Alpha Cluster Research Articles

Study of the effect of the tensor correlation on the alpha–alpha interaction in 8Be with the charge- and parity-projected Hartree–Fock method

We study the effect of the tensor correlation on the alpha–alpha interaction in 8Be using an alpha cluster model. We use the wave function of the alpha particle calculated with the charge- and parity-projected Hartree–Fock method, which can treat the effect of the tensor correlation. The expectation value of the potential energy from the tensor force in 8Be is almost twice of that in the alpha particle and the tensor correlation energy between two alpha particles is a few MeV. The energy surface as a function of the relative distance between two alpha particles becomes much steeper in an inner region by the inclusion of the tensor correlation in the wave function of the alpha particle. This is caused by the p-state mixing induced by the tensor force. By superposing the wave functions with different relative distances, the reasonable binding energy of 8Be is obtained.

Differential expression of four protocadherin alpha and gamma clusters in the developing and adult zebrafish: DrPcdh2γ but not DrPcdh1γ is expressed in neuronal precursor cells, ependymal cells and non-neural epithelia

Protocadherins are cadherin-like molecules with adhesive and signaling functions, in particular, during neuronal development. Large protocadherin (Pcdh) gene clusters are present in the genome of vertebrates. In the zebrafish, two Pcdh clusters are found on chromosomes 10 (DrPcdh1) and 14 (DrPcdh2), each divided into subclusters of DrPcdhalpha and DrPcdhgamma family genes. In total, about 100 different DrPcdh molecules are predicted. We have analyzed the expression of the four DrPcdh subclusters and find that DrPcdh transcripts are upregulated in the developing zebrafish nervous system. In the adult fish brain, all four DrPcdh clusters are expressed in differentiated neurons, in particular, in the thalamic nuclei, tectum, and cerebellum. We show that expression patterns grossly overlap for each cluster but with regional differences and variations in strength of expression. Strikingly, the DrPcdh2gamma cluster, distinct from the three other clusters, is also expressed in neuronal precursor cells and ependymal cells of the embryonic and adult nervous system, as well as in specific non-neuronal epithelia. Antibodies to a conserved motif in the constant region of DrPcdh2gamma stain fiber tracts and neuropil of the zebrafish brain and cell-cell junctions in epithelia. Our results indicate that multiple DrPcdhs of the different clusters are expressed in differentiated zebrafish neurons, suggesting evolutionarily conserved functions of protocadherin clusters in cell adhesion and signaling. In addition, DrPcdh2gamma may exert more specific roles in neuronal precursor and non-neural epithelial cells, which have not yet been described for mammalian Pcdhgamma. Thus, our findings in zebrafish open new perspectives to examine these functions in other vertebrate model organisms.

Long-range chromosomal interactions regulate the timing of the transition between poised and active gene expression

To understand how mammalian genes are regulated from their natural chromosomal environment, we have analysed the molecular events occurring throughout a 150 kb chromatin segment containing the alpha globin gene locus as it changes from a poised, silent state in erythroid progenitors, to the fully activated state in late, erythroid cells. Active transcription requires the late recruitment of general transcription factors, mediator and Pol II not only to the promoter but also to its remote regulatory elements. Natural mutants of the alpha cluster show that whereas recruitment of the pre-initiation complex to the upstream elements occurs independently, recruitment to the promoter is largely dependent on the regulatory elements. An improved, quantitative chromosome conformation capture analysis demonstrates that this recruitment is associated with a conformational change, in vivo, apposing the promoter with its remote regulators, consistent with a chromosome looping mechanism. These findings point to a general mechanism by which a gene can be held in a poised state until the appropriate stage for expression, coordinating the level and timing of gene expression during terminal differentiation.

Secreted Protein Acidic and Rich in Cysteine (SPARC) Inhibits Integrin-Mediated Adhesion and Growth Factor-Dependent Survival Signaling in Ovarian Cancer

The matricellular glycoprotein SPARC (secreted protein acidic and rich in cysteine) has been accorded major roles in regulation of cell adhesion and proliferation, as well as tumorigenesis and metastasis. We have recently reported that in addition to its potent antiproliferative and proapoptotic functions, SPARC also abrogates ovarian carcinoma cell adhesion, a key step in peritoneal implantation. However, the underlying molecular mechanism through which SPARC ameliorates peritoneal ovarian carcinomatosis seems to be multifaceted and has yet to be delineated. Herein, we show that SPARC significantly inhibited integrin-mediated ovarian cancer cell adhesion to extracellular matrix proteins, as well as to peritoneal mesothelial cells. This counteradhesive effect of SPARC was shown to be mediated in part through significant attenuation of cell surface expression and clustering of alpha(v)-integrin subunit, alpha(v)beta(3)- and alpha(v)beta(5)-heterodimers, and beta(1)-subunit, albeit to a lesser extent, in ovarian cancer cells. Moreover, SPARC significantly suppressed both anchorage-dependent and -independent activation of AKT and mitogen-acti-vated protein kinase survival signaling pathways in ovarian cancer cells in response to serum and epidermal growth factor stimulation. In summary, we have identified a novel role of SPARC as a negative regulator of both integrin-mediated adhesion and growth factor-stimulated survival signaling pathways in ovarian cancer.

Sequencing and comparative analysis of fugu protocadherin clusters reveal diversity of protocadherin genes among teleosts

BackgroundThe synaptic cell adhesion molecules, protocadherins, are a vertebrate innovation that accompanied the emergence of the neural tube and the elaborate central nervous system. In mammals, the protocadherins are encoded by three closely-linked clusters (α, β and γ) of tandem genes and are hypothesized to provide a molecular code for specifying the remarkably-diverse neural connections in the central nervous system. Like mammals, the coelacanth, a lobe-finned fish, contains a single protocadherin locus, also arranged into α, β and γ clusters. Zebrafish, however, possesses two protocadherin loci that contain more than twice the number of genes as the coelacanth, but arranged only into α and γ clusters. To gain further insight into the evolutionary history of protocadherin clusters, we have sequenced and analyzed protocadherin clusters from the compact genome of the pufferfish, Fugu rubripes.ResultsFugu contains two unlinked protocadherin loci, Pcdh1 and Pcdh2, that collectively consist of at least 77 genes. The fugu Pcdh1 locus has been subject to extensive degeneration, resulting in the complete loss of Pcdh1γ cluster. The fugu Pcdh genes have undergone lineage-specific regional gene conversion processes that have resulted in a remarkable regional sequence homogenization among paralogs in the same subcluster. Phylogenetic analyses show that most protocadherin genes are orthologous between fugu and zebrafish either individually or as paralog groups. Based on the inferred phylogenetic relationships of fugu and zebrafish genes, we have reconstructed the evolutionary history of protocadherin clusters in the teleost fish lineage.ConclusionOur results demonstrate the exceptional evolutionary dynamism of protocadherin genes in vertebrates in general, and in teleost fishes in particular. Besides the 'fish-specific' whole genome duplication, the evolution of protocadherin genes in teleost fishes is influenced by lineage-specific gene losses, tandem gene duplications and regional sequence homogenization. The dynamic protocadherin clusters might have led to the diversification of neural circuitry among teleosts, and contributed to the behavioral and physiological diversity of teleosts.

P2Y2 receptors induced cell surface redistribution of αv integrin is required for activation of ERK 1/2 in U937 cells

Nucleotides released from cells due to stress, injury or inflammation, induce mitogenic effects in monocytes via activation of P2Y(2) nucleotide receptors (P2Y(2)Rs). Here we show that P2Y(2) nucleotide receptors in U937 monocytic cells regulate the activation of extracellular signal-regulated kinases 1 and 2 (ERK 1/2) by inducing the clustering of alpha(v) integrins. The activation of phosphatidylinositol 3-kinase by P2Y(2)R ligands was required for alpha(v) clustering, suggesting a means whereby two different classes of receptors communicate to induce mitogenic responses in monocytic cells. P2Y(2)R-induced alpha(v) clustering was also associated with a flattened phenotype of the U937 cells, consistent with the role of the P2Y(2)R in regulating early events in cell migration.

Four Novel Deletions in Globin Genes Revealed by Multiplex Ligation Dependent Probe Amplification Assay (MLPA) Technology.

For nearly 2 decades, the Hadassah Hospital hematology laboratory has been performing DNA-based diagnosis of thalassemia patients and carriers of alpha and beta thalassemia trait. Despite exhaustive analysis using conventional methods, no mutation or deletion could be identified for several families. Recently, MLPA technology was successfully applied to the diagnosis of deletions of alpha and beta globin genes (Harteveld, 2005). This method uses 2 sets (of 35 and 50 probes) covering 700 kb of alpha-globin and 500 Kb of beta-globin, respectively. In the current study, we applied this technology to the analysis of four additional families. Three are Ashkenazi Jews with suspected thalassemia trait. The fourth is a Persian Jewish patient with HbH disease who was only found to have -α 3.7, with an unknown deletion of two alpha genes on the other chromosome. Hematological data are presented in Table 1. MPLA analysis revealed that three of the propositi (2 of the Ashkenazim and the Persian patient) carried large deletions of the alpha globin locus and the third Ashkenazi family carried a large deletion of the beta globin locus, all of which are previously undescribed. Family C was found to have a deletion encompassing a region upstream of the alpha globin cluster but the alpha-like genes are all present. Family K has a large deletion removing the entire alpha globin cluster. The Persian patient has a large deletion of 2 alpha globin genes. Lastly, Family M, of Ashkenazi origin, carries a large deletion of the beta globin cluster whose 5′ end has not yet been mapped. Notably, this family has no elevation of HbA2 or HbF to indicate that they carry beta-thalassemia trait. We conclude that, while large deletions of the alpha or beta globin cluster are not common, they can present a serious problem in diagnosis, potentially leading to erroneous genetic counseling. Identification of such deletions can allow accurate genetic counseling and prenatal diagnosis in appropriate families. MPLA technology is invaluable in characterizing these types of deletions which escape detection using more conventional techniques.Hematological data of Patients and FamiliesName, Ethnicity (sex, age)RBCHbMCVMCHRDWHb EPFamily C, AshkenaziFamily C Mother (34y)4.011.48728.514.3Family C Father (38y)6.0813.57122.215.7Family C Child I (F, 8y)5.5111.16320.114.8Family C Child II (M, 6y)5.9111.96520.115.9Family C Child III (F, 2.5y)4.1111.584.627.716.1Family K, AshkenaziFamily K Propositus (M, 31y)6.6314.169.421.314.9Family MF, PersianFamily MF Propositus (M, 37y)5.519.756.717.523.7HbH 6%Family M (beta thal), AshkezaniFamily M Mother (38y)5.4610.763.919.614.8HbA2 2.8%Family M Father (51y)5.0713.380.326.213.2HbA2 2.2%Family M Child I (F, 17y)4.8514.286.729.312HbA2 2.6%Family M Child II (F, 13y)5.4310.662.319.514.8HbA2 2.5%Family M Child III (F, 11y)4.4312.283.427.412.7HbA2 2.4%Family M Child IV (F, 4y)6.3211.256.717.716.5HbA2 2.5%

Experimental and Theoretical Investigations of the Sulfite‐Based Polyoxometalate Cluster Redox Series: α‐ and β‐[Mo18O54(SO3)2]4−/5−/6−

The synthesis, isolation and structural characterization of the sulfite polyoxomolybdate clusters alpha-(D(3h))(C(20)H(44)N)(4){alpha-[Mo(18)O(54)(SO(3))(2)]}CH(3)CN and beta-(D(3d))(C(20)H(44)N)(4){beta-[Mo(18)O(54)(SO(3))(2)]}CH(3)CN is presented. Voltammetric studies in acetonitrile (0.1 M Hx(4)NClO(4), Hx(4)N=tetra-n-hexylammonium) reveal the presence of an extensive series of six one-electron reduction processes for both isomers. Under conditions of bulk electrolysis, the initial [Mo(18)O(54)(SO(3))(2)](4-/5-) and [Mo(18)O(54)(SO(3))(2)](5-/6-) processes produce stable [Mo(18)O(54)(SO(3))(2)](5-) and [Mo(18)O(54)(SO(3))(2)](6-) species, respectively, and the same reduced species may be produced by photochemical reduction. Spectroelectrochemical data imply that retention of structural form results upon reduction, so that both alpha and beta isomers are available at each of the 4-, 5-, and 6-redox levels. However, the alpha isomer is the thermodynamically favored species in both the one- and two-electron-reduced states, with beta-->alpha isomerization being detected in both cases on long time scales (days). EPR spectra also imply that increasing localization of the unpaired electron occurs over the alpha- and beta-[Mo(18)O(54)(SO(3))(2)](5-) frameworks as the temperature approaches 2 K where the EPR spectra show orthorhombic symmetry with different g and hyperfine values for the alpha and beta isomers. Theoretical studies support the observation that it is easier to reduce the alpha cluster than the beta form and also provide insight into the driving force for beta-->alpha isomerization in the reduced state. Data are compared with that obtained for the well studied alpha-[Mo(18)O(54)(SO(4))(2))](4-) sulfate cluster.

Local atomic arrangements and electronic structure of Zr-Ni-Al bulk metallic glass: –Analysis by use of the relevant crystals–

Internal energy of a bulk metallic glass (BMG) was investigated by making full use of its relevant crystals. The local atomic arrangements commonly existing both in the BMG and the relevant crystals were identified using experimentally determined radial distribution functions. The electronic structure of the relevant crystals was investigated by discrete variational X alpha (DVX α ) cluster calculations and high-resolution photoemission spectroscopy. The present analysis on the electronic structure revealed that the simultaneous formations of characteristic cluster levels and a pseudogap at the Fermi level effectively reduce the internal energy to stabilize BMGs.

Transfer, sequential decay, and quasi-free reactions induced by 18-MeV 6He beam on 6Li, 7Li, and 12C

The He-6 + Li-6,Li-7 and He-6 + C-12 scattering and reactions have been studied using an 18-MeV He-6 beam. Experimental results for the elastic scattering on all three targets are in fair agreement with optical model predictions, using the potentials found in the analysis of the Li-6 scattering on the same targets and at close beam energies. Several two-body exit channels show clear signatures of a direct reaction mechanism allowing extraction of spectroscopic information. The measured angular distribution for the He-6 + Li-6 --> alpha + Li-8 reaction indicated close similarity between the alpha + 2n configuration in He-6 and the alpha + d configuration in Li-6. The obtained results for alpha-particle pickup from both Li-6 and Li-7 give large values of a spectroscopic factors for some Be-10 states, indicating their well-developed alpha + He-6 cluster structure. The exotic two-proton pickup reaction (He-6, Be-8) was studied, as well as two-neutron and triton transfer reactions. Quasi-free scattering of He-6 on deuteron and a particle in Li-6 was also observed. The sequential decay reactions He-6 + Li-6 --> He-6 + alpha + d, He-6 + Li-6 --> 2 alpha + t + n, He-6 + Li-7 --> He-6 + alpha + t, and He-6 + C-12 --> Be-10 + 2 alpha were clearly seen, and alpha clustering of some states in Li-6,Li-7, Be8-10, and C-14 was thus studied. Several new spectroscopic results obtained for some Be-10 states support the existence of a molecule-like rotational band in Be-10 with a very large moment of inertia.

Alpha Clusters: Creative Innovation in Local Economies

This article examines a set of industries including financial investment, fashion, and culture that tend to predominate in certain cities such as New York and London. Using data on business establishments and wages for the United States and Canada, the author shows that these industries exhibit a very high level of spatial concentration and a related high level of wage variation among metropolitan areas. The author proposes that these industries are very cluster dependent because of an inherently rapid pace of product innovation. The implications of this for economic development analysis are considered in the context of cluster and innovation policy. The author suggests that fostering innovation in these industries requires a substantially different approach from that commonly being deployed for technology industries.

Identification of a tandem duplicated array in the Rhox α locus on mouse chromosome X

The Rhox family of homeobox-containing genes maps to three gene dense clusters, alpha, beta, and gamma, on the mouse X chromosome. Rhox genes are expressed primarily in reproductive and extra-embryonic tissues and may be regulated by colinear mechanisms. Uniquely among family members, Rhox4 is also expressed in the developing and adult thymus, where its striking restriction to the third pharyngeal pouch has suggested a role in lineage specification. In this article we describe a previously unreported duplication within the Rhox alpha locus that contains seven copies of Rhox4 and eight copies of Rhox2 and Rhox3 in a tandem array. We further show that all seven Rhox4 copies are expressed, although preferential expression occurs and differs between tissues. In contrast to reproductive tissues, we found no evidence of colinear expression of the Rhox alpha cluster during thymus development. All subspecies of mice examined contained multiple copies of Rhox4. However, the only predicted ortholog of Rhox4, rat Rhox4, is present in a single copy, suggesting that the duplications arose at the time of rat and mouse lineage divergence. Finally, no changes in Rhox4 expression were detected in mice with defects in thymus organogenesis, placing it upstream or outside of established transcriptional pathways.

Adaptive parallel job scheduling with flexible coscheduling

Many scientific and high-performance computing applications consist of multiple processes running on different processors that communicate frequently. Because of their synchronization needs, these applications can suffer severe performance penalties if their processes are not all coscheduled to run together. Two common approaches to coscheduling jobs are batch scheduling, wherein nodes are dedicated for the duration of the run, and gang scheduling, wherein time slicing is coordinated across processors. Both work well when jobs are load-balanced and make use of the entire parallel machine. However, these conditions are rarely met and most realistic workloads consequently suffer from both internal and external fragmentation, in which resources and processors are left idle because jobs cannot be packed with perfect efficiency. This situation leads to reduced utilization and suboptimal performance. Flexible coscheduling (FCS) addresses this problem by monitoring each job's computation granularity and communication pattern and scheduling jobs based on their synchronization and load-balancing requirements. In particular, jobs that do not require stringent synchronization are identified, and are not coscheduled; instead, these processes are used to reduce fragmentation. FCS has been fully implemented on top of the STORM resource manager on a 256-processor alpha cluster and compared to batch, gang, and implicit coscheduling algorithms. This paper describes in detail the implementation of FCS and its performance evaluation with a variety of workloads, including large-scale benchmarks, scientific applications, and dynamic workloads. The experimental results show that FCS saturates at higher loads than other algorithms (up to 54 percent higher in some cases), and displays lower response times and slowdown than the other algorithms in nearly all scenarios.

Calcium oscillation and phosphatidylinositol 3-kinase positively regulate integrin αIIbβ3-mediated outside-in signaling

The frequency of calcium oscillation reveals the platelet activation status, however, the biological significance of the periodic calcium responses and methods of communication with other integrin-mediated signals are not clear. RGD-containing disintegrin rhodostomin coated substrates were employed to enhance platelet spreading and calcium oscillation through direct binding and clustering of the receptor integrin alpha(IIb)beta3. The results showed that the activation of phosphatidylinositol 3-kinase (PI3-K) and internal calcium pathways were crucial for alpha(IIb)beta3 outside-in signaling. PI3-K antagonists wortmannin and LY294002 inhibited disintegrin substrates and induced platelet spreading and calcium oscillation. At the same time, pretreatment of platelets with the microsomal calcium-ATPase inhibitor thapsigargin to deplete internal calcium stores severely impaired the calcium oscillation as well as PI3-K activation and spreading on disintegrin substrates. Because inhibition of one pathway could inhibit the other, our data indicates that PI3-K and calcium oscillation are synergistically operated and form a positive-feedback regulation in integrin alpha(IIb)beta3-mediated outside-in signaling.

Charge- and parity-projected Hartree–Fock method for the tensor correlation and its application to light nuclei

We propose a meanfield framework which can treat the correlation induced by the tensor force. To treat the tensor force, we introduce a singe-particle state which is a mixing state of two parities, positive and negative and of two charge states, proton and neutron. We perform both parity and charge projections for a total wave function before variation and obtain a Hartree–Fock-like equation, the charge- and parity-projected Hartree–Fock equation. We apply the equation to the alpha particle and find that a finite tensor correlation is obtained with our method. We also calculate a energy surface for a two-alpha system to study the effect of the tensor force for the alpha clustering in 8Be.

Sequencing and mapping hemoglobin gene clusters in the Australian model dasyurid marsupial Sminthopsis macroura

Comparing globin genes and their flanking sequences across many species has allowed globin gene evolution to be reconstructed in great detail. Marsupial globin sequences have proved to be of exceptional significance. A previous finding of a β(beta)-like ω(omega) gene in the α(alpha) cluster in the tammar wallaby suggested that the α and β cluster evolved via genome duplication and loss rather than tandem duplication. To confirm and extend this important finding we isolated and sequenced BACs containing the α and β loci from the distantly related Australian marsupial Sminthopsis macroura. We report that the α gene lies in the same BAC as the β-like ω gene, implying that the α-ω juxtaposition is likely to be conserved in all marsupials. The LUC7L gene was found 3′ of the S. macroura α locus, a gene order shared with humans but not mouse, chicken or fugu. Sequencing a BAC contig that contained the S. macroura β globin and Ε globin loci showed that the globin cluster is flanked by olfactory genes, demonstrating a gene arrangement conserved for over 180 MY. Analysis of the region 5′ to the S. macroura epsilon (Ε) globin gene revealed a region similar to the eutherian LCR, containing sequences and potential transcription factor binding sites with homology to eutherian hypersensitive sites 1 to 5. FISH mapping of BACs containing S. macroura α and β globin genes located the β globin cluster on chromosome 3q and the α locus close to the centromere on 1q, resolving contradictory map locations obtained by previous radioactive in situ hybridization.

Projected multicluster model with Jastrow and linear state dependent correlations for12⩽A⩽16nuclei

Variational wave functions based on a Margenau-Brink cluster model with short-range and state-dependent correlations and angular momentum projection are obtained for some nuclei with $12\ensuremath{\leqslant}A\ensuremath{\leqslant}16$. The calculations have been carried out starting from the nucleon-nucleon interaction by using the variational Monte Carlo method. The configuration used consists of three alpha clusters located at the apexes of an equilateral triangle and an additional cluster, not necessarily of alpha type, forming a tetrahedron. This cluster is located at the top of its height. Short-range and state dependent correlations are included by means of a central Jastrow factor and a linear operatorial correlation factor, respectively. Angular momentum projection is performed by using the Peierls-Yoccoz operators. Optimal structures are obtained for all the nuclei studied. Some aspects of our methodology have been tested by comparing with previous calculations carried out without short-range correlations. The binding energy, the root mean square radius, and the one- and two-body densities are reported. The effects of correlations on both the energy and nucleon distributions are analyzed systematically.

Comprehensive analysis of the 9p21 region in neuroblastoma suggests a role for genes mapping to 9p21-23 in the biology of favourable stage 4 tumours.

Chromosome 9p21 is frequently deleted in many cancers. Previous reports have indicated that 9p21 LOH is an uncommon finding in neuroblastoma (NB), a tumour of childhood. We have performed an extensive analysis of 9p21 and genes located in this region (cyclin-dependent kinase inhibitor 2A – CDKN2A/p16INK4a, CDKN2A/p14ARF, CDKN2B/p15INK4b, MTAP, interferon α and β cluster). LOH was detected in 16.4% of 177 NB. The SRO was identified between markers D9S1751 and D9S254, at 9p21–23, a region telomeric to the CDKN2A and MTAP genes. A significantly better overall and progression-free survival was detected in stage 4 patients displaying 9p21–23 LOH. Hemizygous deletion of the region harbouring the CDKN2A and CDKN2B loci was identified in two tumours by means of fluorescent in situ hybridisation and MTAP was present by immunostaining in all but one tumour analysed. The transcriptional profile of tumours with 9p21–23 LOH was compared to that of NB displaying normal 9p21–23 status by means of oligonucleotide microarrays. Four of the 363 probe sets downregulated in tumours with 9p21–23 LOH were encoded by genes mapping to 9p22–24. The only well-characterised transcript among them was nuclear factor I-B3. Our results suggest a role for genes located telomeric of 9p21 in good risk NB.

Some Correlations Between Light Nuclear Phenomena and an Extended Nuclear Cluster Model.

The problem of modelling nuclear structure is analysed by extending the alpha cluster model to include the three-body mirror nuclei and the deuteron. It is possible to arrange all the nucleons of any nuclide into a set of from one to three of the four cluster types according to two principles, which are: (1) bound nucleons tend to form the alpha cluster and (2) nucleon excess is conserved by the three-body mirror clusters. In this analysis, each excess neutron forms a triton and each protonrich, odd-neutron nuclide forms one 3He. Within the series of isotopes for each element nuclear structure is discrete and reactive; the addition or removal of a single neutron changes its set of constituent clusters. The mass range of the isotopes of any element is defined by the model to be Z+1<A<3Z. The model correlates structure with a number of light nuclear phenomena, including the β-decay potential and the neutron emission decay mode. The recently observed islands of particle stability beyond the neutron drip-line of fluorine, neon and sodium are analysed as the highest mass isotope of each of those elements coupled to four neutrons, which is interpreted as the bound analogue of the recently observed free tetraneutron.

Unfavored alpha-decays of nuclei in cluster model

The alpha-cluster probability that represents the preformation of alpha particle in alpha-decay nuclei was determined for high-intensity alpha-decay mode odd-A and odd–odd heavy nuclei, 82<Z<114, 111<N<174. This probability was calculated using the energy-dependent formula derived from the formulation of clusterisation states representation (CSR) and the hypothesised cluster-formation model (CFM) as in our previous work. Our previous successful determination of phenomenological values of alpha-cluster preformation factors for even–even nuclei motivated us to expand the work to cover other types of nuclei. The formation energy of interior alpha cluster needed to be derived for the different nuclear systems with considering the unpaired-nucleon effect. The results showed the phenomenological value of alpha preformation probability and reflected the unpaired nucleon effect and the magic and sub-magic effects in nuclei. These results and their analyses presented are very useful for future work concerning the calculation of the alpha decay constants and the progress of its theory.