan implemented: the control group (n = 64) treated with curettage of cysts and the observation group (n = 71) with fenestration decompression. Therapeutic efficacy parameters and surgical indicators were detected. Additionally, postoperative cyst, pain, complication rate, and recurrence, as well as life quality six months after treatment, were evaluated and compared. Results In comparison with the control group, the observation group was observed to have a higher total effective rate, less operation time, shorter hospital stays, and less intraoperative bleeding (P < 0.05). In addition, the shrinkage rate, shrinkage volume, and postoperative density of the cyst cavity were higher in the observation group than in the control group (P < 0.05). The observation group also outperformed the control group with lower postoperative VAS score, complication rate, and half-year recurrence rate (P < 0.05). Furthermore, significantly better life quality was determined in the observation group after half a year of treatment (P < 0.05). Conclusion Fenestration decompression is highly effective in treating oral and maxillofacial cysts, contributing to fewer complications, markedly relieved symptoms, shorter hospitalization time, well-preserved facial nerves, and low recurrence rate in the later period, which is worthy of clinical promotion.

Diagnostics and methods of solving the reduction of bone mineral density and deformities of the articular cavity of the scapula during reverse shoulder arthroplasty

Background. Reverse arthroplasty is an effective method of treating severe injuries and diseases of the shoulder joint. In cases of severe osteoporosis, defects and deformities of the glenoid, there are risks of incorrect installation and instability of the components of the endoprosthesis. In the literature data, the problem of osteoporosis in the endoprosthetics of the shoulder joint and methods of its solution are rather poorly reflected, which was the reason for this study.The aim: to develop algorithms for diagnosing the state of the bone tissue of the articular cavity of the scapula and methods for solving its deviations during reverse shoulder arthroplasty.Materials and methods. Forty-eight patients who underwent reversible shoulder joint replacement were examined in the Department of Adult Orthopedics of the N.N. Priorov National Medical Research Center of Traumatology and Orthopedics. A standard preoperative examination of patients developed in the department was performed, as well as additional calculations of bone density in Hounsfield units and according to X-ray densitometry were performed. The parameters of bone density of the glenoid (in HU) were compared with the data of densitometry.Results. According to the results of densitometry, the patients were divided into groups. A direct dependence of the bone density of the glenoid and the indicators of densitometry was revealed. Algorithms of treatment and preoperative preparation of patients with bone density deficiency for reverse shoulder arthroplasty have been developed.Conclusions. In the studied groups, 100 % of patients with indicators below 139 HU were diagnosed with osteoporosis or osteopenia, and patients with more than 257 HU had normal bone mineral density.

Nonlinear interaction effects in a three-mode cavity optomechanical system

We investigate the resonant enhancement of nonlinear interactions in a three-mode cavity optomechanical system with two mechanical oscillators. Using the Keldysh Green's function technique, we find that nonlinear effects on the cavity density of states can be greatly enhanced by the resonant interaction of two phononic polaritons, due to their small effective dissipation. In the large detuning limit and taking into account an upper bound on the achievable dressed coupling, the optimal point for probing the nonlinear effect is obtained, showing that such a three-mode system can exhibit significant nonlinear features also for relatively small values of $g/\ensuremath{\kappa}$.

Unusual dynamical properties of disordered polaritons in microcavities

The strong light-matter interaction in microcavities gives rise to intriguing phenomena, such as cavity-mediated transport that can potentially overcome the Anderson localization. Yet, an accurate theoretical treatment is challenging as the matter (e.g.,molecules) are subject to large energetic disorder. In this article, we develop the Green's function solution to the Fano-Anderson model and use the exact analytical solution to quantify the effects of energetic disorder on the spectral and transport properties in microcavities. Starting from microscopic equation of motions, we derive an effective non-Hermitian Hamiltonian and predict a set of scaling laws: (i) The complex eigen-energies of the effective Hamiltonian exhibit an exceptional point, which leads to underdamped coherent dynamics in the weak disorder regime, where the decay rate increases with disorder, and overdamped incoherent dynamics in the strong disorder regime, where the slow decay rate decreases with disorder. (ii) The total density of states of disordered ensembles can be exactly partitioned into the cavity, bright-state and dark-state local density of states, which are determined by the complex eigen solutions and can be measured via spectroscopy. (iii) The cavity-mediated relaxation and transport dynamics are intimately related such that the energy-resolved relaxation and transport rates are proportional to the cavity local density of states. The ratio of the disorder averaged relaxation and transport rates equals the molecule number, which can be interpreted as a result of a quantum random walk. (iv) A turnover in the rates as a function of disorder or molecule density can be explained in terms of the overlap of the disorder distribution function and the cavity local density of states. These findings reveal the significant impact of the dark states on the transport properties of disordered ensembles in cavities.

Understanding the stress corrosion cracking growth mechanism of a cold worked alumina-forming austenitic steel in supercritical carbon dioxide

The crack growth behavior of a cold worked alumina-forming austenitic (AFA) steel in supercritical carbon dioxide (sCO2) and Ar is studied. AFA steel exhibits higher crack growth rates in sCO2 than in Ar in the temperature range of 550 °C~650 °C. Creep cavities are widely observed near the crack growth paths and ahead of the crack tips on the specimens tested in both environments. Higher cavity density is observed at the crack tip of the specimen tested in sCO2, which is caused by oxidation and carburization. The high cavity density weakens the grain boundaries and accelerates the fracture of the materials.

Electron acceleration from the interaction of three crossed parallel Alfvén waves

We study the nonlinear interaction of three parallel Alfvén wave packets (AWPs) in an initially uniform plasma using 2.5-dimensional particle-in-cell (PIC) numerical simulations. We aim to help to explain the observation of suprathermal electrons by the collision of multiple Alfvén waves in regions where these waves are trapped like the IAR (Ionospheric Alfvén Resonator), Earth radiation belts or coronal magnetic loops. In the context of the acceleration by the parallel Alfvén waves interactions (APAWI) process that has been described by Mottez (Ann. Geophys., vol. 30, issue 1, 2012, pp. 81–95; J. Plasma Phys., vol. 81, issue 1, 2015, p. 325810104), the interaction of two parallel Alfvén waves (AWs) generates longitudinal density modulations and parallel electric fields at the APAWI crossing region that can accelerate particles effectively in the direction of the background magnetic field. Our simulations show that when a third parallel AWP of different initial position arrives at the APAWI crossing region, it gives rise to a strong parallel electron beam ( $V \sim 5\text {--}7 V_{Te}$ ) at longitudinal cavity density gradients. We suggest that velocity drift from an outgoing AW generates interface waves in the transverse direction, which allows propagating waves to develop parallel electric fields by the phase mixing process when $k_{\perp }^{-1}$ of the wavy density gradient (oblique gradient) is in the range of the electron inertial length $c/\omega _{p0}$ .

Monte Carlo investigation of electron fluence perturbation in MRI-guided radiotherapy beams using six commercial radiation detectors

With the integration of treatments with MRI-linacs to the clinical workflow, the understanding and characterization of detector response in reference dosimetry in magnetic fields are required. The external magnetic field perturbs the electron fluence. The degree of perturbation depends on the irradiation conditions and on the detector type. The purpose of this study is to evaluate the magnetic field impact on the electron fluence spectra in several detectors to provide a deeper understanding of detector response in these conditions. Monte Carlo calculations of the electron fluence are performed in six detectors (solid-state: PTW60012 and PTW60019, ionization chambers: PTW30013, PTW31010, PTW31021, and PTW31022) in water and irradiated by a 7 MV FFF photon beam with a small and a reference field, at 0 and 1.5 T. Three chamber axis orientations are investigated: parallel or perpendicular (either the Lorentz force pointing towards the stem or the tip) to the magnetic field and always perpendicular to the photon beam. One orientation for the solid-state detector is studied: parallel to the photon beam and perpendicular to the magnetic field. Additionally, electron fluence spectra are calculated in modified detector geometries to identify the underlying physical mechanisms behind the fluence perturbations. The total electron fluence in the Farmer chamber varies up to 1.24% and 5.12% at 1.5 T, in the parallel and perpendicular orientation, respectively. The interplay between the gyration radius and the Farmer chamber cavity length significantly affects the electron fluence in the perpendicular orientation. For the small-cavity chambers, the maximal variation in total electron fluence is 0.19% in the parallel orientation for the reference field. Significant small-field effects occur in these chambers; the magnetic field reduces the total electron fluence (with respect to the no field case) between 9.86% and 14.50%, depending on the orientation. The magnetic field strongly impacted the solid-state detectors in both field sizes, probably due to the high-Z components and cavity density. The maximal reductions of total electron fluence are 15.06 ± 0.09% (silicon) and 16.00 ± 0.07% (microDiamond). This work provides insights into detector response in magnetic fields by illustrating the interplay between several factors causing dosimetric perturbation effects: (1) chamber and magnetic field orientation, (2) cavity size and shape, (3) extracameral components, (4) air gaps and their asymmetry, (5) electron energy. Low-energy electron trajectories are more susceptible to change in magnetic fields, and are associated with detector response perturbation. Detectors with higher density and high-Z extracameral components exhibit more significant perturbations in the presence of a magnetic field, regardless of field size.

Effect of forest logging on food availability, suitable nesting habitat, nest density and spatial pattern of a Neotropical parrot

Secondary cavity nesters, bird species that rely on the presence of existing cavities, are highly vulnerable to anthropogenic and stochastic processes that reduce the availability of cavity bearing trees. The most common logging practice in Neotropical forests is selective logging, where a few valuable tree species are logged, primarily old, large trees that are the most prone to develop cavities and produce larger amounts of fruits and seeds. Tucuman Amazon, Amazona tucumana, is a threatened parrot that relies on the tree-cavities and food provided by large, old trees. Our objective was to evaluate how logging affects 1) stand and nest plot forest structure, 2) nesting site selection, 3) food availability, 4) density of suitable cavities, 5) nest density, and 6) nest spatial pattern of Tucuman Amazon by comparing a mature undisturbed forest in a National Park (NP) vs a logged forest (LF). We determined the availability of suitable cavities and food resources consumed by Tucuman Amazon, and we compared nest density and spatial pattern of nests between NP vs LF. The Index of food availability for all tree species consumed by Tucuman Amazon and for P. parlatorei were significantly higher in NP than in LF (34.5 ± 13.3 m ha−1 vs. 3.5 ± 1.0 m ha−1 and 5.6 ± 2.3 m ha−1 vs. 1.2 ± 1.0 m ha−1, respectively). Density of suitable cavities for nesting in the NP was significantly higher than in the LF: 4.6 cavities ha−1 [C.I. 95 %: 3.07 – 7.04 cavities ha−1] vs. 1.1 cavities ha−1 [C.I. 95 %: 0.73 – 1.66 cavities ha−1], respectively. Mean density of Tucuman Amazon nests was significantly higher in the NP than in LF (0.25 ± 0.04 vs. 0.06 ± 0.04 nest ha−1, respectively). Food availability is an important factor that affects Tucuman Amazon populations and when food is not limiting, the availability of suitable cavities and territorial behavior could play a role in regulating nest density. When evaluating the limiting factors for secondary cavity-nesting species of conservation concern it is important to evaluate the interplay of a set of potential limiting factors to propose sound forest management recommendations.

Modeling of cavity nucleation, early‐stage growth, and sintering in polycrystal under creep–fatigue interaction

AbstractA mechanistic‐based cavitation model that considers nucleation, early‐stage growth, and sintering under creep–fatigue interaction is proposed to predict the number density of cavities ρ. Both the nucleation and early‐stage growth rates, controlled by grain boundary (GB) sliding under tension, are formulized as a function of local normal stress σn. Cavity sintering that occurs during the compression is governed by the unconstrained GB diffusion depending on the σn. Modeling results provide important insights into experimental load‐waveform design. First, test with initial compression promotes higher ρ compared to the initial tension, if the unbalanced hold time in favor of tension is satisfied. Second, the ρ value does not have a monotonic dependence on either the compressive hold time or stress, because of their competing effect on nucleation and sintering. Third, the optimum value of stress variation rate exists in terms of obtaining the highest ρ value due to sintering effect.

Large-scale and high-quality III-nitride membranes through microcavity-assisted crack propagation by engineering tensile-stressed Ni layers

Epitaxially grown III-nitride alloys are tightly bonded materials with mixed covalent-ionic bonds. This tight bonding presents tremendous challenges in developing III-nitride membranes, even though semiconductor membranes can provide numerous advantages by removing thick, inflexible, and costly substrates. Herein, cavities with various sizes were introduced by overgrowing target layers, such as undoped GaN and green LEDs, on nanoporous templates prepared by electrochemical etching of n-type GaN. The large primary interfacial toughness was effectively reduced according to the design of the cavity density, and the overgrown target layers were then conveniently exfoliated by engineering tensile-stressed Ni layers. The resulting III-nitride membranes maintained high crystal quality even after exfoliation due to the use of GaN-based nanoporous templates with the same lattice constant. The microcavity-assisted crack propagation process developed for the current III-nitride membranes forms a universal process for developing various kinds of large-scale and high-quality semiconductor membranes.

Estimation of Postcardiac Arrest Interval Based on Atrial Cavity Density in Postmortem Computed Tomography.

Intracardiac hypostasis is frequently observed in postmortem computed tomography (PMCT) of acute deaths, and it becomes clearer as the postmortem interval increases. To determine the postcardiac arrest interval (PCAI), we evaluated densities of the right and left atria [anterior part of the right atrium (AR) and posterior part of the left atrium (PL)] using postmortem computed tomographic images. A total of 184 patients were included in the study. Patients with return of spontaneous circulation and those with final alive confirmation time over 1 hour were excluded. We evaluated the density of AR and PL at the level of the right inferior pulmonary vein entry to the left atrium. We defined the interval between the estimated cardiac arrest time and the postmortem CT time as the PCAI. There was a negative correlation between AR and PCAI in 59 patients who died owing to cardiovascular disease. The regression equation (PCAI = -1.725 × AR + 132.95) was obtained based on this result. There was no correlation between PL and PCAI. The result suggests that the density of the anterior part of the right atrium decreases as postcardiac arrest interval increases in the case of cardiovascular disease. The regression equation may be used as an additional method to estimate postcardiac arrest interval.

A quantitative gain‐independent assessment of the left atrial appendage as a method of thromboembolic risk stratification

Visual assessment of the left atrial appendage (LAA) by echocardiography for the presence of thrombus is inherently qualitative. However, whether quantitative assessments can provide increased value over qualitative assessment has not been thoroughly examined. One hundred and thirty-eight patients (mean age 59 ± 13 years, 70% male) undergoing transesophageal echocardiography prior to pulmonary vein isolation or electrical cardioversion were retrospectively studied. LAA were examined by two expert readers and identified as thrombus, sludge, spontaneous echocardiograph contrast, or normal. LAA were then separately examined to calculate a gain-independent ratio between the average pixel density of the LAA cavity and that of the LAA wall (C/W ratio). C/W ratio was significantly related with qualitative LAA analysis (p < 0.0001) and with thromboembolic events (OR 1.60, 95% CI 1.095-2.347, p=0.02). The C/W ratio (AUC 0.73, 95% CI 0.60-0.86) was a reliable predictor for future thromboembolic events when compared to expert reader LAA assessment (Expert Reader 1 AUC=0.72, 95% CI 0.53-0.90; Expert Reader 2 AUC=0.69). The C/W ratio may be a complementary method to adjudicate thromboembolic risk in patients with AF that is readily quantifiable at time of TEE.

Study on the SCC behavior induced by creep cavities on scratched surface of Alloy 690TT in high temperature water

SCC behavior induced by creep of Alloy 690TT in high temperature water was investigated in this study using scanning electron microscopy (SEM) with energy dispersive X-ray (EDS) detector and electron back-scattered diffraction (EBSD) detector. The results showed that the creep cavities could be formed in the stress concentration zones on the interface between the intergranular carbides and matrix. The distribution density of creep cavities was related to the strain level. The cavities mainly distributed on the grain boundaries close to the applied load direction in the high strain zones underneath the scratches. The creep cavities tended to form near the intergranular carbides distributed in a semi-continuous line along the grain boundaries, which was beneficial to the SCC propagation. On the contrary, the local cellular carbides might not be conducive to the formation of creep cavities and inhibited the growth of SCC cracks. In the high strain zone underneath the scratch, the SCC cracks mainly propagated along or close to the direction of applied load.

Dolmens, sepulchral caves and hypogea in Provence

This contribution concerns the regional administrative entity of Provence-Alpes-Côte d'Azur and the south of Drôme. A cartographic analysis looking for possible territorial and geographical specificities allowed us to identify some trends: the distribution of cave burials is not proportional to the density of natural cavities; the distribution zones of dolmens and caves are not exclusive; hypogees, strongly dependent on suitable rocks for their excavation, were chosen as burials in a very limited sector. On the other hand, as the documentation is very unequal for the 262 collective burials selected, the comparison of funerary practices according to architectural type unfortunately remains an open question.

Helium causing disappearance of a/2&lt;111&gt; dislocation loops in binary Fe-Cr ferritic alloys

Single and dual-beam self-ion irradiations were performed at 500°C on ultra-high purity Fe14%Cr alloy to ∼0.33 displacements-per-atom (dpa), and 0 or 3030 atomic-parts-per-million (appm) helium/dpa, respectively. Using transmission electron microscopy, we reveal that helium can drastically modify the dislocation loop Burgers vector in Fe-Cr alloys. Helium co-implantation caused complete disappearance of a/2<111> type dislocation loops, and the microstructure consisted of only a<100> loops. Conversely, a/2<111> type loops were predominant without He co-implantation. The total loop density remained largely unaffected. The results strikingly contrast literature asserting that helium stabilizes a/2<111> type loops in bcc Fe alloys, based on low temperature irradiations. Collectively analyzing the results with literature suggest that the small positive interaction between helium and self-interstitial atoms (SIA) in Fe predicted by atomistic simulations maybe insufficient to holistically explain the dislocation loop microstructure development in presence of helium. Helium-SIA positive binding inadvertently implies elevated a/2<111> loop fraction and higher loop densities that the present results contradict. Helium induced high cavity density causing a preferential loss of highly glissile <111> clusters, leaving the matrix saturated with <100> type clusters is proposed as a potential mechanism. Further, the in-situ irradiations combined with Burgers vector analysis strengthened the evidence of Cr-induced dislocation loop mobility reduction that appears to stabilize the a/2<111> type loops and causes higher loop densities in Fe-Cr alloys.

Roosting ecology of endangered plant-roosting bats on Okinawa Island: Implications for bat-friendly forestry practices.

Roosting information is crucial to guiding bat conservation and bat‐friendly forestry practices. The Ryukyu tube‐nosed bat Murina ryukyuana (Endangered) and Yanbaru whiskered bat Myotis yanbarensis (Critically Endangered) are forest‐dwelling bats endemic to the central Ryukyu Archipelago, Japan. Despite their threatened status, little is known about the roosting ecology of these species and the characteristics of natural maternity roosts are unknown. To inform sustainable forestry practices and conservation management, we radio‐tracked day roosts of both species in the subtropical forests of Okinawa's Kunigami Village District. We compared roost and roost site characteristics statistically between M. ryukyuana nonmaternity roosts (males or nonreproductive females), maternity roosts, and all M. yanbarensis roosts. Generalized linear models were used to investigate roost site selection by M. ryukyuana irrespective of sex and age class. Lastly, we compiled data on phenology from this and prior studies. Nonreproductive M. ryukyuana roosted alone and primarily in understory foliage. Murina ryukyuana maternity roosts were limited to stands >50 years old, and ~60% were in foliage. Myotis yanbarensis roosted almost entirely in cavities along gulch bottoms and only in stands >70 years old (~1/3 of Kunigami's total forest area). Murina ryukyuana maternity roosts were higher (4.3 ± 0.6 m) than conspecific nonmaternity roosts (2.3 ± 0.5 m; p < .001) and M. yanbarensis roosts (2.7 ± 0.5 m; not significant). Model results were inconclusive. Both species appear to be obligate plant roosters throughout their life cycle, but the less flexible roosting preferences of M. yanbarensis may explain its striking rarity. To conserve these threatened bats, we recommend the following forestry practices: (a) reduce clearing of understory vegetation, (b) refrain from removing trees along streams, (c) promote greater tree cavity densities by protecting old‐growth forests and retaining snags, and (d) refrain from removing trees or understory between April and July, while bats are pupping.