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Recent paleobotanical investigations in Vietnam provide a good opportunity to improve our understanding of the biodiversity and paleoclimatic conditions in the geological past of Southeast Asia. Palms (Arecaceae) are a diverse family of typical thermophilous plants with a relatively low tolerance for freezing. In this study, we describe well-preserved fossil palm leaves from the Oligocene Dong Ho Formation of Hoanh Bo Basin, northern Vietnam. Characters of the fossil leaves, such as a fan-shaped costapalmate lamina, an unarmed petiole, a costa slightly enlarged at the base that then tapers distally into the blade, and well-preserved amphistomatic leaves with cuticles, suggest that they represent a new fossil species, which we herein designate

This study was designed to clarify whether Shikonin causes proliferation, apoptosis, and invasion in cholangiocarcinoma cells and to investigate the mechanism of action. QBC939 cells were cultured with different doses of Shikonin, and then 3-(4,5-dimethylthiazol-2-yl) -2,5-diphenyltetrazolium assay was used to detect cell viability. Apoptosis of cells was detected using flow cytometry with Annexin V/propidium iodide (PI) assay after being stained with Hoechst 33242. The role of Shikonin on the invasive and metastasis ability was detected using Transwell invasion assay. Real-time polymerase chain reaction and Western blotting were used to detect the expression of caspase-3, caspase-8, epidermal growth factor receptor (EGFR), and matrix metalloproteinase (MMP)-9. Shikonin inhibited proliferation and invasive ability of QBC939 cells in a dose-dependent manner; at the same time, apoptosis of cells was also observed in a concentration-dependent fashion. Moreover, Annexin V/PI assay and Transwell invasion assay results indicated that Shikonin induced apoptosis and invasion inhibitory probably due to upregulation of caspase-3 and caspase-8 expression and downregulation of MMP-9 and EGFR expression in a concentration-dependent fashion. Shikonin could enhance apoptosis and inhibit proliferation and invasion of QBC939 cells; such biological behaviors mainly occurred via upregulating the expression of caspase-3 and caspase-8 and downregulating the expression of MMP-9 and EGFR.

High performance semiconducting thin films enable the implementation of thermoelectric generators as energy harvesters for wearable applications. The optimization of material properties is critical in such applications, as restrictions introduced by the substrates on deposition temperature and active layer size, impose fundamental limitations on performance. Here we present the optimization of sputtered bismuth telluride, BiTe, and germanium telluride, GeTe, annealed at 300 ºC allowing comfortable development on polyimide substrates. The crystal structure and material composition of the films, before and after annealing, were measured by X-ray diffraction and X-ray photoelectron spectroscopy to reveal the changes in the material that enhanced the performance. The power factor of the BiTe films increased post-anneal up to 2.2 μW/cmK2, whilst the GeTe increased over 5 orders of magnitude to 7.6 μW/cmK2. A flexible thermoelectric generator was fabricated with pairs of alternating annealed BiTe and GeTe strips, reaching 7 nW per pair of output power at a temperature difference of 20 °C. Using this micro-fabrication process of thin films, compatible to roll-to-roll technologies, the physical dimensions of the generators can be tuned to deliver the required power, for providing storage energy for on-demand devices such as periodic sensing.

Recent spectral graph sparsification techniques have shown promising performance in accelerating many numerical and graph algorithms, such as iterative methods for solving large sparse matrices, spectral partitioning of undirected graphs, vectorless verification of power/thermal grids, representation learning of large graphs, etc. However, prior spectral graph sparsification methods rely on fast Laplacian matrix solvers that are usually challenging to implement in practice. This work, for the first time, introduces a solver-free approach (SF-GRASS) for spectral graph sparsification by leveraging emerging spectral graph coarsening and graph signal processing (GSP) techniques. We introduce a local spectral embedding scheme for efficiently identifying spectrally-critical edges that are key to preserving graph spectral properties, such as the first few Laplacian eigenvalues and eigenvectors. Since the key kernel functions in SF-GRASS can be efficiently implemented using sparse-matrix-vector-multiplications (SpMVs), the proposed spectral approach is simple to implement and inherently parallel friendly. Our extensive experimental results show that the proposed method can produce a hierarchy of high-quality spectral sparsifiers in nearly-linear time for a variety of real-world, large-scale graphs and circuit networks when compared with prior state-of-the-art spectral methods.

Indoleamine 2,3-dioxygenase (IDO1) plays an important role in tumor immune evasion. In this study, we investigated the changes of tumor IDO1 expression and CD8+ tumor-infiltrating lymphocytes (TILs) status in tumor microenvironment (TME) after neoadjuvant chemoradiotherapy (NCRT) or neoadjuvant chemotherapy (NCT) in esophageal squamous cell carcinoma (ESCC), respectively. Moreover, the potential predictive value of the changes of tumor IDO1 expression and CD8+TILs status on pathologic response and clinical outcome was further evaluated. By matching propensity scores in 295 patients, a total of 85 ESCC patients with neoadjuvant therapy followed by surgery were recruited, including 17 patients with NCRT and 68 patients with NCT. Tumor IDO1 expression and CD8+TILs within TME in paired specimens were evaluated by immunohistochemistry, and the changes of tumor IDO1 expression and CD8+TILs between the paired specimens were estimated. Tumor IDO1 expression significantly increased from baseline to postoperative tumor tissue after NCT (p = 0.002), whereas no significant difference was detected after NCRT (p = 0.44). The density of CD8+TILs in the tumor-invasive margin increased significantly after neoadjuvant therapy, and there was no significant difference in density changes of CD8+TILs between the NCRT and NCT groups (p = 0.118). Upregulation of tumor IDO1 expression after neoadjuvant therapy was associated with poor pathologic response (p = 0.002). Lastly, multivariate Cox analysis showed that IDO1-rise patients after neoadjuvant therapy were related to poor prognosis (p = 0.047). These results indicated that chemotherapy could promote tumor IDO1 expression, and the increased tumor IDO1 expression after neoadjuvant therapy predicted poor pathologic response and prognosis in ESCC.

Background Premenstrual syndrome (PMS) is a prevalent gynecological disease and is significantly associated with abnormal neural activity. Acupuncture is an effective treatment on PMS in clinical practice. However, few studies have been performed to investigate whether acupuncture might modulate the abnormal neural activity in patients with PMS. Thereby, the aim of the study was to assess alterations of the brain activity induced by acupuncture stimulation in PMS patients. Methods Twenty PMS patients were enrolled in this study. All patients received a 6-min resting-state functional magnetic resonance imaging (rs-fMRI) scan before and after electro-acupuncturing stimulation (EAS) at Sanyinjiao (SP6) acupoint in the late luteal phase of menstrual. Fractional amplitude of low-frequency fluctuation (fALFF) method was applied to examine the EAS-related brain changes in PMS patients. Results Compared with pre-EAS at SP6, increased fALFF value in several brain regions induced by SP6, including brainstem, right thalamus, bilateral insula, right paracentral lobule, bilateral cerebellum, meanwhile, decreased fALFF in the left cuneus, right precuneus, left inferior temporal cortex. Conclusions Our findings provide imaging evidence to support that SP6-related acupuncture stimulation may modulate the neural activity in patients with PMS. This study may partly interpret the neural mechanisms of acupuncture at SP6 which is used to treat PMS patients in clinical. Trial registration: The study was registered on http://www.chictr.org.cn. The Clinical Trial Registration Number is ChiCTR-OPC-15005918, registry in 29/01/2015.

Nicotinamide adenine dinucleotide phosphate oxidase 4 (NOX4) is a subtype of the NOX family, which is mainly expressed in the pulmonary vasculature and pulmonary endothelial cells in the respiratory system. NOX4 has unique characteristics, and is a constitutively active enzyme that primarily produces hydrogen peroxide. The signaling pathways associated with NOX4 are complicated. Negative and positive feedback play significant roles in regulating NOX4 expression. The role of NOX4 is controversial because NOX4 plays a protective or damaging role in different respiratory diseases. This review summarizes the structure, enzymatic properties, regulation, and signaling pathways of NOX4. This review then introduces the roles of NOX4 in different diseases in the respiratory system, such as acute respiratory distress syndrome, chronic obstructive pulmonary disease, and pulmonary fibrosis.

In clinical trials, the healing of wounds remains a substantial physiological and financial incumbrance on patients. Therefore, the development of new drugs that can accelerate wound healing is vital. Based on genomic methods, we identified a new peptide (RL-RL10) with the amino acid sequence 'RLFKCWKKDS' from the skin of an amphibian frog species (

For many BOT transport projects, the government imposes service level requirement on the private firm so that project capacity and stochastic demand can be better matched. We define service level as the probability of project capacity satisfying uncertain demand. The results suggest that the presence of service level requirement improves both user fee and project capacity, and also improves consumer surplus while decreases firm profit. We have made two extensions to investigate the government’s optimal service level, and to compare service level requirement with capacity regulation and price cap regulation. Some managerial insights offered by model results are discussed.

Public–private partnerships (PPPs) involve many different participants, and the equity allocation between them may influence the performance of PPP projects. While the optimal capital structure and...

In BOT road project, the government offers a firm an ex ante contract, which specifies toll price and concession period based on the forecasted demand. When the demand states are observed in the operation period, the government may request renegotiation to adapt the initial contract to the realized demand state. By considering the loss aversion behavior of the private firm, this paper shows that renegotiation takes place only if the private firm’s extent of loss aversion is sufficiently small. However, in what direction the government adjusts toll price and concession period depends on the combined effects of initial price, demand level, and demand uncertainty in each demand state. This paper has further investigated the optimal initial contract. We find that if one demand state realizes with a sufficiently large probability, then the optimal initial contract is renegotiation-proof in this demand state while inducing renegotiation in other demand states; if all demand states realize with almost equal probabilities, whether the optimal initial contract prevents or induces renegotiations in all demand states depends on the private firm’s extent of loss aversion. This paper makes two major contributions to the literature. First, we apply loss aversion to the context of renegotiation in BOT road projects and show that renegotiation is costly. Second, we consider the optimal initial contract in anticipation of ex post renegotiation and show that the government should trade off between ex ante social welfare and ex post psychological loss. To obtain more insights and to strengthen our model results, we have reexamined the optimal renegotiation and initial contracts under some relaxed assumptions.

Under the build-operate-transfer (BOT) approach, the private firm builds and operates a road within the concession period and transfers the project at no cost to the government at the end of the concession period. Based on whether the construction period and the private operation period are defined together or separately, there are two concession period structures: single-period concession structure (SPCS) and two-period concession structure (TPCS). This paper simultaneously compares socially optimal toll prices in both private and public operation periods, road quality, and concession period under SPCS and TPCS, respectively. We find that if the marginal social welfare with respect to toll price in private operation period is sufficiently more responsive than to road quality, then the optimal road capacity and toll prices under SPCS are higher than those under TPCS. Otherwise if marginal social welfare in public operation period is sufficiently more responsive to road quality, then the optimal toll prices under SPCS are lower while the optimal road quality under SPCS is higher. We also find that the optimal concession periods are independent of concession period structures. This paper has made three extensions to further investigate the effects of concession period structures (1) when the toll price is determined by the private firm; (2) when renegotiation takes place; and (3) when government support policies are present. Based on our model results, this paper derives several policy implications regarding BOT road contract design under different concession period structures.

A new species of adpressed marattialean fern with vegetative and fertile pinnules, Pectinangium xuanweiense sp. nov., is described from the Lopingian (upper Permian) in eastern Yunnan and western Guizhou provinces, Southwest China. The fronds of this new species are at least bipinnate, with linear to lanceolate ultimate pinnae. The pinnules are alternately arranged and pecopterid-type with pinnate venation. Fertile pinnules show recurved margins and abaxially bear a row of synangia on each side of the midvein. Synangia are 0.7 mm long and 0.4 mm wide on average, arranged in a density of approximately 16 per centimeter. Each synangium consists of four sporangia that are completely fused in well-regulated rectangular/ovoid shapes in the distal view. Sporangia are exannulate, 370 μm long and 200 μm wide on average. The sporangial walls are composed of at least three layers of elongated rectangular to polygonal cells. In situ spores are circular to oval, 25–(30)–35 μm in diameter, with trilete marks and microverrucate sculptures. Ultrastructural investigations indicated that the exine encompasses a perine, sexine, and nexine. In situ spores correspond to Verrucosisporites if found as sporae dispersae, and thus indicate that P. xuanweiense sp. nov. belongs to the Acitheca miltonii Group (palynological grouping) of Paleozoic marattialeans. Our study provides insight into the diversity of late Permian marattialeans in the tropics of the eastern Paleo-Tethys ocean.

Plants and insects are the two most diverse groups among terrestrial macro-organisms. They interact with each other to various extents, and constitute the most significant part of complex terrestrial ecosystems. The early Permian tuff flora in Wuda, China, buried by volcanic ash in its growth position, represents an intricate peat-forming forest in the subtropics of the eastern Tethys. However, the paleoecology of the community, especially the relationships between plants and their herbivorous insects, remains poorly understood. We report evidence for plant–insect interactions in the flora based on a thorough investigation of insect-mediated damage on the plant specimens. In total, 8 types of insect-mediated damage, belonging to 5 functional feeding groups, were recognized in 11 plant species. The insect damage recognized in the flora comprises oviposition on calamitalean axes; external leaf feeding, galling, oviposition, and wood boring on marattialean ferns; external leaf feeding, galling, and oviposition on noeggerathialeans; external leaf feeding, piercing and sucking, galling, and oviposition on cycadophytes. Damage occurrence indicates that the cycadophyte taxon Pterophyllum sp. cf. P. daihoense is likely the most frequently targeted plant in the flora. Our results may be a subset of the broader pattern of plant–insect interaction in the early Permian subtropics, due to the unusual environmental conditions, but they do provide a glimpse into the peat-forming swamp ecosystems of the late Paleozoic Cathaysia.

The Lopingian (upper Permian) in Southwest China yields diverse marattialean plants; however, most of these have been recorded as isolated fragments of fronds, pinnules, and stems. Marattialean Qasimia specimens were recently collected from the upper Permian Xuanwei Formation of Yunnan Province, Southwest China. The well-preserved synangia, sporangia, and prominent in situ spores permitted the emendation of the genus Qasimia and the establishment of the species Q. yunnanica sp. nov. This plant possesses alternately or sub-oppositely arranged fertile pinnules with abaxially attached synangia. The synangia are sessile and bivalvate, with a length nearly half the width of the pinnules. A synangium valve consists of approximately 20 long ellipsoids and laterally fused sporangia. In situ spores of the Punctatosporites type are monolete, 97 × 74 μm on average, with a microverrucate/microgranulate to vermiculate sculpture; these represent the largest in situ spores of this type. The sporangial wall has at least two layers of polygonal/elongated cells. The exine comprises a perine, sexine, and nexine. The characteristics of the marattialeans with bilaterally symmetrical synangia were analyzed based on a comparison of eight related genera in the late Paleozoic and Marattia after the late Paleozoic. The Qasimia-type synangium represents the earliest occurrence of bivalvate synangium, which is a typical feature of modern marattialeans. Although the origin of the bilaterally symmetrical marattialean synangia remains elusive, marattialeans with this type of synangia first appeared in the Euramerica during the late Carboniferous and then migrated to the Cathaysia, where they became more prosperous until the late Permian.

A new permineralized stem, Protophyllocladoxylon yiwuense Gou et Feng sp. nov., is described from the Middle Jurassic Xishanyao Formation in Naomaohu Town of Yiwu County, Hami City, Xinjiang Uygur Autonomous Region, Northwest China. The stem is only preserved with secondary xylem, which is pycnoxylic and exclusively composed of tracheids and parenchymatous rays. The tracheids have uniseriate or biseriate, alternately arranged bordered pits on their radial walls, and uniseriate bordered pits on the tangential walls. The rays are uniseriate or partially biseriate, up to 34 cells high. There are one or two large, simple pits in each cross field. A branch trace horizontally passes through the secondary xylem showing anatomical structures identical to the secondary xylem. Analyses of the growth-ring width and mean sensitivity values indicate that P. yiwuense had long growing seasons with readily available water supplies and favorable paleoclimatic conditions. White-rot decay features are commonly recognized in the stem, including pocket-like cavities, complete removal of the middle lamellae, thickened corners and separation of the secondary walls of tracheids, as well as septa-like structures in the tracheid lumens due to the cell's reactions to fungal activity. Our study sheds new light into the plant diversity and paleoenvironmental and paleoecological conditions of the Middle Jurassic.

Fossil wood serves as a natural data source for deciphering plant physiological features and paleoclimatic and paleoenvironmental conditions experienced during its lifespan. Although permineralized conifer wood commonly occurs in the Jurassic of Xinjiang Uygur Autonomous Region (Xinjiang), Northwest China, their physiological features and paleoclimatic and paleoenvironmental significance have been rarely studied. Here, we quantitatively analyzed the anatomical characteristics of a permineralized conifer stem (Agathoxylon sp.) from the Middle Jurassic Xishanyao Formation in Naomaohu Town of Yiwu County, Hami City, Xinjiang. The fossil stem is only preserved with secondary xylem. The secondary xylem is pycnoxylic and exclusively composed of tracheids and parenchymatous rays. Tracheids have mostly uniseriate or biseriate, partially triseriate or tetraseriate, alternately or sub-oppositely arranged bordered pits on their radial walls. Rays are mostly uniseriate, partially biseriate, and are up to 27 cells high. There are 4 to 11 cupressoid pits in each cross field, arranged in the araucarioid type. Growth rings are distinct and wide. The mean sensitivity and ring markedness index analyses of growth rings suggest that a stable paleoclimate with regular seasonal fructifications could have prevailed in the Santanghu Basin during the Middle Jurassic. Statistical analyses of cell diameters in 11 successive growth rings indicate that this fossil plant was deciduous. Our study sheds new light on leaf phenology and paleoclimatic and paleoenvironmental conditions of Middle Jurassic conifer plants.

Beetles are the most diverse group of macroscopic organisms since the mid-Mesozoic. Much of beetle speciosity is attributable to myriad life habits, particularly diverse-feeding strategies involving interactions with plant substrates, such as wood. However, the life habits and early evolution of wood-boring beetles remain shrouded in mystery from a limited fossil record. Here we report new material from the upper Permian (Changhsingian Stage, ca. 254–252 million-years ago) of China documenting a microcosm of ecological associations involving a polyphagan wood-borer consuming cambial and wood tissues of the conifer Ningxiaites specialis. This earliest evidence for a component community of several trophically interacting taxa is frozen in time by exceptional preservation. The combination of an entry tunnel through bark, a cambium mother gallery, and up to 11 eggs placed in lateral niches—from which emerge multi-instar larval tunnels that consume cambium, wood and bark—is ecologically convergent with Early Cretaceous bark-beetle borings 120 million-years later., Numerous gaps remain in our knowledge of how groups of organisms interacted in ancient ecosystems. Here, Feng and colleagues describe a late Permian fossil wood-boring beetle microcosm, with the oldest known example of complex tunnel geometry, host tissue response, and the presence of fungi within.

Bark is an important functional structure in woody plants. However, fossil tree axes are commonly decorticated. The development of bark during the evolutionary history of fossil plants thus remains poorly understood. Here, we describe exceptionally well-preserved extraxylary tissues of the Lopingian (Late Permian) conifer Ningxiaites specialis Feng, including vascular cambium and bark, from the Sunjiagou Formation (Changhsingian) of northern China. The vascular cambium bears one or two layers of cambial cells. The bark comprises secondary phloem and periderm. The secondary phloem consists of rays, axial parenchyma and sieve cells. The rays of the secondary phloem are uniseriate and continuous from the rays of the xylem. They are more frequently present in the inner zone of the secondary phloem. Axial parenchyma cells are vertically aligned and appear more regularly distributed in the outer zone of the secondary phloem. Elliptical or subcircular sieve areas are placed on the radial walls of the sieve cells. The periderm located outside the secondary phloem is composed of imbricate flattened cork cells. The cork cells show suberised cell walls and are generally filled with dark contents. Remains of the secondary phloem present between layers of periderm indicate the formation of rhytidome-type bark. This is the first detailed report of the bark anatomy of a conifer from the upper Palaeozoic of Cathaysia, and shed light on the early diversity of bark structure during the evolutionary history of conifers.

The terrestrial Permian-Triassic transitional section at Chahe in western Guizhou Province, South China has served as a key reference section for the study of terrestrial PTB, as well as the end-Permian mass extinction on land in South China. However, Bourquin et al. (2018) recently reported that the PTB interval at Chahe has undergone serious tectonic deformation and thus is not suitable for studying the PTB transition or the terrestrial end-Permian extinction due to an unknown amount of stratigraphy removed/displaced by faulting. In order to clarify the observations of Bourquin et al. (2018), we re-surveyed the Chahe section in further detail recently and our observations suggest that the interpreted deformation by Bourquin et al. (2018) cannot be verified and it also contradicts the regional litho- and bio-stratigraphic and chemostratigraphic results. We provide detailed outcrop imagery and data for all colleagues who are interested in this section to check our observations.

Spectral graph sparsification aims to find ultra-sparse subgraphs whose Laplacian matrix can well approximate the original Laplacian eigenvalues and eigenvectors. In recent years, spectral sparsification techniques have been extensively studied for accelerating various numerical and graph-related applications. Prior nearly-linear-time spectral sparsification methods first extract low-stretch spanning tree from the original graph to form the backbone of the sparsifier, and then recover small portions of spectrally-critical off-tree edges to the spanning tree to significantly improve the approximation quality. However, it is not clear how many off-tree edges should be recovered for achieving a desired spectral similarity level within the sparsifier. Motivated by recent graph signal processing techniques, this paper proposes a similarity-aware spectral graph sparsification framework that leverages efficient spectral off-tree edge embedding and filtering schemes to construct spectral sparsifiers with guaranteed spectral similarity (relative condition number) level. An iterative graph densification scheme is also introduced to facilitate efficient and effective filtering of off-tree edges for highly ill-conditioned problems. The proposed method has been validated using various kinds of graphs obtained from public domain sparse matrix collections relevant to VLSI CAD, finite element analysis, as well as social and data networks frequently studied in many machine learning and data mining applications. For instance, a sparse SDD matrix with 40 million unknowns and 180 million nonzeros can be solved (1E-3 accuracy level) within two minutes using a single CPU core and about 6GB memory., 14 pages, 13 figures. arXiv admin note: substantial text overlap with arXiv:1711.05135

This paper proposes a scalable algorithmic framework for effective-resistance preserving spectral reduction of large undirected graphs. The proposed method allows computing much smaller graphs while preserving the key spectral (structural) properties of the original graph. Our framework is built upon the following three key components: a spectrum-preserving node aggregation and reduction scheme, a spectral graph sparsification framework with iterative edge weight scaling, as well as effective-resistance preserving post-scaling and iterative solution refinement schemes. By leveraging recent similarity-aware spectral sparsification method and graph-theoretic algebraic multigrid (AMG) Laplacian solver, a novel constrained stochastic gradient descent (SGD) optimization approach has been proposed for achieving truly scalable performance (nearly-linear complexity) for spectral graph reduction. We show that the resultant spectrally-reduced graphs can robustly preserve the first few nontrivial eigenvalues and eigenvectors of the original graph Laplacian and thus allow for developing highly-scalable spectral graph partitioning and circuit simulation algorithms.ACM Reference Format:Zhiqiang Zhao and Zhuo Feng. 2019. Effective-Resistance Preserving Spectral Reduction of Graphs. In The 56th Annual Design Automation Conference 2019 (DAC '19), June 2–6, 2019, Las Vegas, NV, USA. ACM, New York, NY, USA, 6 pages. https://doi.org/10.1145/3316781.3317809

Flexible thermoelectric generators (TEGs) can provide uninterrupted, green energy from body-heat, overcoming bulky battery configurations that limit the wearable-technologies market today. High-throughput production of flexible TEGs is currently dominated by printing techniques, limiting material choices and performance. This work investigates the compatibility of physical vapour deposition (PVD) techniques with a flexible commercial process, roll-to-roll (R2R), for thermoelectric applications. We demonstrate, on a flexible polyimide substrate, a sputtered Bi2Te3/GeTe TEG with Seebeck coefficient (S) of 140 μV/K per pair and output power (P) of 0.4 nW per pair for a 20 °C temperature difference. For the first time, thermoelectric properties of R2R sputtered Bi2Te3 films are reported and we demonstrate the ability to tune the power factor by lowering run times, lending itself to a high-speed low-cost process. To further illustrate this high-rate PVD/R2R compatibility, we fabricate a TEG using Virtual Cathode Deposition (VCD), a novel high deposition rate PVD tool, for the first time. This Bi2Te3/Bi0.5Sb1.5Te3 TEG exhibits S = 250 μV/K per pair and P = 0.2 nW per pair for a 20 °C temperature difference.

Public-private partnership (PPP) is a form of government procurement where a private entity (firm) provides upfront funding to construct a major public infrastructure project. After the project is completed, the firm collects payments from end consumers who use the project to recoup the construction cost and generate a profit. Due to the enormous expense of infrastructure projects, the government and the firm often entertain intense negotiations on the subject of the construction and compensation details. However, existing literature has not studied the impact of negotiations on the outcome of the final PPP agreement. We solve for the Nash bargaining outcome between the government and the firm under PPP, and compare it to the traditional procurement where the government provides upfront funding for the project from its operating budget. The firm wants to maximize profit while the goal of the government is to maximize social welfare which typically includes consumer surplus and public revenue. We find that when public revenue accounts for a large proportion of the government's objective function, PPP can lead to a win-win situation for the government and the firm, compared to traditional procurement. In contrast, when the government's goal is to mainly maximize consumer surplus, PPP can result in a lose-lose outcome. However, in this case, the government can utilize subsidies (provided to either the firm or the end consumers) to attain a desired bargaining outcome under PPP. Our results are useful for informing policy makers of instances when PPP is better than traditional procurement and when government subsidies should be provided.

A growing number of governments are persuading private firms to build and operate infrastructure projects for them. Since the initial contract between the government and firm is based on forecasted demand, the government can renegotiate to adjust it after demand is realized. We use stylized modelling to study whether the government should offer the firm a flexible contract that allows ex post renegotiation or a rigid contract when the private firm is loss-averse. Our model results show that the government’s decision depends on two key factors: demand uncertainty and the firm’s loss aversion. We further investigate whether the government should renegotiate the subsidy or concession period. We find that such a decision depends on the improvement in social welfare after the project transfer. To offer operational insights into the mitigation of the social welfare loss by promoting renegotiation, we discuss three strategies that the government can use: imposing a tax rate, running a competing domestic project, and offering a dollar-based subsidy. We describe the conditions under which these three strategies are conducive to renegotiation as well as their effects on the initial contract.

A new permineralized stem, Ductoagathoxylon wangii Gou et Feng, is described from the Middle Jurassic Xishanyao Formation in Naomaohu Town of Yiwu County, Hami City, Xinjiang Uygur Autonomous Region, Northwest China. The fossil stem is preserved with pith, primary xylem, and secondary xylem. The solid pith is heterocellular, and characterized by the presence of regularly arranged clusters of secretory cells at the periphery. The primary xylem is endarch to mesarch, showing annular, helical, and scalariform thickenings on the tracheid walls from the protoxylem to the metaxylem. The secondary xylem is pycnoxylic and exclusively composed of tracheids and parenchymatous rays. The secondary xylem tracheids have mostly uniseriate, partially biseriate, and rarely triseriate alternately arranged contiguous bordered pits on their radial walls. The rays are uniseriate and up to ten cells high. There are five to nine cupressoid pits in each cross-field, arranged in the araucarioid type. Growth rings are distinct and are characterized by a narrow band of latewood. This is the third fossil stem described from the Middle Jurassic of China that is preserved with anatomical structures of pith, primary, and secondary xylem, thus shedding new light on the diversity and evolution of conifers. The occurrence of a traumatic scar in the stem indicates that the tree was probably damaged by an abiotic cause, but it successfully survived through physiological responses to the wound.

Despite extensive efforts to develop efficacious therapeutic approaches, the treatment of skin wounds remains a considerable clinical challenge. Existing remedies cannot sufficiently meet current needs, so the discovery of novel pro-healing agents is of growing importance. In the current research, we identified a novel short peptide (named RL-QN15, primary sequence 'QNSYADLWCQFHYMC') from Rana limnocharis skin secretions, which accelerated wound healing in mice. Exploration of the underlying mechanisms showed that RL-QN15 activated the MAPK and Smad signaling pathways, and selectively modulated the secretion of cytokines from macrophages. This resulted in the proliferation and migration of skin cells and dynamic regulation of TGF-β1 and TGF-β3 in wounds, which accelerated re-epithelialization and granulation tissue formation and thus skin regeneration. Moreover, RL-QN15 showed significant therapeutic potency against chronic wounds, skin fibrosis, and oral ulcers. Our results highlight frog skin secretions as a potential treasure trove of bioactive peptides with healing activity. The novel peptide (RL-QN15) identified in this research shows considerable capacity as a candidate for the development of novel pro-healing agents.