String Core Research Articles

Exploring the mechanism of action of the combination of cinnamon and motherwort in the treatment of benign prostatic hyperplasia: A network pharmacology study.

Cinnamon and motherwort are traditional Chinese medicines and are often combined to treat benign prostatic hyperplasia; however, the specific therapeutic mechanisms involved remain unclear. Therefore, in this study, we applied a network pharmacology approach to investigate the potential mechanisms of action of the drug pair cinnamon and motherwort (PCM) for the treatment of benign prostatic hyperplasia. Relevant targets for the use of PCM to treat benign prostatic hyperplasia were obtained through databases. Protein-protein interactions were then identified by the STRING database and core targets were screened. Enrichment analysis was conducted through the Metascape platform. Finally, molecular docking experiments were carried out to evaluate the affinity between the target proteins and ligands of PCM. We identified 22 active ingredients in PCM, 315 corresponding targets and 130 effective targets of PCM for the treatment of benign prostatic hyperplasia. These targets were related to the PI3K-Akt, MAPK, FoxO, TNF, and IL-17 signaling pathways. Network pharmacology was used to identify the effective components and action targets of PCM. We also identified potential mechanisms of action for PCM in the treatment of benign prostatic hyperplasia. Our results provide a foundation for expanding the clinical application of PCM and provide new ideas and directions for further research on the mechanisms of action of PCM and its components for the treatment of benign prostatic hyperplasia.

Identification of anti-gastric cancer effects and molecular mechanisms of resveratrol: From network pharmacology and bioinformatics to experimental validation.

Gastric cancer (GC) is one of the most aggressive malignancies with limited therapeutic options and a poor prognosis. Resveratrol, a non-flavonoid polyphenolic compound found in a variety of Chinese medicinal materials, has shown excellent anti-GC effect. However, its exact mechanisms of action in GC have not been clarified. To identify the effects of resveratrol on GC progression and explore the related molecular mechanisms. Action targets of resveratrol and GC-related targets were screened from public databases. The overlapping targets between the two were confirmed using a Venn diagram, and a "Resveratrol-Target-GC" network was constructed using Cytoscape software version 3.9.1. The protein-protein interaction (PPI) network was constructed using STRING database and core targets were identified by PPI network analysis. The Database for Annotation, Visualization and Integrated Discovery database was used for Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) enrichment analysis. A "Target-Pathway" network was created by using Cytoscape 3.9.1. The RNA and protein expression levels of core target genes were observed using the Cancer Genome Atlas and the Human Protein Atlas databases. DriverDBv3 and Timer2.0 databases were used for survival and immune infiltration analysis. Subsequently, the findings were further verified by molecular docking technology and in vitro experiments. A total of 378 resveratrol action targets and 2154 GC disease targets were obtained from public databases, and 181 intersection targets between the two were screened by Venn diagram. The top 20 core targets were identified by PPI network analysis of the overlapping targets. GO function analysis mainly involved protein binding, identical protein binding, cytoplasm, nucleus, negative regulation of apoptotic process and response to xenobiotic stimulus. KEGG enrichment analysis suggested that the involved signaling pathways mainly included PI3K-AKT signaling pathway, MAPK signaling pathway, IL-17 signaling pathway, TNF signaling pathway, ErbB signaling pathway, etc. FBJ murine osteosarcoma viral oncogene homolog (FOS) and matrix metallopeptidase 9 (MMP9) were selected by differential expression analysis, and they were closely associated with immune infiltration. Molecular docking results showed that resveratrol docked well with these two targets. Resveratrol treatment arrested the cell cycle at the S phase, induced apoptosis, and weakened viability, migration and invasion in a dose-dependent manner. Furthermore, resveratrol could exhibit anti-GC effect by regulating FOS and MMP9 expression. The anti-GC effects of resveratrol are related to the inhibition of cell proliferation, migration, invasion and induction of cell cycle arrest and apoptosis by targeting FOS and MMP9.

Network pharmacological study of Banxia-Chenpi in the treatment of cough variant asthma in children with phlegm evil accumulation lung syndrome

ObjectiveTo explore the molecular mechanism of Banxia -Chenpi in the treatment of cough variant asthma with phlegm evil accumulation lung syndrome based on network pharmacology and molecular docking technology. MethodsTCMSP database was used to screen the active ingredients and targets of Banxia-Chenpi. GeneCards, OMIM and PharmGKB databases were used to obtain the targets of cough variant asthma. Cytoscape 3.9.1 software was used to construct the “couplet medicines-active ingredients-targets” network and screen key ingredients according to the degree value. The protein–protein interaction data were obtained from the STRING database and core targets were screened by Cytoscape plugin cytoNCA. The core targets conduct GO and KEGG pathway enrichment analyses in the David database. Molecular docking technology was used to verify the binding energy between key ingredients and core targets. ResultsThere were 16 active ingredients and potential 118 targets in Banxia-Chenpi,2429 cough variant asthma targets, and 72 intersection targets. The key ingredients of the Banxia-Chenpi in treating cough variant asthma were nobiletin, baicalein, naringenin, stigmasterol, beta-sitosterol and coniferin. The core targets of the Banxia-Chenpi for CVA treatment were FOS, MMP9, AKT1, CASP3, TP53, JUN and VEGFA. The molecular docking results indicated key ingredients and core targets of the Banxia-Chenpi in CVA treatment had a good binding affinity. ConclusionActive ingredients maybe act on MMP9, AKT1, VEGFR and FOS to reduce eosinophils and neutrophils accumulation, dissolve phlegm, alleviate airway inflammation, and reduce airway resistance and hyperresponsiveness for treating CVA. This study provides a reference for clinical medication and subsequent research.

Red Ginseng Improves D-galactose-Induced Premature Ovarian Failure in Mice Based on Network Pharmacology.

In this study, we evaluated the ameliorative effect and molecular mechanism of red ginseng (Panax ginseng C.A. Meyer) extract (RGE) on D-galactose (D-gal)-induced premature ovarian failure (POF) using network pharmacology analysis. Ginsenosides are important active ingredients in ginseng, which also contains some sugar and amino acid derivatives. We aimed to determine the key proteins through which RGE regulates POF. In this work, we retrieved and screened for active ingredients in ginseng and the corresponding POF disease targets in multiple databases. A PPI network of genes was constructed in the STRING database and core targets were screened using topological analysis. Gene ontology and Kyoto Encyclopedia of Genes and Genomes enrichment analyses were conducted in R software. Finally, molecular docking was conducted to validate the results. Female ICR mice were used to establish a POF mouse model for in vivo experiments. Serum levels of relevant estrogens were determined using ELISA and expression levels of relevant proteins in ovarian tissues were detected using immunofluorescence and western blot analysis. Network pharmacology analysis predicted that PI3K, Akt, Bax, Bcl-2, p16, and other proteins were highly correlated with POF and RGE. The results clearly showed that RGE could increase estradiol (E2) and lower follicle-stimulating hormone (FSH) levels in D-gal-fed mice. RGE restored the expression levels of related proteins by reducing Nrf2-mediated oxidative stress, PI3K/Akt-mediated apoptosis, and senescence signaling pathways. Overall, RGE has the potential to prevent and treat POF and is likely to be a promising natural protector of the ovaries.

Exploring the Mechanism of Antioxidant Action of Bitter Almond Based on Network Pharmacology and Molecular Docking Techniques

Objective. A network pharmacology approach was used to investigate the main active ingredients, key targets, and mechanisms of action of bitter almond antioxidants, and preliminary validation of the relevant targets was performed using molecular docking techniques. Methods. The active ingredients of bitter almond were obtained through the traditional Chinese medicine systematic pharmacology database and analysis platform (TCMSP), and the main active ingredients were screened by bioavailability (OB) and drug-like properties (DL); the GeneCards database was used to search antioxidant-related disease targets through the traditional Chinese medicine systematic pharmacology database and analysis; building a “drug-disease-target” visual network map with Cytoscape 3.9.0 software; a protein interaction (PPI) network was constructed using STRING website and core targets were screened; GO function and KEGG pathway enrichment analysis were obtained using Metoscape. Finally, SailVina software was used to molecularly dock the major active ingredients and target proteins and visualize them using PyMOL software. Results. A total of 19 antioxidant active ingredients were obtained for bitter almond, mainly stigmasterol, glycyrol, and estrone. The targets regulated by their main active ingredients were intersected with oxidative targets, and 53 intersected targets were obtained by Venn diagram, with key targets involving NR3C2, NCOA2, MAOA, ADRA2A, and CHRM1; GO analysis yielded 3616 GO entries, including 2821 biological process (BP) entries, 316 cellular component (CC) entries, and 479 molecular function (MF) entries, and 184 signalling pathways were obtained from KEGG pathway enrichment screening. The molecular docking results showed that Stigmasterol-NR3C2 binding was better. Conclusion. Stigmasterol, glycyrol, estrone, and licochalcone B in bitter almond may be the material basis of antioxidant and have better antioxidant activity; therefore, bitter almond has the characteristics of multicomponent, multitarget and multipathway.

Therapeutic targets and signaling mechanisms of dasatinib activity against radiation skin ulcer.

To reveal the potential targets and signaling pathways of dasatinib in the treatment of radiation ulcers through network pharmacology and molecular docking technology. Pathological targets of radiation ulcers were screened using GeneCards database. At the same time, the pharmacological targets of dasatinib were obtained through SwissTargetPrediction (STP), Binding DB and Drugbank databases. Subsequently, the potential targets of dasatinib for anti-radiation ulcers were obtained after intersection by Venn diagram. Next, a protein-protein interaction (PPI) network was constructed through the STRING database and core targets were screened. Finally, the identified core targets were subjected to GO and KEGG enrichment analysis, co-expression network analysis, and molecular docking technology to verify the reliability of the core targets. A total of 76 potential targets for anti-radiation ulcer with dasatinib were obtained, and 6 core targets were screened, including EGFR, ERBB2, FYN, JAK2, KIT, and SRC. These genes were mainly enriched in Adherens junction, EGFR tyrosine kinase inhibitor resistance, Focal adhesion, Bladder cancer and PI3K-Akt signaling pathway. Molecular docking results showed that dasatinib binds well to the core target. Dasatinib may play a role in the treatment of radiation ulcers by regulating EGFR, ERBB2, FYN, JAK2, KIT, and SRC. These core targets may provide new insights for follow-up studies of radiation ulcers.

Exploring Mechanisms by Which Danggui Buxue Decoction Regulates Inflammation and Improves Renal Anemia Based on Network Pharmacology

Background: Renal anemia occurs frequently in patients with chronic kidney disease (CKD) and is related to chronic inflammation. Danggui Buxue Decoction (DBD) can treat anemia and improve the chronic inflammation. However, whether DBD treatment attenuates anemia by regulating inflammation in CKD patients with renal anemia is unknown. Therefore, this study explored inflammation-related network targets of DBD in renal anemia therapy and verified the interaction between DBD active ingredients and inflammatory proteins by molecular docking. Methods: The main effective components and targets of DBD were screened using the Traditional Chinese Medicine System Pharmacology Database and Analysis Platform. Renal anemia-related biomolecules were searched in the GeneCards, OMIM, TTD, Pharmgkb, and DrugBank databases. Protein-protein interaction (PPI) data were downloaded from the STRING database and core targets were obtained. Gene ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) enrichment analyses for core targets were performed. Finally, active ingredients and core biomolecules were determined using molecular docking. Results: Twenty-two active components and 158 targets for DBD treatment of renal anemia were screened, and an “ingredient-target” network was constructed. Twenty core target genes were screened from the PPI data. Vascular endothelial growth factor A, Signal Transducer and Activator of transcription 1, C-X-C motif chemokine ligand 8, post-transcriptional gene silencing 2, and interleukin (IL)-1β were identified as inflammatory proteins. GO items related to inflammation and DBD included lipopolysaccharide, cellular response to chemical stress, and oxidative stress-related reactions. KEGG enrichment analyses showed that core inflammatory pathways mainly involved the IL-17 signaling pathway, tumor necrosis factor signaling pathway, and phosphoinositide 3-kinase-protein kinase B signaling pathway. Molecular docking results indicated that the binding energy of quercetin, an active ingredient of DBD, to the 5 core proteins was less than −6 kcal·mol−1. Conclusion: DBD might have protective effects against renal anemia by improving inflammation. Quercetin might modulate multiple inflammatory proteins and pathways.

Fermionic vacuum polarization around a cosmic string in compactified AdS spacetime

We investigate topological effects of a cosmic string and compactificationof a spatial dimension on the vacuum expectation value (VEV) of theenergy-momentum tensor for a fermionic field in (4+1)-dimensional locallyAdS spacetime. The contribution induced by the compactification isexplicitly extracted by using the Abel-Plana summation formula. The meanenergy-momentum tensor is diagonal and the vacuum stresses along thedirection perpendicular to the AdS boundary and along the cosmic string areequal to the energy density. All the components are even periodic functionsof the magnetic fluxes inside the string core and enclosed by compactdimension, with the period equal to the flux quantum. The vacuum energydensity can be either positive or negative, depending on the values of theparameters and the distance from the string. The topological contributionsin the VEV of the energy-momentum tensor vanish on the AdS boundary. Nearthe string the effects of compactification and gravitational field are weakand the leading term in the asymptotic expansion coincides with thecorresponding VEV in (4+1)-dimensional Minkowski spacetime. At largedistances, the decay of the cosmic string induced contribution in the vacuumenergy-momentum tensor, as a function of the proper distance from thestring, follows a power law. For a cosmic string in the Minkowski bulk andfor massive fields the corresponding fall off is exponential. Within theframework of the AdS/CFT correspondence, the geometry for conformal fieldtheory on the AdS boundary corresponds to the standard cosmic string in(3+1)-dimensional Minkowski spacetime compactified along its axis.

Induced vacuum magnetic field in the cosmic string background

The relativistic charged spinor matter field is quantized in the background of a straight cosmic string with nonvanishing transverse size. The most general boundary conditions ensuring the impossibility for matter to penetrate through the edge of the string core are considered. The role of discrete symmetries is elucidated, and analytic expressions for the temporal and spatial components of the induced vacuum current are derived in the case of either $P$ or $CT$ invariant boundary condition with two parameters varying arbitrarily from point to point of the edge. The requirement of physical plausibility for the global induced vacuum characteristics is shown to remove completely an arbitrariness in boundary conditions. We find out that a magnetic field is induced in the vacuum and that a sheath in the form of a tube of the magnetic flux lines encloses a cosmic string. The dependence of the induced vacuum magnetic field strength on the string flux and tension, as well as on the transverse size of the string and on the distance from the string, is unambiguously determined.

On stability of fermionic superconducting current in cosmic string

Recently, the chiral superconductivity of the cosmic string in the axion model has gathered attention. The superconductive nature can alter the standard understanding of the cosmology of the axion model. For example, a string loop with a sizable super-conducting current can become a stable configuration, which is called a Vorton. The superconductive nature can also affect the cosmological evolution of the string network. In this paper, we study the stability of the superconducting current in the string. We find the superconductivity is indeed stable for a straight string or infinitely small string core size, even if the carrier particles are unstable in the vacuum. However we also find that the carrier particle decays in a curved string in typical axion models, if the carrier particles are unstable in the vacuum. Accordingly, the lifetime of the Vorton is not far from that of the carrier particle in the vacuum.

Decay of cosmic global string loops

We numerically study the decay of cosmic global string loops due to radiation of Goldstone bosons and massive scalar ($\chi$) particles. The length of loops we study range from 200-1000 times the width of the string core. We find that the lifetime of a loop is $\approx 1.4 L$. The energy spectrum of Goldstone boson radiation has a $k^{-1}$ fall off, where $k$ is the wavenumber, and a sharp peak at $k \approx m_\chi/2$, where $m_\chi$ is the mass of $\chi$. The latter is a new feature and implies a peak at high energies (MeV-GeV) in the cosmological distribution of QCD axions.

Exploration of omics mechanism and drug prediction of coronavirus-induced heart failure based on clinical bioinformatics

Objective: Present study investigated the mechanism of heart failure associated with coronavirus infection and predicted potential effective therapeutic drugs against heart failure associated with coronavirus infection. Methods: Coronavirus and heart failure were searched in the Gene Expression Omnibus (GEO) and omics data were selected to meet experimental requirements. Differentially expressed genes were analyzed using the Limma package in R language to screen for differentially expressed genes. The two sets of differential genes were introduced into the R language cluster Profiler package for gene ontology (GO) and Kyoto gene and genome encyclopedia (KEGG) pathway enrichment analysis. Two sets of intersections were taken. A protein interaction network was constructed for all differentially expressed genes using STRING database and core genes were screened. Finally, the apparently accurate treatment prediction platform (EpiMed) independently developed by the team was used to predict the therapeutic drug. Results: The GSE59185 coronavirus data set was searched and screened in the GEO database, and divided into wt group, ΔE group, Δ3 group, Δ5 group according to different subtypes, and compared with control group. After the difference analysis, 191 up-regulated genes and 18 down-regulated genes were defined. The GEO126062 heart failure data set was retrieved and screened from the GEO database. A total of 495 differentially expressed genes were screened, of which 165 were up-regulated and 330 were down-regulated. Correlation analysis of differentially expressed genes between coronavirus and heart failure was performed. After cross processing, there were 20 GO entries, which were mainly enriched in virus response, virus defense response, type Ⅰ interferon response, γ interferon regulation, innate immune response regulation, negative regulation of virus life cycle, replication regulation of viral genome, etc. There were 5 KEGG pathways, mainly interacting with tumor necrosis factor (TNF) signaling pathway, interleukin (IL)-17 signaling pathway, cytokine and receptor interaction, Toll-like receptor signaling pathway, human giant cells viral infection related. All differentially expressed genes were introduced into the STRING online analysis website for protein interaction network analysis, and core genes such as signal transducer and activator of transcription 3, IL-10, IL17, TNF, interferon regulatory factor 9, 2'-5'-oligoadenylate synthetase 1, mitogen-activated protein kinase 3, radical s-adenosyl methionine domain containing 2, c-x-c motif chemokine ligand 10, caspase 3 and other genes were screened. The drugs predicted by EpiMed's apparent precision treatment prediction platform for disease-drug association analysis were mainly TNF-α inhibitors, resveratrol, ritonavir, paeony, retinoic acid, forsythia, and houttuynia cordata. Conclusions: The abnormal activation of multiple inflammatory pathways may be the cause of heart failure in patients after coronavirus infection. Resveratrol, ritonavir, retinoic acid, amaranth, forsythia, houttuynia may have therapeutic effects. Future basic and clinical research is warranted to validate present results and hypothesis.

Axions from strings: the attractive solution

We study the system of axion strings that forms in the early Universe if the Peccei-Quinn symmetry is restored after inflation. Using numerical simulations, we establish the existence of an asymptotic solution to which the system is attracted independently of the initial conditions. We study in detail the properties of this solution, including the average number of strings per Hubble patch, the distribution of loops and long strings, the way that different types of radiation are emitted, and the shape of the spectrum of axions produced. We find clear evidence of logarithmic violations of the scaling properties of the attractor solution. We also find that, while most of the axions are emitted with momenta of order Hubble, most of the axion energy density is contained in axions with energy of order the string core scale, at least in the parameter range available in the simulation. While such a spectrum would lead to a negligible number density of relic axions from strings when extrapolated to the physical parameter region, we show that the presence of small logarithmic corrections to the spectrum shape could completely alter such a conclusion. A detailed understanding of the evolution of the axion spectrum is therefore crucial for a reliable estimate of the relic axion abundance from strings.

Scalar Casimir densities and forces for parallel plates in cosmic string spacetime

We analyze the Casimir densities and forces associated with a massive scalar quantum field confined between two parallel plates in a D-dimensional cosmic string spacetime. The plates are placed orthogonal to the string and the field obeys the Robin boundary conditions on them. The boundary-induced contributions are explicitly extracted in the vacuum expectation values (VEVs) of the field squared and energy-momentum tensor for both single and two plates. The VEV of the energy-momentum tensor, in additional to the diagonal components, contains an off-diagonal component corresponding to the shear stress. The latter vanishes on the plates in special cases of Dirichlet and Neumann boundary conditions. For points outside the string core the topological contributions in the VEVs are finite on the plates. Near the string the VEVs are dominated by the boundary-free part, whereas at large distances the boundary-induced contributions dominate. Due to the nonzero off-diagonal component of the vacuum energy-momentum tensor, in addition to the normal component, the Casimir forces have nonzero component parallel to the boundary. Unlike the problem on the Minkowski bulk, the normal forces acting on the separate plates, in general, do not coincide. Another difference is that in the presence of the cosmic string the Casimir forces for Dirichlet and Neumann boundary conditions differ. For Dirichlet case the normal Casimir force does not depend on the curvature coupling parameter. This is not the case for other boundary conditions. A new qualitative feature induced by the cosmic string is the appearance of the shear stress acting on the plates. The corresponding force is directed along the radial coordinate and vanishes for Dirichlet and Neumann cases. Depending on the parameters of the problem, the radial component of the shear force can be either positive or negative.

Wave propagation in metamaterials mimicking the topology of a cosmic string

We study the interference and diffraction of light when it propagates through a metamaterial medium mimicking the spacetime of a cosmic string—a topological defect with curvature singularity. The phenomenon may look like a gravitational analogue of the Aharonov–Bohm effect, since the light propagates in a region where the Riemann tensor vanishes, being nonetheless affected by the non-zero curvature confined to the string core. We carry out the full-wave numerical simulation of the metamaterial medium and give the analytical interpretation of the results by use of the asymptotic theory of diffraction, which turns out to be in excellent agreement. In particular, we show that the main features of wave propagation in a medium with conical singularity can be explained by four-wave interference involving two geometrical optics and two diffracted waves.

Vortex-strings in mathcal{N}=2 SQCD and bulk-string decoupling

We study vortex-strings in four-dimensional mathcal{N}=2 supersymmetric SU(Nc) × U(1) gauge theories with Nf hypermultiplets in the fundamental representation of SU(Nc) and general U(1) charges. If Nf> Nc, the vacuum is not gapped and the low-energy theory contains both the vacuum massless excitations and the string zero-modes. The question we address in this work is whether the vacuum and the string moduli decouple at low energies, allowing a description of the low-energy dynamics in terms of a two-dimensional theory on the string worldsheet. We find a simple condition controlling the bulk-string coupling: if there exist two flavors such that the product of their U(1) charge difference with the magnetic flux carried by the string configuration is not an integer multiple of 2π, the string has zero-modes that decay slower than 1/r, where r is the radial distance from the string core. These modes are coupled to the vacuum massless excitations even at low energies. If, however, all such products are integer multiples of 2π, long-range modes of this type do not exist and the string moduli decouple from the bulk at low energies. This condition turns out to coincide with the condition of trivial Aharonov-Bohm phases for the particles in the spectrum. In addition to a derivation of the bulk-string decoupling criterion using classical analysis of the string zero-modes, we provide a non-perturbative derivation of the criterion, which uses supersymmetric localization techniques.

Excited cosmic strings with superconducting currents

We present a detailed analysis of {\it excited} cosmic string solutions which possess superconducting currents. These currents can be excited inside the string core, and - if the condensate is large enough - can lead to the excitations of the Higgs field. Next to the case with global unbroken symmetry, we discuss also the effects of the gauging of this symmetry and show that excited condensates persist when coupled to an electromagnetic field. The space-time of such strings is also constructed by solving the Einstein equations numerically and we show how the local scalar curvature is modified by the excitation. We consider the relevance of our results on the cosmic string network evolution as well as observations of primordial gravitational waves and cosmic rays.

How to simulate global cosmic strings with large string tension

Global string networks may be relevant in axion production in the early Universe, as well as other cosmological scenarios. Such networks contain a large hierarchy of scales between the string core scale and the Hubble scale, ln(fa/H) ∼ 70, which influences the network dynamics by giving the strings large tensions T ≃ π fa2 ln(fa/H). We present a new numerical approach to simulate such global string networks, capturing the tension without an exponentially large lattice.

Quantum stabilization of a hedgehog type of cosmic string

Within a slightly simplified version of the electroweak standard model we investigate the stabilization of cosmic strings by fermion quantum fluctuations. Previous studies of quantum energies considered variants of the Nielsen–Olesen profile embedded in the electroweak gauge group and showed that configurations are favored for which the Higgs vacuum expectation value drops near the string core and the gauge field is suppressed. This work found that the strongest binding was obtained from strings that differ significantly from Nielsen–Olesen configurations, deforming essentially only the Higgs field in order to generate a strong attraction without inducing large gradients. Extending this analysis, we consider the leading quantum correction to the energy per unit length of a hedgehog type string, which, in contrast to the Nielsen–Olesen configuration, contains a pseudoscalar field. To employ the spectral method we develop the scattering and bound state problems for fermions in the background of a hedgehog string. Explicit occupation of bound state levels leads to strings that carry the quantum numbers of the bound fermions. We discuss the parameter space for which stable, hedgehog type cosmic strings emerge and reflect on phenomenological consequences of these findings.

Stability of the pion string in a thermal and dense medium

We investigate the stability of the pion string in a thermal bath and a dense medium. We find that stability is dependent on the order of the chiral transition. String core stability within the experimentally allowed regime is found only if the chiral transition is second order, and even there the stable region is small, i.e., the temperature below which the core is unstable is close to the critical temperature of the phase transition. We also find that the presence of a dense medium, in addition to the thermal bath, enhances the experimentally accessible region with stable strings. We also argue that once the string core decays, the "effective winding" of the string persists at large distances from the string core. Our analysis is done both in the chiral limit, which is mainly what has been explored in the literature up to now, and for the physical $h \ne 0$ case, where a conceptual framework is set up for addressing this regime and some simple estimates are done.