Thin Margin Research Articles

Primum Non Nocere: A Rare Case of Amplatzer Erosion and Cardiac Pseudoaneurysm with Multimodality Imaging

Complications of septal-occluder devices include erosion, perforation, and embolization, which are most commonly caused by oversized devices or thin rim margins. Cardiac pseudoaneurysm is a rare phenomenon that forms as a result of device erosion into the myocardium. Although this is often an incidental finding, they are at risk for rupture. (Level of Difficulty: Intermediate.)

Performance comparison between waverider and wide-speed-range gliding vehicle based on CFD approaches

Wide-speed-range gliding vehicle (WSRGV) is designed to adapt to the variable cruising environment that hypersonic vehicles will encounter during the mission implementation. Based on the cone-derived theory, a novel design technique of WSRGV has been developed. Theoretically, the functional relationship between cone-derived waverider’s volumetric efficiency and its design Mach number can be built through sampling approach as long as the geometries of design conical shock wave and the upper base curve are fixed. Based on the functional relationship, a cone-derived waverider that owns the same volumetric efficiency with a giving WSRGV can be acquired. This paper compared the aerodynamic performance between WSRGV and the cone-derived waverider sharing the same volumetric efficiency in a wide Mach number range. Their aerodynamic properties versus angle of attack have also been compared under the waverider’s design Mach number. The obtained result shows that WSRGV shares similar aerodynamic performance with the cone-derived waverider with the same volumetric efficiency. The aero-surfaces in the margin area of this kind of configuration have a larger contribution to the lift-to-drag ratio in comparison with the aero-surfaces in the central area. The configuration with a thick central body and thin margin place owns not only better aerodynamic performance but also better loading property.

Marginal Integrity of Glass Ceramic Laminate Veneers Produced Through Different CAD/CAM Milling Protocols: In-Vitro Study

Statement of the problem: The conservative nature of the labial ceramic veneers necessitates minimum amount of tooth reduction with thin peripheral margins. Since construction time of restorations is becoming a determinant factor together with accuracy, the effect of three different CAD/CAM milling protocols that depend on the time factor deserves to be assessed.Purpose: The purpose of this investigation was to evaluate the effect of three different CAD/CAM milling protocols; namely normal, fast, and two-step milling on the peripheral marginal accuracy of glass-ceramic laminate veneers.Materials and Methods: A maxillary central incisor acrylic tooth was chosen to serve as a die for veneer construction. Acrylic tooth preparation was done to receive incisal feather edge design for the ceramic veneer. A total of thirty laminate veneer restorations were constructed from IPS e.max CAD glass ceramic using the CAD/CAM technology with three different milling protocols. The veneers were divided into the following groups according to the selected milling protocol; Group 1: Ten veneers constructed using the normal milling protocol, Group 2: Ten veneers constructed using the fast milling protocol, Group 3: Ten veneers constructed using the two-step milling protocol. The milled veneers were subjected to crystallization process according to manufacturer’s instructions then they were checked on their corresponding die for proper adaptation and seating. For proper assessment of the vertical marginal gap, the veneers were fixed on the master die using one drop of adhesive placed centrally to stabilize the veneers in their place during the measuring procedure. The vertical marginal gap distance of each ceramic was measured using a stereomicroscope at magnification X45. The measurements were done along the peripheral circumference for all the veneer margins (mesial, distal, cervical and incisal). Measurement at each point was repeated five times. A digital image analysis system was used for assessing and evaluating vertical marginal gap width. The mean vertical marginal gap distance was calculated and then tabulated for the statistical analysis of the data. Results: Effect of milling protocol: The two-step milling protocol showed the statistically significant lowest mean marginal gap distance (33.2 ± 6.3 μm) while both the normal and fast milling protocols showed the statistically significant highest mean marginal gap distances with no statistically significant difference between them. (40 ± 7.5 μm and 41.2 ± 4.9 μm respectively) Effect of surface: The cervical surface recorded the statistically significant lowest mean marginal gap distance (34 ± 6.5 μm) while the distal surface recorded the highest mean marginal gap distance (41.6 ± 8.6 μm) with non-statistically significant difference from incisal (37.2 ± 4.6 μm) and mesial surface (39.7 ± 6.4 μm).Conclusions: Within the limitations of this in-vitro study, the following conclusions were drawn: 1) Marginal discrepancy of all groups fell within the clinically acceptable value, thus the three milling protocols can be safely used. 2)Veneers fabricated using the two-step milling protocol exhibited the least marginal discrepancy among other experimental groups, thus it can be used as the protocol of preference if restoration accuracy is of utmost importance. 3) Since there was no significant difference between normal and fast milling protocols regarding marginal discrepancy, therefore fast milling can be recommended for veneer fabrication if chairside time is of prime importance in some cases. 4) Cervical marginal discrepancy was found to have the least value compared to other surfaces

Cost Economies for an Airline: An Analysis of Airlines’ Operating Costs

This study focuses on analyzing the variables affecting the average operating cost per aircraft movement. Since airlines around the world are operated on thin profit margins and with increasing competition from Low Cost Carriers it will be important for an airline to get a complete understanding about their operating cost structure. The aim of this study is to suggest an airline of actions to reduce their operating cost and will differentiate the cost structures of Low Cost Carriers and Full Service Carriers. This study was conducted for 20 airlines which were operating in Asia Pacific region. Published financial and statistical data were used for analysis and a parametric approach was used. The results of this study do not suggest economies of scale for the airline, which is to have higher number of aircraft to reduce cost.

Cost Economies for an Airline: An Analysis of Airlines’ Operating Costs

This study focuses on analyzing the variables affecting the average operating cost per aircraft movement. Since airlines around the world are operated on thin profit margins and with increasing competition from Low Cost Carriers it will be important for an airline to get a complete understanding about their operating cost structure. The aim of this study is to suggest an airline of actions to reduce their operating cost and will differentiate the cost structures of Low Cost Carriers and Full Service Carriers. This study was conducted for 20 airlines which were operating in Asia Pacific region. Published financial and statistical data were used for analysis and a parametric approach was used. The results of this study do not suggest economies of scale for the airline, which is to have higher number of aircraft to reduce cost.

Predicting retail shrink from performance pressure, ethical leader behavior, and store‐level incivility

SummaryRetail shrink, a form of inventory loss due primarily to employee theft and shoplifting, is a growing concern for retailers. Prior work on shrink has taken primarily an individual‐level focus to understanding this problem but has yet to really explore how the business context impacts shrink. The current study addresses this need by delineating and testing a unit‐level (i.e., between‐stores) conceptual model, wherein we examine the influence of performance pressure, ethical leader behavior, and store‐level incivility on shrink in a field study of 111 U.S. retail stores. Results demonstrate that performance pressure and ethical leadership interact to influence store‐level incivility. Further, stores with higher incivility also had higher levels of shrink. A focus on the contextual predictors of shrink provides timely insights into the role of performance pressure and leadership on store‐level incivility and consequently on retail shrink. In light of increasingly thin margins in the retail industry, the evidence on how pressure to perform and ethical leadership influences retail shrink may offer a solution to retailers looking to stem financial losses by promoting civility in the workplace.

New lichenized Arthoniales and Ostropales from Mexican seasonally dry tropical forest

Twelve new lichenized species are described in Arthoniales and Ostropales from seasonally dry tropical forest in Mexico: eight in Graphidaceae, one in Gomphillaceae, and one each in Arthoniaceae, Roccellaceae, and Opegraphaceae. The new species are: Acanthothecis alba Herrera-Camp., Barcenas-Pena & Lucking, differing from A. poitaeoides in the erumpent to prominent ascomata with partially exposed disc and the relatively broader ascospores; Bactrospora lecanorina Herrera-Camp., Altamirano & Lucking, differing from the other species with patellarioides-type ascospores by the zeorine ascomata, in combination with narrow ascospores; Cryptothecia chamelensis Herrera-Camp., Bautista & Lucking, differing from C. inexpectata and C. irregularis in the perlatolic acid chemistry and the much smaller ascospores; Fissurina aperta Herrera-Camp., Barcenas-Pena & Lucking, differing from F. adscripturiens and F. novae-zelandiae by its exposed, disc and thin, erect margins; F. cinereodisca Altamirano, Colin & N.Sanchez, differing from F. furfuracea in the shorter ascomata with grey disc and thin, margin; F. jaliscoensis Herrera-Camp., Barcenas-Pena & Lucking, differing from F. subnitida in the shorter lirellae with exposed disc and thin margins; F. reticulata R. Miranda, Herrera Camp. & Lucking, differing from F. tuckermaniana by its muriform ascospores; F. tenuimarginata Herrera-Camp., Barcenas-Pena & Lucking, differing from F. cinereodisca in the smaller lirellae with yellowish-translucent disc and thinner margin; Gyalideopsis caespitosa Barcenas-Pena, Herrera-Camp. & Lucking, differing from other species of the genus in the initially zeorine apothecia and the sessile hyphophores with caespitose diahyphae; Ocellularia tomatlanensis Herrera-Camp., Colin & Lucking, differing from other Ocellularia species with small, transversely septate, hyaline ascospores and protocetraric acid by the absence of a columella; Phaeographis sarcographoides Herrera-Camp., N.Sanchez & Lucking, differing from other species of Phaeographis with inspersed hymenium, 3-septate ascospores, and lack of secondary substances, in the robust, prominent to sessile ascomata with often dissected disc; and Vigneronia mexicana Herrera-Camp., Bautista & Lucking, sp. nov., differing from V. spierii in the prominent to sessile ascomata with brown margin and light grey-pruinose disc. The new combination Vigneronia caceresiana (Kalb & Aptroot) Lucking & Herrera-Camp., comb. nov., is also proposed.

Choice-based dynamic time slot management in attended home delivery

E-grocers with an attended home delivery service model operate in a highly competitive market characterized by thin profit margins. To ensure a profit-maximizing delivery schedule, the requirements for the joint management of demand and the vehicle routes are substantial. Therefore, we study an e-grocer’s operational problem of managing demand by means of dynamic time slot allocation. The purpose of dynamically allocating time slots is to influence customers’ choices by offering a selection of time slots to a customer request, such that the overall expected profit of the resulting delivery schedule is maximized. The time slot offer decisions mainly depend on a request’s opportunity cost. Hence, we first propose a mixed-integer linear program to approximate this opportunity cost, which scales linearly with the number of decision variables. In this approximation, we consider the consequences of expected time slot offer decisions for future customers on the final delivery schedule. We explicitly incorporate customer choice behavior using a generalized attraction model. Second, we propose a non-linear binary program and its linearization based on the underlying choice model to make time slot offer decisions using the approximated opportunity cost. Due to the formulation’s structural properties, it can be efficiently solved. In a computational study, we show the superiority of our approach in comparison to benchmarks applied in the academic literature and its applicability in an online environment.

"Teflon tape technique": synergy between isolation and lucidity.

The aim of this article is to introduce and illustrate the "Teflon tape technique," which provides good lucidity in combination with excellent isolation of the working field. It is intended to serve as a supplement to the gold standard rubber dam for the adhesive working dental practitioner. Primarily, the Teflon tape technique (Teflon is a registered trademark, and not affiliated with Teflon tape) is particularly suitable for the adhesive cementation of restorations with very thin margins. It allows free access to subgingival areas with variable gingival retraction. Furthermore, this principle can also be applied to other indications, such as Class V restorations or deep core buildups. The technique described is therefore flexible and easy to use. This combination allows a fast integration of the Teflon tape technique into the daily workflow of the dental practitioner.

An Innovative Technique to Simplify and Improve Pattern Fabrication for Digital Somatoprosthesis

ABSTRACT Introduction Patterns for somatoprostheses are conventionally made of modeling wax. The rigidity, brittle nature, reduced edge strength, and susceptibility to distortion of this wax often leads to failure in achieving marginal thinning and desired aesthetics. Technique A technique for fabrication of digital somatoprosthetic wax patterns with thin accurate margin by incorporation of a vacuum-formed polyvinyl chloride (PVC) template is described. Results and Discussion The technique helps in overcoming limitations of an all-wax pattern and improves accuracy and aesthetics of outcomes. Conclusions Incorporation of a PVC template in a somatoprosthetic wax pattern is a valuable technique to achieve good aesthetics and accuracy with the prosthesis.

Invited commentary

During the last three decades, vascular surgeons have successfully introduced and embraced a new, minimally invasive approach for the treatment of abdominal aortic aneurysms using endovascular aneurysm repair (EVAR). Whereas countless patients have benefited from EVAR, it is not without its limitations, which include a critical need for lifelong follow-up, a significant reintervention rate that does not plateau over time, and the increased cost. In this month's Journal of Vascular Surgery, Itoga and colleagues take an important step toward developing strategies to mitigate the costs associated with EVAR treatment. They target three primary drivers of cost: device costs, radiology costs, and preprocedure admission costs. The last two are easily addressed and generalizable (radiology costs: decrease the number of computed tomography scans when possible and do not order three-dimensional postprocessing unless necessary; preprocedure admission costs: do not admit patients before the day of surgery). However, bringing device costs down remains a significant challenge for many institutions. As previous publications have shown, the primary driver of cost in their study is attributable to the EVAR device.1Stone D.H. Horvath A.J. Goodney P.P. Rzucidlo E.M. Nolan B.W. Walsh D.B. et al.The financial implications of endovascular aneurysm repair in the cost containment era.J Vasc Surg. 2014; 59: 283-290, 290.e1Abstract Full Text Full Text PDF PubMed Scopus (55) Google Scholar What is unique and important about this study is the way in which they went about trying to reduce their device costs using the Vascular Quality Initiative (VQI). Whereas the VQI has previously been demonstrated to be a powerful engine for collaborative research and measuring quality by benchmarking risk-adjusted outcomes between sites and regions, before this study, the VQI has not been used as a tool for cost containment. By leveraging the VQI platform, 18 sites participated in the Society for Vascular Surgery EVAR Cost Demonstration Project and shared cost data.2Lemmon G.W. Neal D. DeMartino R.R. Schneider J.R. Singh T. Kraiss L. et al.Variation in hospital costs and reimbursement for endovascular aneurysm repair: a Vascular Quality Initiative pilot project.J Vasc Surg. 2017; 66: 1073-1082Abstract Full Text Full Text PDF PubMed Scopus (17) Google Scholar This effort revealed threefold variation in EVAR device costs across sites and enabled the authors' institution to engage in aggressive, informed negotiations with vendors, resulting in a 31% reduction in device costs per case. Given the thin margins associated with EVAR, a 31% reduction in device costs can be the key difference in the procedure's yielding a positive contribution margin (eg, profit) or a negative contribution margin (eg, loss). This study also highlights an important paradigm change that is occurring at more and more centers across the United States: physicians need to play an active role in the effort to reduce costs.3Aiello F.A. Judelson D.R. Messina L.M. Indes J. FitzGerald G. Doucet D.R. et al.A multidisciplinary approach to vascular surgery procedure coding improves coding accuracy, work relative value unit assignment, and reimbursement.J Vasc Surg. 2016; 64: 465-470Abstract Full Text Full Text PDF PubMed Scopus (19) Google Scholar What remains unclear from this study is how generalizable this effort may be to the other (approximately 450) sites that participate in the VQI but that are not participating in the Society for Vascular Surgery EVAR Cost Demonstration Project. This represents an important opportunity for the Society for Vascular Surgery and VQI leadership to recognize the importance of this study and to work toward putting these effective negotiating tools into the hands of all participating VQI sites. The opinions or views expressed in this commentary are those of the authors and do not necessarily reflect the opinions or recommendations of the Journal of Vascular Surgery or the Society for Vascular Surgery. Episode-based cost reduction for endovascular aneurysm repairJournal of Vascular SurgeryVol. 69Issue 1PreviewEffective strategies to reduce costs associated with endovascular aneurysm repair (EVAR) remain elusive for many medical centers. In this study, targeted interventions to reduce inpatient EVAR costs were identified and implemented. Full-Text PDF Open Archive

Randomized Product Display (Ranking), Pricing, and Order Fulfillment for E-commerce Retailers

Problem definition: We study a joint product framing and order fulfillment problem with both inventory and cardinality constraints faced by an e-commerce retailer. There is a finite selling horizon and no replenishment opportunity. In each period, the retailer needs to decide how to “frame” (i.e., display, rank, price) each product on her website as well as how to fulfill a new demand. Academic/Practical Relevance: E-commerce retail is known to suffer from thin profit margins. Using the data from a major U.S. retailer, we show that jointly planning product framing and order fulfillment can have a significant impact on online retailers’ profitability. This is a technically challenging problem as it involves both inventory and cardinality constraints. In this paper, we make progress toward resolving this challenge. Methodology: We use techniques such as randomized algorithms and graph-based algorithms to provide a tractable solution heuristic which we analyze through asymptotic analysis. Results: Our proposed randomized heuristic policy is based on the solution of a deterministic approximation to the stochastic control problem. The key challenge is in constructing a randomization scheme that is easy to implement and that guarantees the resulting policy is asymptotically optimal. We propose a novel two-step randomization scheme based on the idea of matrix decomposition and a re-scaling argument. Managerial Implications: Our numerical tests show that the proposed policy is very close to optimal, can be applied to large-scale problems in practice, and highlights the value of jointly optimizing product framing and order fulfillment decisions. When inventory across the network is imbalanced, the widespread practice of planning product framing without considering its impact on fulfillment can result in high shipping costs, regardless of the fulfillment policy used. Our proposed policy significantly reduces shipping costs by using product framing to manage demand so that it occurs close to the location of the inventory.

The genus Halegrapha new to Hawaii, with the new and potentially endemic species H. paulseniana and an updated checklist of Hawaiian lirellate Graphidaceae (Ascomycota: Ostropales)

The new species Halegrapha paulseniana Luch & Lucking is described from Hawaii, which constitutes the first report of the genus for this archipelago. The new species differs from the most similar taxon, H. mexicana, in the much larger lirellae featuring an apically complete, thin thalline margin, and from all other species in the genus by its laterally mostly uncarbonized excipulum. We provide nomenclatural updates for the 70 species of lirellate Graphidaceae reported from Hawaii so far, introducing the following nomenclatural novelties: Allographa gracilescens (Redinger) Luch & Lucking, comb. & stat. nov., Fissurina homichlodes (Redinger) Luch & Lucking, comb. nov., Fissurina stromatoides (H. Magn.) Luch & Lucking, comb. nov., Fissurina zahlbruckneriana Luch & Lucking, nom. nov., Phaeographis caesiohians (Nyl.) Luch & Lucking, comb. nov., Phaeographis faurieana (Zahlbr.) Luch & Lucking, comb. nov., Phaeographis fulgurata (Fee) Luch & Lucking, comb. nov., Phaeographis oscitans (Tuck.) Luch & Lucking, comb. nov., Phaeographis rhodoplaca (Mull. Arg.) Luch & Lucking, comb. nov., Platygramme kaalensis (Tuck.) Luch & Lucking, comb. & stat. nov., Platygramme tumulata (Nyl.) Luch & Lucking, comb. nov. and Sarcographa dendroides (Leight.) Tabaquero, Bawingan & Lucking, comb. nov. (validated from an earlier, intended new combination that was not validly published).

The Passa Três lode gold deposit (Paraná State, Brazil): An example of structurally-controlled mineralisation formed during magmatic-hydrothermal transition and hosted within granite

The Passa Três granite is a NNE-SSW elongated shape intrusion located in the Paraná State (southern Brazil). This intrusion was emplaced within metapelites of the Mesoproterozoic Votuverava Group, which are part of the N040°E trending Lancinha Shear Zone. Gold mineralisation within the Passa Três granite is held by meter-scale quartz veins forming orebodies with variable massive, banded, sheared and/or brecciated internal textures. Structural data indicate the existence of two orthogonal directions of structures, N-S and E-W, dipping 60–75°W and 45–70°S respectively. Mineralised veins contain, in addition to the quartz of the gangue, and in chronological order: fluorite, pyrite, chalcopyrite, gold, aikinite, molybdenite, muscovite, carbonate and baryte. Gold occurs as native grains within fractures that affect pyrite, commonly associated with chalcopyrite and aikinite. Quartz veins are sometimes bordered by aplitic dykes. Additionally, some of the veins exhibit a thin margin of K-feldspar minerals that could represent the early stage of vein formation. These observations, the presence of Unidirectional Solidification Textures (UST), along with abundant expression of pegmatite-rich pockets within granite that crops out close to the surface allow the reconstruction of the granite architecture in terms of late magmatic evolution, magmatic-hydrothermal transition and position of the cupola. N-S and E-W systems are interpreted to be contemporaneous and conjugate. Normal displacements are predominant and main mineralised veins are essentially located within extensional pull-apart structures. The structural model suggests that the normal faults were initiated along former low-angle planes associated with aplite and/or early quartz veins that subsequently controlled the opening of the pull-apart structures that represent the economic orebodies. Zircon from the granite and muscovite grains from mineralised veins were dated by U-Pb and Ar-Ar methods, respectively. Zircons from the main facies (medium grained: GEM and microgranite: GEF) provided undistinguishable ages which were pooled to give an age of 611.9 ± 3.6 Ma. A less abundant, leucocratic facies (“white granite”: GEB) yielded a significantly younger age of 592.8 ± 7.1 Ma. Muscovites from quartz veins gave Ar-Ar ages of 612.9 ± 2 to 608.8 ± 2 Ma (transitional vein with a K-feldspar border), 611.7 ± 2 to 608.8 ± 2 Ma (mineralised veins) and 608.4 ± 2 Ma (barren quartz vein). Thus, the Passa Três granite and its gold mineralisation appear to represent a unique example of an intrusion-related gold system in which the mineralisation concentrates in the core of the magmatic intrusion in the form of meter-scale veins strongly controlled by tectonics.

Flowering phenology and trap pollination of the rare endemic plantCeropegia thaithongiaein montane forest of northern Thailand

Although Ceropegia species are well known for their complex pitfall flowers that temporarily imprison their pollinators, various aspects of their pollination ecology are still unknown. This study investigated flowering phenology, functional floral traits, and insect visitation in a natural population of a rare endemic lithophyte, Ceropegia thaithongiae Kidyoo. Flowering of C. thaithongiae was not synchronous but staggered. Anthesis lasted mostly 1–2 days, but its duration was shorter in flowers with a pollinium inserted into the stigmatic chamber. Several different insects visited flowers, but only chloropid and milichiid flies were effective pollinators. At anthesis, the epithelial osmophores on the corolla lobes emitted a floral scent that was simple in composition. Nectar of high viscosity was exuded from the nectaries hidden behind the guide rails. When transported by an insect, the pollinarium was attached to bristles on the mouthparts. Size and shape of the thin pellucid margin of the pollinium enable it to fit into the stigmatic chamber in a lock-and-key arrangement. The pollen transfer efficiency was 6.8%. The plant’s staggered flowering and pollination-induced ending of anthesis are advantageous in decreasing competition for pollinators when flower-visiting insects are scarce.

CAD/CAM Ceramic Restorative Materials for Natural Teeth

Advances in computer-aided design (CAD) / computer-aided manufacturing (CAM) technologies and their ease of application enabled the development of novel treatment concepts for modern prosthodontics. This recent paradigm shift in fixed prosthodontics from traditional to minimally invasive treatment approaches is evidenced by the clinical long-term success of bonded CAD/CAM glass-ceramic restorations. Today, defect-oriented restorations, such as inlays, onlays, and posterior crowns, are predominately fabricated from glass-ceramics in monolithic application. The variety of CAD/CAM ceramic restorative systems is constantly evolving to meet the increased demands for highly aesthetic, biocompatible, and long-lasting restorations. Recently introduced polymer-infiltrated ceramic network CAD/CAM blocks add innovative treatment options in CAD/CAM chairside 1-visit restorations. The material-specific high-edge stability enables the CAD/CAM machinability of thin restoration margins. Full-contour zirconia restorations are constantly gaining market share at the expense of bilayered systems. Advancements in material science and bonding protocols foster the development of novel material combinations or fabrication techniques of proven high-strength zirconia ceramics. CAD/CAM applications offer a standardized manufacturing process resulting in a reliable, predictable, and economic workflow for individual and complex teeth-supported restorations. More evidence from long-term clinical studies is needed to verify the clinical performance of monolithic polymer-infiltrated ceramic network and zirconia teeth-supported minimally invasive and extensive restorations.

The Value of Disclosing Product Availability on Retail Platforms

Problem definition: Online retailers disclose product availability to influence customer decisions, as a form of pressure selling designed to compel customers to rush into a purchase. Can the revelation of this information drive sales and profitability? We study the effect of disclosing product availability on market outcomes---product sales and returns---and identify the contexts where this effect is most powerful. Academic/practical relevance: Increasing sell-out is key for online retailers to remain profitable in the presence of thin margins and complex operations. We provide insights on how their information disclosure policy---something they can tailor at virtually no cost---can contribute to this important objective. Methodology: We collaborate with an online retailer to procure a year of transaction data on 190,696 products that span 1,290 brands and 472,980 customers. To causally identify our results, we use a generalized difference-in-differences design with matching that exploits one policy of the firm: it discloses product availability only for the last five units. \Results: The disclosure of low product availability increases hourly sales---they grow by 13.6%---but these are more likely to be returned---product return rates increase by 17.0%. Because returns are costly, we also study net sales---product hourly sales minus hourly returns---, which increase by 12.5% after the retailer reveals low availability. The positive effects on sales and profitability amplify over wide assortments and when low availability signals are abundantly visible and disclosed for deeply discounted products whose sales season is about to end. In addition, we propose a data-driven policy that exploits these results by using machine learning to prescribe the timing of disclosure of scarcity signals in order to boost sales without spiking returns.

Porphyromonas gingivalis in the Oral Cavity of English Bulldog Newborn Puppies

Background: Periodontal disease (PD) is the most common disease of the oral cavity in cats and dogs, and it affects up to 80% of these animals. PD begins with the accumulation of bacteria on the surface of the teeth, and it poses a risk for the health of pets. Research on PD in dogs has focused on the identification and characterization of bacterial communities present in the oral cavity. Porphyromonas gingivalis is highly prevalent in the oral cavity. Therefore, the aim of this study was to detect P. gingivalis before and after dental eruption in 15 English bulldog newborn puppies, hoping to contribute to early guidance of oral hygiene management and prevent future PD.Materials, Methods & Results: Fifteen English bulldog newborn puppies were used in this study. Two groups (G1 and G2) were formed with eight and seven puppies, respectively. Oral swab samples were taken from the maxillary incisor region of animals from G1 and G2 10 days after birth (T10). At this moment, the clinical evaluation of the oral cavity showed healthy gums with a thin, shiny, pinkish, and firm margin, without any odor or granular appearance, and with no tooth eruption. On postnatal day 25 (T25), a subgingival sample was collected with a Gracey curette from the maxillary incisors; the oral cavity examination revealed healthy gums and presence of gingival sulcus. Bilateral subgingival samples were also collected from the maxillary canines and fourth premolars of the dams at T10 and T25. All newborn puppies were fed maternal breast milk and supplementation exclusively with commercial milk for dogs in individual bottles. The dams were fed commercial dry food. The average weight of G1 and G2 at T10 was 625.87 ± 85.26 g and 543.50 ± 92.88 g, respectively, and 100% (15/15) of the animals were negative for PG as assessed by polymerase chain reaction (PCR) on oral swab samples. At T25, puppies from groups G1 and G2 weighed 1.465 ± 194 g and 1.206 ± 201 g, respectively, and 100% (15/15) of the puppies were positive for P. gingivalis as assessed by PCR on subgingival samples collected with a Gracey curette. The dams of the puppies in G1 and G2 were positive for PG at T10 and T25 as determined by PCR on subgingival samples.Discussion:An important finding of this study was that the dams of the puppies in G1 and G2 were positive for P. gingivalis at T10. Several species of bacteria that cause periodontal disease can be transmitted from humans to pets; therefore, transmission from dam to puppy would be possible, but was not observed in this study at T10, when 100% (15/15) of the animals were negative for P. gingivalis. Subgingival microbiota associated with periodontitis consists essentially of Porphyromonas spp., and the presence of gingival sulcus and dental eruption are determinant factors for the presence of P. gingivalis in the oral cavity. Nevertheless, the hygiene habits of dogs, with the dam licking the puppies after dental eruption, could have been a relevant factor for transmission and appearance of P. gingivalis in the subgingival sample in 100% (15/15) of the puppies at T25. The oral microbiota is closely related to many diseases, and resident pathogenic oral bacteria can be transferred by close contact. Certain species of bacteria present in the subgingival biofilm exhibit higher etiologic relevance during the onset and progression of periodontitis, and Porphyromonas spp. is among the most important of these species. It is important to keep in mind that age is a relevant factor to prevent periodontitis. Therefore, providing owners with instructions for thorough dental brushing of animals when they still have deciduous teeth can prevent the appearance of future PD.

Did the time frame associated with the implementation of the Patient Protection and Affordable Care Act noticeably impact consumer bankruptcy filings?

Purpose The purpose of this paper is to examine whether the timing associated with the implementation of the health insurance-related provisions of the Patient Protection and Affordable Care Act (ACA) altered the presence and distribution of medical/non-medical debts accumulated by different types of bankruptcy filers. Design/methodology/approach Data were drawn from the US Bankruptcy Court’s Eastern Washington District over the years 2009, 2011 and 2014 using interval random sampling. Binary probit and Tobit analyses were used to model the existence, and distribution, of medical debts and total debts, respectively, at the time of filing. The impact of the time frame associated with the ACA was operationalized via a Chow test for structural dynamic change. Findings Chapter 13 filers in 2014 (post-ACA-based health exchange implementation) were more likely to report medical debts than Chapter 7 filers in the pre-intervention period, and were also more likely to report a larger proportion of outstanding debts owed to a single creditor. Filers claiming health insurance premium expenses in 2011 were (at the 10 percent significance level) more likely to report a more skewed distribution of medical debts. Originality/value The time frame associated with the implementation of the ACA impacts the distribution of medical debts among filers who have sufficient net disposable income to fund a Chapter 13 plan. The polarization of outstanding medical debts may indicate coverage gaps in existing health insurance policies, whose costs would be disproportionately borne by patients operating on thin financial margins.

BigBasket.Com: Redefining the Business Model

BigBasket.com, an online supermarket established in December 2011 in Bangalore, India, had become one of the major players in the Indian online grocery market by the end of March 2016.1 Run by Innovative Retail Concepts Private Limited, BigBasket.com was operating in more than 23 cities across the country in 2016. The online grocery market in India was in a stage of growth and transformation, fuelled by India's large urban population who sought a lifestyle of convenience and ease. It had also attracted many entrepreneurs who competed fiercely with each other in a market characterised by thin margins. Intense competition ensured that only a few companies were able to survive and sustain themselves. One of these companies was Big Basket, which succeeded in spite of the competition, attracting Series Da funding worth USD 150b million from the United Arab Emirates-based Abraaj Group in March 2016.2