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1.
PLoS Comput Biol ; 20(5): e1012049, 2024 May.
Artigo em Inglês | MEDLINE | ID: mdl-38739654

RESUMO

How natural communities maintain their remarkable biodiversity and which species survive in complex communities are central questions in ecology. Resource competition models successfully explain many phenomena but typically predict only as many species as resources can coexist. Here, we demonstrate that sequential resource utilization, or diauxie, with periodic growth cycles can support many more species than resources. We explore how communities modify their own environments by sequentially depleting resources to form sequences of temporal niches, or intermediately depleted environments. Biodiversity is enhanced when community-driven or environmental fluctuations modulate the resource depletion order and produce different temporal niches on each growth cycle. Community-driven fluctuations under constant environmental conditions are rare, but exploring them illuminates the temporal niche structure that emerges from sequential resource utilization. With environmental fluctuations, we find most communities have more stably coexisting species than resources with survivors accurately predicted by the same temporal niche structure and each following a distinct optimal strategy. Our results thus present a new niche-based approach to understanding highly diverse fluctuating communities.


Assuntos
Biodiversidade , Ecossistema , Modelos Biológicos , Biologia Computacional , Animais
2.
Radiat Oncol J ; 42(1): 43-49, 2024 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-38549383

RESUMO

PURPOSE: This retrospective study aimed to compare clinical outcomes and dosimetric parameters between radiation therapy (RT) techniques in patients with thymic epithelial tumor (TET). MATERIALS AND METHODS: From January 2016 to December 2020, 101 patients with TET received adjuvant RT (median, 52.8 Gy; range, 48.4 to 66.0). Three different RT techniques were compared: three-dimensional conformal RT (3D-CRT; n = 59, 58.4%), intensity-modulated RT (IMRT; n = 23, 22.8%), and proton beam therapy (PBT; n = 19, 18.8%). RESULTS: The median age of the patients and the follow-up period were 55 years (range, 28 to 79) and 43.4 months (range, 7.7 to 77.2). Patients in the PBT group were of the youngest age (mean age, 45.4 years), while those in IMRT group had the largest clinical target volume (mean volume, 149.6 mL). Patients in the PBT group had a lower mean lung dose (4.4 Gy vs. 7.6 Gy vs. 10.9 Gy, respectively; p < 0.001), lower mean heart dose (5.4 Gy vs. 10.0 Gy vs. 13.1 Gy, respectively; p = 0.003), and lower mean esophageal dose than patients in the 3D-CRT and IMRT groups (6.3 Gy vs. 9.8 Gy vs. 13.5 Gy, respectively; p = 0.011). Twenty patients (19.8%) showed disease recurrence, and seven patients (6.9%) died. The differences in the survival rates between RT groups were not statistically significant. CONCLUSION: In patients with TET who underwent adjuvant RT, PBT resulted in a lower dose of exposure to adjacent organs at risk. Survival outcomes for patients in PBT group were not significantly different from those in other groups.

3.
Sci Rep ; 14(1): 2032, 2024 01 23.
Artigo em Inglês | MEDLINE | ID: mdl-38263232

RESUMO

Polyps are well-known cancer precursors identified by colonoscopy. However, variability in their size, appearance, and location makes the detection of polyps challenging. Moreover, colonoscopy surveillance and removal of polyps are highly operator-dependent procedures and occur in a highly complex organ topology. There exists a high missed detection rate and incomplete removal of colonic polyps. To assist in clinical procedures and reduce missed rates, automated methods for detecting and segmenting polyps using machine learning have been achieved in past years. However, the major drawback in most of these methods is their ability to generalise to out-of-sample unseen datasets from different centres, populations, modalities, and acquisition systems. To test this hypothesis rigorously, we, together with expert gastroenterologists, curated a multi-centre and multi-population dataset acquired from six different colonoscopy systems and challenged the computational expert teams to develop robust automated detection and segmentation methods in a crowd-sourcing Endoscopic computer vision challenge. This work put forward rigorous generalisability tests and assesses the usability of devised deep learning methods in dynamic and actual clinical colonoscopy procedures. We analyse the results of four top performing teams for the detection task and five top performing teams for the segmentation task. Our analyses demonstrate that the top-ranking teams concentrated mainly on accuracy over the real-time performance required for clinical applicability. We further dissect the devised methods and provide an experiment-based hypothesis that reveals the need for improved generalisability to tackle diversity present in multi-centre datasets and routine clinical procedures.


Assuntos
Crowdsourcing , Aprendizado Profundo , Pólipos , Humanos , Colonoscopia , Computadores
4.
Sci Rep ; 13(1): 21672, 2023 12 07.
Artigo em Inglês | MEDLINE | ID: mdl-38066203

RESUMO

In this study, we propose an optimal method for monitoring the key electrophysiological sign, the Lateral Spread Response (LSR), during microvascular decompression (MVD) surgery for hemifacial spasm (HFS). Current monitoring methods and interpretations of LSR remain unclear, leading to potential misinterpretations and undesirable outcomes." We prospectively collected data from patients undergoing MVD for HFS, including basic demographics, clinical characteristics, and surgical outcomes. Stimulation intensity was escalated by 1 mA increments to identify the optimal range for effective LSR. We designated the threshold at which we can observe LSR as THR1 and THR2 for when LSR disappears, with high-intensity stimulation (30 mA) designated as THR30. Subsequently, we compared abnormal muscle responses (AMR) between the optimal range (between THR1 and THR2) and THR30. Additionally, we conducted an analysis to identify and assess factors associated with artifacts and their potential impact on clinical outcomes. As stimulation intensity increases, the onset latency to detect AMR was shortened. The first finding of the study was high intensity stimulation caused artifact that mimic the wave of LSR. Those artifacts were observed even after decompression thus interfere interpretation of disappearance of LSR. Analyzing the factors related to the artifact, we found the AMR detected at onset latency below 9.6 ms would be the lateral spreading artifact (LSA) rather than true LSR. To avoid false positive LSR from LSA, we should stepwise increase stimulation intensity and not to surpass the intensity that cause LSR onset latency below 10 ms.


Assuntos
Espasmo Hemifacial , Cirurgia de Descompressão Microvascular , Humanos , Espasmo Hemifacial/cirurgia , Cirurgia de Descompressão Microvascular/métodos , Resultado do Tratamento , Monitorização Intraoperatória/métodos , Músculos Faciais , Estudos Retrospectivos
5.
bioRxiv ; 2023 Oct 24.
Artigo em Inglês | MEDLINE | ID: mdl-37961366

RESUMO

In microbial communities, various cell types often coexist by occupying distinct spatial domains. What determines the shape of the interface between such domains-which in turn influences the interactions between cells and overall community function? Here, we address this question by developing a continuum model of a 2D spatially-structured microbial community with two distinct cell types. We find that, depending on the balance of the different cell proliferation rates and substrate friction coefficients, the interface between domains is either stable and smooth, or unstable and develops finger-like protrusions. We establish quantitative principles describing when these different interfacial behaviors arise, and find good agreement both with the results of previous experimental reports as well as new experiments performed here. Our work thus helps to provide a biophysical basis for understanding the interfacial morphodynamics of proliferating microbial communities, as well as a broader range of proliferating active systems.

6.
Phys Rev E ; 108(3): L032301, 2023 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-37849094

RESUMO

In growing populations, the fate of mutations depends on their competitive ability against the ancestor and their ability to colonize new territory. Here we present a theory that integrates both aspects of mutant fitness by coupling the classic description of one-dimensional competition (Fisher equation) to the minimal model of front shape (Kardar-Parisi-Zhang equation). We solve these equations and find three regimes, which are controlled solely by the expansion rates, solely by the competitive abilities, or by both. Collectively, our results provide a simple framework to study spatial competition.


Assuntos
Aptidão Genética , Genética Populacional , Mutação
7.
Life (Basel) ; 13(10)2023 Oct 07.
Artigo em Inglês | MEDLINE | ID: mdl-37895403

RESUMO

(1) Background: In cases of hemifacial spasm (HFS), there are various patterns related to the vascular compression of the facial nerve, including a very rare form that is seen when the offending vessel penetrates the facial nerve. However, there have been few reports in the literature regarding the associated surgical techniques and postoperative prognosis. (2) Methods: A retrospective review was conducted of 4755 patients who underwent microvascular decompression (MVD) surgery from April 1997 to June 2023. In total, 8 out of the 4755 patients (0.2%) exhibited a penetrating offending vessel; the medical and surgical records of these 8 patients were then analyzed. Surgery was then attempted to maximally decompress the penetrating offender. (3) Results: Seven out of the eight patients (87.5%) were spasm-free immediately after surgery, and one had only 10% residual spasm compared to their preoperative condition. That patient was also spasm-free one year later. Postoperative facial palsy occurred in one patient (12.5%) who was assessed as grade II in the House-Brackmann grading system. In another patient, the resection of a small facial nerve bundle did not result in facial palsy. There were no cases of hearing loss or other complications. (4) Conclusions: Decompressing the penetrating offender did not increase the incidence of facial palsy, and the prognosis for hemifacial spasms was good. Therefore, when a penetrating pattern was encountered during MVD surgery, decompression between the penetrating offender and the facial nerve may offer good results.

8.
Life (Basel) ; 13(10)2023 Oct 16.
Artigo em Inglês | MEDLINE | ID: mdl-37895445

RESUMO

The purpose of this study was to investigate the outcome of microvascular decompression (MVD) in patients with hemifacial spasm (HFS) who have no definite radiological neurovascular compression (NVC). Sixteen HFS patients without radiological NVC on preoperative MRI underwent MVD surgery. The symptoms were left-sided in fourteen (87.5%) and right-sided in two patients (12.5%). Intraoperatively, the most common vessel compressing the facial nerve was the AICA (8, 44.4%), followed by arterioles (5, 27.8%), veins (4, 22.2%), and the PICA (1, 5.6%). The most common compression site was the cisternal portion (13, 76.5%) of the facial nerve, followed by the REZ (4, 23.5%). One patient (6.3%) was found to have multiple NVC sites. Arachnoid type (7, 50%) was the most common compressive pattern, followed by perforator type (4, 28.6%), sandwich type (2, 14.3%), and loop type (1, 7.1%). A pure venous compression was seen in two patients, while a combined venous-arterial "sandwich" compression was detected in two patients. Symptom improvement was observed in all of the patients. Only one patient experienced recurrence after improvement. Based on our experience, MVD surgery can be effective for primary HFS patients with no definite radiological NVC. MVD can be considered if the patient shows typical HFS features, although NVC is not evident on MRI.

9.
Life (Basel) ; 13(8)2023 Aug 18.
Artigo em Inglês | MEDLINE | ID: mdl-37629628

RESUMO

(1) Background: Cerebrospinal fluid (CSF) leakage is one of the most common complications of microvascular decompression (MVD) surgery. Before fatal complications, such as intracranial infection, occur, early recognition and prompt treatment are essential. (2) Methods: The clinical data of 475 patients who underwent MVD surgery from September 2020 to March 2023 were retrospectively analyzed. In these patients, if there were any symptoms of CSF leakage, and if CSF leakage was evident, a lumbar drainage catheter was inserted immediately. (3) Results: CSF leakage was suspected in 18 (3.8%) patients. Five of these patients (1.1%) showed signs of CSF leakage during conservative management and subsequently underwent catheter insertion for lumbar drainage. The lumbar drain was removed after an average of 5.2 days, resulting in an average hospitalization of 14.8 days. In all 5 patients, CSF leakage was resolved without reoperation. (4) Conclusions: Our treatment strategy prevented the development of fatal complications. Close observation of the symptoms and postoperative temporal bone computed tomography and audiometry are considered to be good evaluation methods for all patients. If CSF leakage is certain, it is important to perform lumbar drainage immediately.

10.
Proc Natl Acad Sci U S A ; 120(35): e2212113120, 2023 08 29.
Artigo em Inglês | MEDLINE | ID: mdl-37603734

RESUMO

Predicting the composition and diversity of communities is a central goal in ecology. While community assembly is considered hard to predict, laboratory microcosms often follow a simple assembly rule based on the outcome of pairwise competitions. This assembly rule predicts that a species that is excluded by another species in pairwise competition cannot survive in a multispecies community with that species. Despite the empirical success of this bottom-up prediction, its mechanistic origin has remained elusive. In this study, we elucidate how this simple pattern in community assembly can emerge from resource competition. Our geometric analysis of a consumer-resource model shows that trio community assembly is always predictable from pairwise outcomes when one species grows faster than another species on every resource. We also identify all possible trio assembly outcomes under three resources and find that only two outcomes violate the assembly rule. Simulations demonstrate that pairwise competitions accurately predict trio assembly with up to 100 resources and the assembly of larger communities containing up to twelve species. We then further demonstrate accurate quantitative prediction of community composition using the harmonic mean of pairwise fractions. Finally, we show that cross-feeding between species does not decrease assembly rule prediction accuracy. Our findings highlight that simple community assembly can emerge even in ecosystems with complex underlying dynamics.


Assuntos
Ecologia , Microbiota , Laboratórios
11.
Sci Rep ; 13(1): 4676, 2023 Mar 22.
Artigo em Inglês | MEDLINE | ID: mdl-36949218

RESUMO

The DAMA/LIBRA collaboration has reported the observation of an annual modulation in the event rate that has been attributed to dark matter interactions over the last two decades. However, even though tremendous efforts to detect similar dark matter interactions were pursued, no definitive evidence has been observed to corroborate the DAMA/LIBRA signal. Many studies assuming various dark matter models have attempted to reconcile DAMA/LIBRA's modulation signals and null results from other experiments, however no clear conclusion can be drawn. Apart from the dark matter hypothesis, several studies have examined the possibility that the modulation is induced by variations in detector's environment or their specific analysis methods. In particular, a recent study presents a possible cause of the annual modulation from an analysis method adopted by the DAMA/LIBRA experiment in which the observed annual modulation could be reproduced by a slowly varying time-dependent background. Here, we study the COSINE-100 data using an analysis method similar to the one adopted by the DAMA/LIBRA experiment and observe a significant annual modulation, however the modulation phase is almost opposite to that of the DAMA/LIBRA data. Assuming the same background composition for COSINE-100 and DAMA/LIBRA, simulated experiments for the DAMA/LIBRA without dark matter signals also provide significant annual modulation with an amplitude similar to DAMA/LIBRA with opposite phase. Even though this observation does not directly explain the DAMA/LIBRA results directly, this interesting phenomenon motivates more profound studies of the time-dependent DAMA/LIBRA background data.

12.
Sensors (Basel) ; 23(3)2023 Jan 25.
Artigo em Inglês | MEDLINE | ID: mdl-36772385

RESUMO

Spectral congestion and modern consumer applications motivate radio technologies that efficiently cooperate with nearby users and provide several services simultaneously. We designed and implemented a joint positioning-communications system that simultaneously enables network communications, timing synchronization, and localization to a variety of airborne and ground-based platforms. This Communications and High-Precision Positioning (CHP2) system simultaneously performs communications and precise ranging (<10 cm) with a narrow band waveform (10 MHz) at a carrier frequency of 915 MHz (US ISM) or 783 MHz (EU Licensed). The ranging capability may be extended to estimate the relative position and orientation by leveraging the spatial diversity of the multiple-input, multiple-output (MIMO) platforms. CHP2 also digitally synchronizes distributed platforms with sub-nanosecond precision without support from external systems (GNSS, GPS, etc.). This performance is enabled by leveraging precise time-of-arrival (ToA) estimation techniques, a network synchronization algorithm, and the intrinsic cooperation in the joint processing chain that executes these tasks simultaneously. In this manuscript, we describe the CHP2 system architecture, hardware implementation, and in-lab and over-the-air experimental validation.

13.
Diagnostics (Basel) ; 13(3)2023 Jan 27.
Artigo em Inglês | MEDLINE | ID: mdl-36766574

RESUMO

Although bowel preparation influences small bowel visibility for small bowel capsule endoscopy (SBCE), the optimal timing for bowel preparation has not been established yet. Thus, the aim of the study was to evaluate the optimal timing of polyethylene glycol (PEG) for small bowel preparation before SBCE. This multicenter prospective observational study was conducted on patients who underwent SBCE following bowel preparation with polyethylene glycol (PEG). Patients were categorized into three groups according to the time used for completing PEG ingestion: group A, within 6 h; group B, 6-12 h; and group C, over 12 h. The percentage of unclean segment in small bowel (unclean image duration / small bowel transit time × 100) and small bowel visibility quality (SBVQ) were evaluated according to the time interval between the last ingestion of PEG and swallowing of small bowel capsule endoscope. A total of 90 patients were enrolled and categorized into group A (n = 40), group B (n = 27), and group C (n = 23). The percentage of unclean segment in the entire small bowel increased gradually from group A to C (6.6 ± 7.6% in group A, 11.3 ± 11.8% in group B, and 16.2 ± 10.7% in group C, p = 0.001), especially in the distal small bowel (11.4 ± 13.6% in group A, 20.7 ± 18.7% in group B, and 29.5 ± 16.4% in group C, p < 0.001). The proportion of patients with adequate SBVQ in group A was significantly (p < 0.001) higher (30/40, 75.0%) than that in group B (17/27, 63.0%) or group C (5/23, 21.7%). In multivariate analysis, group A was associated with an increased likelihood of adequate SBVQ compared with group C (odds ratio [OR]: 13.05; 95% confidence interval [CI]: 3.53-48.30, p < 0.001). Completing PEG ingestion within 6 h prior to SBCE could enhance small bowel visibility.

14.
ArXiv ; 2023 Jan 18.
Artigo em Inglês | MEDLINE | ID: mdl-36713251

RESUMO

In growing populations, the fate of mutations depends on their competitive ability against the ancestor and their ability to colonize new territory. Here we present a theory that integrates both aspects of mutant fitness by coupling the classic description of one-dimensional competition (Fisher equation) to the minimal model of front shape (KPZ equation). We solved these equations and found three regimes, which are controlled solely by the expansion rates, solely by the competitive abilities, or by both. Collectively, our results provide a simple framework to study spatial competition.

15.
Healthcare (Basel) ; 10(12)2022 Dec 06.
Artigo em Inglês | MEDLINE | ID: mdl-36553986

RESUMO

This study aimed to investigate the long-term effects of and satisfaction with integrative Korean medicine treatment and motion style acupuncture treatment (MSAT) in patients with lumbar disc herniation (LDH). We retrospectively analyzed medical charts and prospectively surveyed adult patients aged between 19 and 64 years treated for lumbar disc herniation for at least 6 days at three Korean hospitals from 1 January 2015 to 31 December 2020. The primary outcome was the Numeric Rating Scale (NRS) for back pain. Secondary outcome measures included the NRS for radiating leg pain, the Oswestry Disability Index (ODI), and the European Quality of Life-5 Dimension-5 Level (EQ-5D-5L) questionnaire. The NRS scores for low back pain decreased from 5.40 ± 1.58 to 2.92 ± 2.09, NRS for radiating leg pain from 5.57 ± 1.56 to 1.78 ± 2.36, and ODI from 46.39 ± 16.72 to 16.47 ± 15.61 at baseline and survey, respectively. The EQ-5D-5L increased from 0.57 ± 0.19 to 0.82 ± 0.14. In conclusion, Korean medicine and MSAT could be effective treatment methods for patients with LDH. The results of this study can be used as helpful information for clinicians who treat patients with LDH in real clinical settings.

16.
Materials (Basel) ; 15(18)2022 Sep 08.
Artigo em Inglês | MEDLINE | ID: mdl-36143565

RESUMO

Research interest is active in Eu2+/Dy3-doped SrAl2O4 phosphors, and the photocurrent characteristics of Eu2+-doped SrAl2O4 without Dy3+ was investigated extensively. However, it exhibits a low photocurrent of ~1 µA owing to high resistance. In this study, the changes in a photo-induced current with grain size were examined. The effect of the processing methods on the microstructure and photocurrent characteristics of Eu2+-doped SrAl2O4 phosphors was investigated. (Sr0.99Eu0.01)Al2O4 powders were synthesized using a conventional solid-state method and calcined at 1350 °C under a 3% H2/(Ar + H2) reducing gas atmosphere. Sample pellets were fabricated as conventional and hot-press-sintered bodies at 1400 °C. A thin film of the sample was deposited on an alumina substrate by radio-frequency magnetron sputtering. Scanning electron microscopy revealed that the hot-press-sintered body has larger grains than the conventionally sintered body. The photo-induced current of the hot-press-sintered body at 400 lx was ~100 and ~1000 times higher than those of the conventionally sintered body and thin film, respectively. Impedance analysis confirmed that this dramatic increase in the photo-induced current is closely related to the increase in the grain size and crystallinity of the sample. This study verifies the applicability of Eu2+-doped SrAl2O4 as both a phosphor and photosensor.

17.
Medicine (Baltimore) ; 101(30): e29311, 2022 Jul 29.
Artigo em Inglês | MEDLINE | ID: mdl-35905267

RESUMO

During endoscopic orthopedic surgery, epinephrine mixed with irrigation saline is frequently used to improve visualization. By monitoring hemodynamic parameters throughout the procedure, we intended to discover the hemodynamic effect of epinephrine between the normal saline irrigation fluid without epinephrine group (NS) and normal saline irrigation fluid with epinephrine group (EPI). Patients who underwent 1-level lumbar decompression or discectomy surgery without fusion between August 2019 and July 2020 were reviewed retrospectively. The hemodynamic parameters were compared between the NS group and EPI group. As a second endpoint, the incidence of hypotension and hypertension events, expected blood loss, postoperative nausea and vomiting and postoperative epidural hematoma were compared between the 2 groups. The 2 groups were homogeneous in terms of age, sex, weight, height, body mass index (BMI), ASA physical status (ASA PS), and diagnosis. The incidence of hypotension events (67.2 % in the NS group, 45.7 % in the EPI group, P =.015) and severe hypotension events (51.7 % in the NS group, 28.6 % in the EPI group, P = .015) were less frequent in the EPI group. Only epinephrine had a significant protective effect through a multivariable analysis (P = .027, OR = 2.361) and in severe hypotension events, only epinephrine had a significant protective effect through a multivariable analysis (P = .011, OR = 2.818), and EBL was the risk factor through a multivariable analysis (P = .016, OR = 1.002) We believe that the addition of epinephrine to irrigation saline has hemodynamic protective effects in patients who underwent endoscopic lumbar surgery.


Assuntos
Hipotensão , Solução Salina , Epinefrina/uso terapêutico , Hemodinâmica , Humanos , Hipotensão/etiologia , Estudos Retrospectivos
18.
Mol Syst Biol ; 18(5): e10630, 2022 05.
Artigo em Inglês | MEDLINE | ID: mdl-35507445

RESUMO

How the coexistence of species is affected by the presence of multiple resources is a major question in microbial ecology. We experimentally demonstrate that differences in diauxic lags, which occur as species deplete their own environments and adapt their metabolisms, allow slow-growing microbes to stably coexist with faster-growing species in multi-resource environments despite being excluded in single-resource environments. In our focal example, an Acinetobacter species (Aci2) competitively excludes Pseudomonas aurantiaca (Pa) on alanine and on glutamate. However, they coexist on the combination of both resources. Experiments reveal that Aci2 grows faster but Pa has shorter diauxic lags. We establish a tradeoff between Aci2's fast growth and Pa's short lags as their mechanism for coexistence. We model this tradeoff to accurately predict how environmental changes affect community composition. We extend our work by surveying a large set of competitions and observe coexistence nearly four times as frequently when the slow-grower is the fast-switcher. Our work illustrates a simple mechanism, based entirely on supplied-resource growth dynamics, for the emergence of multi-resource coexistence.


Assuntos
Adaptação Fisiológica , Ecossistema , Modelos Biológicos
19.
Materials (Basel) ; 15(5)2022 Mar 07.
Artigo em Inglês | MEDLINE | ID: mdl-35269190

RESUMO

High temperature conditions, such as fire, are detrimental factors to the mechanical and chemical properties of concrete. In this paper, the authors developed a new type of coarse aggregate, named PCM/SiC composite aggregate (enhanced aggregate: EA), to improve fire-resistance performance. To investigate the validity of EA for construction materials, a compressive strength test, static modulus of elasticity, X-ray diffraction (XRD), and scanning electron microscopy (SEM) were conducted. In addition, this EA has been developed to improve residual performance after exposure to high temperature, with residual compressive strength and internal temperature measurement tested at 1000 °C. Furthermore, chemical properties after heating were investigated by XRD and SEM-EDAX. The results show that the percentage of residual compressive strength of heated concrete with EA is higher than plain concrete. The concrete with EA exhibited primary cement composites such as C-H and C-S-H after exposure to high temperature through XRD and SEM-EDAX. On the other hand, major hydration products could not be observed in plain concrete. PCM and SiC offer an opportunity to delay the increase in concrete temperature. From evaluation of the results, we can see that EA enhanced the residual performance of concrete after exposure to high temperature conditions.

20.
Proc Natl Acad Sci U S A ; 119(1)2022 01 04.
Artigo em Inglês | MEDLINE | ID: mdl-34983839

RESUMO

Most organisms grow in space, whether they are viruses spreading within a host tissue or invasive species colonizing a new continent. Evolution typically selects for higher expansion rates during spatial growth, but it has been suggested that slower expanders can take over under certain conditions. Here, we report an experimental observation of such population dynamics. We demonstrate that mutants that grow slower in isolation nevertheless win in competition, not only when the two types are intermixed, but also when they are spatially segregated into sectors. The latter was thought to be impossible because previous studies focused exclusively on the global competitions mediated by expansion velocities, but overlooked the local competitions at sector boundaries. Local competition, however, can enhance the velocity of either type at the sector boundary and thus alter expansion dynamics. We developed a theory that accounts for both local and global competitions and describes all possible sector shapes. In particular, the theory predicted that a slower on its own, but more competitive, mutant forms a dented V-shaped sector as it takes over the expansion front. Such sectors were indeed observed experimentally, and their shapes matched quantitatively with the theory. In simulations, we further explored several mechanisms that could provide slow expanders with a local competitive advantage and showed that they are all well-described by our theory. Taken together, our results shed light on previously unexplored outcomes of spatial competition and establish a universal framework to understand evolutionary and ecological dynamics in expanding populations.


Assuntos
Enterobacteriaceae/crescimento & desenvolvimento , Espécies Introduzidas , Modelos Biológicos , Biofilmes , Meios de Cultura , Enterobacteriaceae/genética , Mutação
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