Trailing Surface Research Articles

Ultraviolet Spectroscopy and Photochemistry of SO2/H2O Ices

The presence of sulfur dioxide on the trailing hemisphere of Europa’s surface is well-established, and both its presence and its chemistry are influenced by sulfur ion implantation. Particle irradiation is known to be a significant radiolysis source, particularly on the trailing surface, which is subject to particles in Jupiter’s plasma torus. Photochemistry driven by solar ultraviolet (UV) photons is also significant. To date, most studies have investigated the effects of vacuum UV radiation, while photochemistry at longer wavelengths is less well-studied. This work investigates chemical changes in thin, cryogenic films of SO2/H2O at temperatures and pressures relevant to Europa’s surface when subjected to temperature changes and UV radiation at 147, 206, 254, and 284 nm. Spectra were collected in both the mid-infrared range and the UV range, which elucidates electronic transitions that are less diagnostic but perhaps more applicable to reflectance spectra of solar system bodies. These experiments show irreversible red shifting of the B̃ ← X̃ absorption peak upon heating likely as a result of crystallization and/or thermal chemical reactions. Further, photons with wavelengths up to 284 nm are shown to induce significant chemistry in SO2/H2O mixtures. This in conjunction with the increased solar flux compared to more energetic wavelengths and the strong C̃ ← X̃ and B̃ ← X̃ absorption bands in SO2 suggests that far-UV radiation plays a significant role in the sulfur cycle on Europa.

ВПЛИВ РЕКРЕАЦІЙНОГО НАВАНТАЖЕННЯ НА МОРФОЛОГІЧНІ ОСОБЛИВОСТІ ЛІСОВОЇ ПІДСТИЛКИ (НПП «СКОЛІВСЬКІ БЕСКИДИ» УКРАЇНСЬКІ КАРПАТИ)

The article deals with the analysis of morphological aspects of the forest litter structure on ecological and tourist routes in the mountainous region. The study revealed that the changes in the basic parameters of the forest litter are caused by ground trampling. It was estimated that on trails between 0.5 m and 2 m wide, the stock of forest litter is 1.23-1.5 kg/m², and its capacity is 1.3-1.6 cm. With the supply of fresh foliage on the trails, the L, F and H sub-horizons can be identified there. On trails of 2 to 3 m wide, the stock of forest floor is 0.51-0.91 kg·m², that is almost twice less than on narrower trails. The capacity of the litter on trails more than 2 m wide is 0.3-0.5 cm, of which 0.2-0.4 is the F+H sub-horizon. On slopes with ≥ 15 º, the reserves and capacity of the forest litter in the lower part of the trail are about 10 % greater than in its upper part. Basically, the redistribution of forest litter is observed within a trail and its side. The stock of forest litter on the trail decreases due to the fact that the damaged litter is removed outside the trail. In the spring and summer, the forest litter is washed off by rain and melt water, forming the so-called “rollers” on its road (trail). The capacity and reserves of forest litter on the sidewalks are significantly dependent on the width and direction of the trail. The narrower the trail, the larger are the forest litter reserves and on the contary, the wider the trail, the smaller is the forest litter within the sidewalk. The capacity of the forest litter on the side of the trails of the studied routes ranges from 1.3 to 4.8 cm, and its reserves have increased to 1.44-2.26 kg·m². A composition of tree species, tree layer compactness and terrain play an important role in the formation of forest litter as well. The impact of recreation load on the soil cover was also evaluated. It was established that at the initial stages (of I-II categories) of recreation digression, the forest litter becomes compacted and crushed, forming a powerful F+H sub-horizon and covering the trail surface. As the recreation load increases (III stage/category) the stock of litter in spruce-beech-fir forest in the warm season is less than 1 kg/m².

Bortezomib sensitizes multiple myeloma to NK cells via ER-stress-induced suppression of HLA-E and upregulation of DR5

ABSTRACTAlthough the proteasome inhibitor bortezomib has significantly improved the survival of patients with multiple myeloma (MM), the disease remains fatal as most patients eventually develop progressive disease. Recent data indicate that MM cells can evade bortezomib-induced cell death by undergoing autophagy as a consequence of endoplasmatic reticulum (ER)-stress induced by proteasome inhibition. Here we show that bortezomib sensitizes MM cells to NK cell killing via two distinct mechanisms: a) upregulation of the TRAIL death receptor DR5 on the surface of MM cells and b) ER-stress induced reduction of cell surface HLA-E. The latter mechanism is completely novel and was found to be exclusively controlled by the inhibitory receptor NKG2A, with NKG2A single-positive (NKG2ASP) NK cells developing a selective augmentation in tumor killing as a consequence of bortezomib-induced loss of HLA-E on the non-apoptotic MM cells. In contrast, the expression of classical HLA class I molecules remained unchanged following bortezomib exposure, diminishing the augmentation of MM killing by NK cells expressing KIR. Further, we found that feeder cell-based ex vivo expansion of NK cells increased both NK cell TRAIL surface expression and the percentage of NKG2ASP NK cells compared to unexpanded controls, substantially augmenting their capacity to kill bortezomib-treated MM cells. Based on these findings, we hypothesize that infusion of ex vivo expanded NK cells following treatment with bortezomib could eradicate MM cells that would normally evade killing through proteasome inhibition alone, potentially improving long-term survival among MM patients.

Mulching and water diversion structures on skid trails: Response of soil physical properties six years after harvesting

In recent years, the application of mulch on machine operating trails has gained popularity as a method of reducing post-harvest soil erosion and water runoff following ground-based harvesting operations. Three treatments immediately applied after ground-based skidding operations were sawdust mulch (SM), water diversion structure or contour-felled log erosion barrier (WDS), and untreated/bare trail (U) in May 2011. At the time of skidding, weather conditions had been very dry and warm. The SM treatment was manually spread on the entire trail surface at a rate of 3.65 kg m−2. WDS was created by placing felled logs with diameters ranging from 25 to 30 cm and 4 m in length in a perpendicular direction to the skid trails with the distance between adjacent WDS set at 10 m. This study aimed to determine and compare the effectiveness of three treatments on the recovery of soil physical properties from compacted soil caused during logging operations over a six-year period (from May 2011 to July 2017) in the Hyrcanian forest, north of Iran. Soil bulk density, total porosity, penetration resistance, and rut depth (wheel rut) were measured to assess the recovery process on three abandoned skid trails with varying longitudinal gradients (10%, 20%, and 30%) exposed to different levels of machine traffic (low, medium, and high). On trails with a 10% gradient, the highest recovery values of bulk density (7.8%) and total porosity (8.5%) were observed in the SM treatment, while on the steepest gradients (20 and 30%), the highest recovery values of bulk density (10.9%) and total porosity (12.9%) were found in the WDS treatment. The average recovery of penetration resistance for soil located in the SM and WDS treatments was 19.1% and 10.5%, respectively. Average rut depth recovery, expressed in percent of post-harvest values, was higher on all trail gradients subjected to the WDS treatment (30.6%) as compared to the SM treatment (13.1%). In general, values of soil bulk density, total porosity, penetration resistance and rut depth continued to show signs of machine-induced disturbance over the 6-year monitoring period, compared to the undisturbed area as a benchmark.

Formation of surface trailing counter-rotating vortex pairs downstream of a sonic jet in a supersonic cross-flow

Direct numerical simulations were conducted to uncover physical aspects of a transverse sonic jet injected into a supersonic cross-flow at a Mach number of 2.7. Simulations were carried out for two different jet-to-cross-flow momentum flux ratios ($J$) of 2.3 and 5.5. It is identified that collision shock waves behind the jet induce a herringbone separation bubble in the near-wall jet wake and a reattachment valley is formed and embayed by the herringbone recirculation zone. The recirculating flow in the jet leeward separation bubble forms a primary trailing counter-rotating vortex pair (TCVP) close to the wall surface. Analysis on streamlines passing the separation region shows that the wing of the herringbone separation bubble serves as a micro-ramp vortex generator and streamlines acquire angular momentum downstream to form a secondary surface TCVP in the reattachment valley. Herringbone separation wings disappear in the far field due to the cross-interaction of lateral supersonic flow and the expansion flow in the reattachment valley, which also leads to the vanishing of the secondary TCVP. A three-dimensional schematic of surface trailing wakes is presented and explains the formation mechanisms of the surface TCVPs.

Heat Transfer in a Rotating Cooling Channel (AR = 2:1) With Rib Turbulators and a Tip Turning Vane

Experimental investigation on rotation and turning vane effects on heat transfer was performed in a two-pass rectangular internal cooling channel. The channel has an aspect ratio of AR = 2:1 and a 180 deg tip-turn, which is a scaled up model of a typical internal cooling passage of gas turbine airfoils. The leading surface (LS) and trailing surface (TS) are roughened with 45 deg angled parallel ribs (staggered P/e = 8, e/Dh = 0.1). Tests were performed in a pressurized vessel (570 kPa) where higher rotation numbers (Ro) can be achieved with a maximum Ro = 0.42. Five Reynolds numbers (Re) were examined (Re = 10,000–40,000). At each Reynolds number, five rotational speeds (Ω = 0–400 rpm) were considered. Results showed that rotation effects are stronger in the tip regions as compared to other surfaces. Heat transfer enhancement up to four times was observed on the tip wall at the highest rotation number. However, heat transfer enhancement is reduced to about 1.5 times with the presence of a tip turning vane at the highest rotation number. Generally, the tip turning vane reduces the effects of rotation, especially in the turn portion.

Visualization and analysis of flow structures in an open cavity

A numerical study is performed on the supersonic flow over an open cavity at Mach number of 1.5. A newly developed visualization method is employed to visualize the complicated flow structures, which provide an insight into major flow physics. Four types of shock/compressive waves which existed in experimental schlieren are observed in numerical visualization results. Furthermore, other flow structures such as multi-scale vortices are also obtained in the numerical results. And a new type of shocklet which is beneath large vortices is found. The shocklet beneath the vortex originates from leading edge, then, is strengthened by successive interactions between feedback compressive waves and its attached vortex. Finally, it collides against the trailing surface and generates a large number of feedback compressive waves and intensive pressure fluctuations. It is suggested that the shocklets beneath vortex play an important role of cavity self-sustained oscillation.

Hydrodynamic Lubrication of a Liquid Conducting Film Controlled by Magnetic Pressure at Rail–Armature Interface

When an armature slides along a pair of rails under the action of Lorentz forces, the serious material melted at the interface will appear due to frictional and Joule heating. A liquid conducting film composed of molten metal forms over the rail–armature contact surfaces. Magnetic field was concentrated in the trailing surface of the armature and liquid film due to the velocity skin effect resulting in a large magnetic pressure acting on them in these regions. Magnetic lateral force in the film squeezes the armature legs against the rails in the lateral direction forming a diverging gap. Magnetic pressure in the longitudinal direction propels the armature and liquid film moving at different speeds and could cause a self-acceleration in the film. The traditional lubrication theory suggests that the liquid film flowing along a diverging gap cannot form positive pressure to achieve hydrodynamic lubrication. This paper attempts to investigate whether a diverging film controlled by magnetic pressure can achieve hydrodynamic lubrication and uncover its control mechanism. The film is assumed to be linearly diverging with a specified magnetic pressure controlled at the trailing edge. Analytical solution of pressure distribution is obtained by integrating the generalized 1-D Reynolds equation, taking into account the acceleration of the liquid film. Mechanism controlled by magnetic pressure is analyzed. Furthermore, conditions for generating positive pressure distribution are also obtained. In the end, hydrodynamic lubrication of a diverging film under the influence of magnetic pressure is discussed.

The Murine Natural Cytotoxic Receptor NKp46/NCR1 Controls TRAIL Protein Expression in NK Cells and ILC1s

SummaryTRAIL is an apoptosis-inducing ligand constitutively expressed on liver-resident type 1 innate lymphoid cells (ILC1s) and a subset of natural killer (NK) cells, where it contributes to NK cell anti-tumor, anti-viral, and immunoregulatory functions. However, the intrinsic pathways involved in TRAIL expression in ILCs remain unclear. Here, we demonstrate that the murine natural cytotoxic receptor mNKp46/NCR1, expressed on ILC1s and NK cells, controls TRAIL protein expression. Using NKp46-deficient mice, we show that ILC1s lack constitutive expression of TRAIL protein and that NK cells activated in vitro and in vivo fail to upregulate cell surface TRAIL in the absence of NKp46. We show that NKp46 regulates TRAIL expression in a dose-dependent manner and that the reintroduction of NKp46 in mature NK cells deficient for NKp46 is sufficient to restore TRAIL surface expression. These studies uncover a link between NKp46 and TRAIL expression in ILCs with potential implications in pathologies involving NKp46-expressing cells.

Experimental investigations and correlation development of convective heat transfer in a rotating smooth channel

An experimental study has been carried out to investigate the effects of Coriolis force and centrifugal buoyancy force on convective heat transfer in a smooth cooling channel under rotating condition in a new rotation facility. The main motivation behind this work is to obtain required data for developing heat transfer correlations based on rotating state. In accordance with the open literature, four parameters, i.e.s Reynolds number, Rotation number, coolant Density Ratio and main flow direction were selected to study the influence on local heat transfer coefficient. Therefore, the investigation considered Reynolds number (Re) ranging from 5000 to 12,000, Rotation number (Ro) in the range of 0–0.15, Inlet Density Ratio (DR) between 0.04 and 0.1 and at the entry developing region of a square smooth channel in a new rotation test bench. Comprehensive experiment have been conducted to collect data on the local Nusselt number at the leading and trailing walls. The results show that the local heat transfer rate is enhanced by rotation on the trailing surface and reduced on the leading surface in outward flow due to symmetrical secondary vortex generated by Coriolis force. The centrifugal buoyancy effect is favorable to the heat transfer enhancement on both walls. Also, by utilizing the extensive experimental data, correlations for the local Nusselt number have been updated for the leading and trailing walls in ranges of the mentioned flow parameters, which can be used as an internal cooling boundary condition for numerical analysis of thermal stresses and cooling efficiency maximization for gas turbine blades.

These Boardwalks Were Made for Bushwalking: Disentangling Grounds, Surfaces, and Walking Experiences

What matter is walking ground made of? And how does such ground matter? What is the relationship between walking surfaces and people’s experience of natural landscapes? And how do different ground surfaces enact different meshworks of conservation politics, mobility, and tourism infrastructure? Drawing from nonrepresentational theory and from audiovisual fieldwork conducted in and around Australia’s Cradle Mountain, part of the Tasmanian Wilderness World Heritage Area, this article and its accompanying video focus on the materials of walking trails to understand the relations among walking, the built environment, and the sensory and affective experience of place. Arguing that trails and trail surfaces—and boardwalks in particular—serve as influential material conduits for variously contested outdoor recreation mobilities, this article develops the argument that pathways are elements in the world’s transformation of itself.

Heat Transfer in a Rib and Pin Roughened Rotating Multipass Channel With Hub Turning Vane and Trailing-Edge Slot Ejection

A multipassage internal cooling test model with a 180 deg U-bend at the hub was investigated. The flow is radially inward at the inlet passage while it is radially outward at the trailing edge passage. The aspect ratio (AR) of the inlet passage is 2:1 (AR = 2) while the trailing edge passage is wedge-shaped with side wall slot ejections. The squared ribs with P/e = 8, e/Dh = 0.1, α = 45 deg, were configured on both leading surface (LE) and trailing surface (TR) along the inlet passage, and also at the inner half of the trailing edge passage. Three rows of cylinder-shaped pin fins with a diameter of 3 mm were placed at both LE and TR at the outer half of the trailing edge passage. For without turning vane case, heat transfer on LE at hub turn region is increased by rotation while it is decreased on the TR. The presence of turning vane reduces the effect of rotation on hub turn portion. The combination of ribs, pin-fin array, and mass loss of cooling air through side wall slot ejection results in the heat transfer coefficient gradually decreased along the trailing edge passage. Correlation between regional heat transfer coefficients and rotation numbers is presented for with and without turning vane cases, and with channel orientation angle β at 90 deg and 45 deg.

Experimental and numerical investigation of flight dynamics of a generic lambda wing configuration

The development and comparison of aerodynamic simulation models for the inclusion in an open-loop stability & control model based on both experimental and numerical data are presented. Specifically, the work is focused on the effectiveness of the Kestrel simulation tools in replicating the aerodynamic coefficient data from wind tunnel experiments of a generic lambda wing configuration with four trailing edge control surfaces. Simulation conditions correspond to the angles of attack in range of −5∘ to 10∘ at assumed cruise Mach number of 0.7. These simulations include a clean configuration with no control surface deflection and when inboard/outboard control surfaces are deflected −10∘, −5∘, 5∘, and 10∘. Single and overset grids are used to simulate the control surface deflections. Predicted aerodynamic data are collected in form of look-up tables and are run in a Matlab/Simulink program to determine stability and control properties of the vehicle. The vehicle stability and control characteristics are then compared with the results of running experimental coefficient values through the same program. The results show that numerical predictions of the test case considered depend heavily on the geometry details and numerical setup, e.g. turbulence modeling, grid refinement, integration scheme, time step, etc. and therefore do not match experimental data at all tested conditions. In addition, the stability and control investigation of the vehicle using these data confirms that the differences between simulations and measurements could lead to significant changes in the evaluation of vehicle's stability and control characteristics. The simulation predictions of this work, therefore, cannot fully replace the need for experiments to determine the vehicle's stability and control, however they help to provide insight into flow physics and to direct/make best use of wind tunnel experiments.

Two-dimensional heat transfer distribution in a rotating smooth rectangular channel with four surface heating boundary condition

In this study, two-dimensional heat transfer distribution on the leading surface and trailing surface in a rotating smooth channel with typical boundary condition of four surface heating was investigated experimentally for the first time. The Reynolds number, based on channel hydraulic diameter (80 mm) and the bulk mean velocity, ranges from 15,000 to 30,000, and the highest rotation number is 0.359 with the Reynolds number of 15,000. The mean density ratio is about 0.11 in this work. The obtained result showed that rotation has an important effect on the heat transfer distribution along the span-wise direction. On the leading side, rotation-induced secondary flow makes the Nu/Nu0 at the edge area of the wall surface (Z/D = 0 and Z/D = 1) is higher than that on the middle area (Z/D = 0.5). On the trailing surface, the trend of Nu/Nu0 ratio along the span-wise direction is reversed. Along the stream-wise direction, the Nu/Nus ratio increases with the rotation number monotonously on the trailing side. Howev...

TrailSense

Trail surface information is critical in preventing from the mountain accidents such as falls and slips. In this paper, we propose a new mobile crowdsensing system that automatically infers whether trail segments are risky to climb by using sensor data collected from multiple hikers’ smartphones. We extract cyclic gait-based features from walking motion data to train machine learning models, and multiple hikers’ results are then aggregated for robust classification. We evaluate our system with two real-world datasets. First, we collected data from 14 climbers for a mountain trail which includes 13 risky segments. The average accuracy of individuals is approximately 80%, but after clustering the results, our system can accurately identify all the risky segments. We then collected an additional dataset from five climbers in two different mountain trails, which have 10 risky segments in total. Our results show that the model trained in one trail can be used to accurately identify all the risky segments in the other trail, which documents the generalizability of our system.

Reconstruction of chronic Achilles tendon rupture with Achilles tendon allograft

This study presented an extensive analysis of the influence of chord-to-thickness ratios on unsteady behaviors of the separated flow and their coupling with wall-pressure fluctuations at the Reynolds number ReD=1.58×104. Three systems with different chord-to-thickness ratios were chosen for comparison: L/D = 3.0, 6.0, and 9.0. The separated flow fields and wall-pressure fluctuations were measured using planar Particle Image Velocimetry (PIV) operating at 1 Hz and a microphone array sampling at 1 kHz, respectively. The distributions of the turbulent kinetic energy and the reverse-flow intermittency indicated that the shortest plate (L/D = 3.0) was subjected to full coverage of the separated flow. In the moderate system (L/D = 6.0), the time-averaged reattachment station was determined to be x/D = 4.75, while in 7% of all realizations the fluid close to the trailing edge surface remained slightly reversed due to the unsteady reattachment of the separated shear layer to the trailing edge and to irregular trailing edge vortex shedding. However, the separated flow always reattached on the plate’s surface in the longest system L/D = 9.0. The measured wall-pressure fluctuations demonstrated combinative influences of hydrodynamic pressure of the large-scale vortical structures above the plate and acoustic excitation propagated by the energetic unsteady wake. This resulted in the salient phase changeover characteristics of the correlative patterns near x/D = 1.5 in the shortest system, L/D = 3.0. Close to the leading edge, the wall-pressure fluctuations in the L/D = 6.0 system were over-exposed to acoustic excitation propagated by the unsteady wake behind the trailing edge, while in the longest system, L/D = 9.0, such influences were relatively attenuated. Proper Orthogonal Decomposition (POD) analysis was performed on the down-sampled wall-pressure fluctuations paired with the flow fields, resulting in a series of energetic flow structures and their corresponding wall-pressure fluctuation profiles. Subsequently, the conditional averaging technique was applied to determine the relationship between the spatial characteristics of the large-scale vortical structures and profiles of the wall-pressure fluctuations.

Numerical study on the effect of the diffuser blade trailing edge profile on flow instability in a nuclear reactor coolant pump

The shedding flow structures from the diffuser blade trailing edge, usually known as Von Kármán vortices, are complicated and crucial to the safe operation of the nuclear reactor coolant pump (RCP), if the shedding frequency reaches the resonant frequency of the diffuser. In the present study, numerical investigation is conducted to analyze the effect of the diffuser blade trailing edge (BTE) profile on the flow instability in a nuclear reactor coolant pump. Five typical diffuser BTEs are analyzed including original trailing edge (OTE), circular trailing edge (CTE), suction surface trailing edge radius 45mm (STER 45), suction surface trailing edge radius 60mm (STER 60) and suction surface trailing edge radius 75mm (STER 75). Results show that by changing the diffuser BTE profile, the vortex shedding intensity from the trailing edge would be diminished, and unsteady flow structures in the spherical casing are more uniform with the well modified diffuser BTE profile. When adopting the cases of STER 45, STER 60 and STER 75, pressure pulsations decrease at the diffuser outlet, but increase at the right side of spherical casing wall. From axial-vorticity distribution, it is indicated that the appropriate BTE profile can effectively prevent flow separation and change evolution of separate flow especially near the discharge nozzle. Besides, it would also diminish Von Kármán vortices from the diffuser BTE, and improve the RCP hydraulic efficiency.

Plasma polymerized acetylene deposition using a return corona enhanced plasma reactor

A corona based weakly ionized plasma source was developed to deposit plasma polymerized acetylene coating at atmospheric pressure. The plasma source included a distinctive point-to-point geometry consisting of an array of high voltage needles and an array of protrusions placed over a grounded screen. The geometry facilitated various corona discharge modes that included return corona to contribute plasma polymerized acetylene deposition downstream from the corona section. Scanning probe techniques were used to investigate deposition on both the leading surface and the trailing surface of substrates. Deposition was initiated as distinct nodules that merged to form a thin plasma polymerized coating.

Anisotropic Ejection from Active Asteroid P/2010 A2: An Implication of Impact Shattering on an Asteroid*

Abstract We revisited a mass ejection phenomenon that occurred in asteroid P/2010 A2 in terms of the dynamical properties of the dust particles and large fragments. We constructed a model assuming anisotropic ejection within a solid cone-shaped jet and succeeded in reproducing the time-variant features in archival observational images over ∼3 years from 2010 January to 2012 October. We assumed that the dust particles and fragments were ejected in the same direction from a point where no object had been detected in any observations, and the anisotropic model explains all of the observations including (i) the unique dust cloud morphology, (ii) the trail surface brightness, and (iii) the motions of the fragments. Our results suggest that the original body was shattered by an impact with specific energy J kg−1, and remnants of slow antipodal ejecta (i.e., anisotropic ejection in our model) were observed as P/2010 A2. The observed quantities are consistent with those obtained through laboratory impact experiments, supporting the idea that the P/2010 A2 event is the first evidence of the impact shattering that occurred in the present main asteroid belt.

The Upper Mississippian Occupation at the Collier Lodge Site (12PR36)

Abstract The Upper Mississippian Fisher/Huber occupations of northwestern Indiana are part of the easternmost extension of Oneota. Excavations at the Collier Lodge site (12PR36) found 18 Upper Mississippian features from a seasonal encampment on the edge of the Kankakee Marsh. The ceramic assemblage and radiocarbon dates indicate the site was created during the late fifteenth century, placing it in the northwestern Indiana temporal sequence between the previously known Fifield site occupation and the Huber phase component at the Griesmer site. The ceramic decorative elements include relatively low proportions of medium trailing and cordmarking, with higher proportions of wide trailing and smooth surfaces, suggesting a very late pre-Huber occupation (fine trailing is virtually absent). The assemblage could also reflect a Late Fisher occupation followed after a short period of time by a terminal Fisher/early Huber occupation. Oneota sites in northwestern Indiana appear to have been relatively rare, widely distributed, small, and seasonal.