The phase-change memory (PCM) technology represents one of the most attractive concepts for next generation data storage. PCM behavior is mainly limited by the structural relaxation (SR) and by the ...crystallization of an amorphous chalcogenide material: the ternary alloy Ge 2 Sb 2 Te 5 . SR is a local structural-rearrangement at the atomic/bonding scale and crystallization is the reaching of a periodic atomic structure. While the retention capabilities related to crystallization have been already extensively addressed in the literature, both at the single-cell and at the statistical level, those related to SR have been mainly studied at the intrinsic level and a statistical analysis at the device level is still lacking. The purpose of this paper is to study the statistical and scaling behavior of the SR phenomenon in PCM devices, through experimental and modeling tools, allowing for long term, physics-based, reliability extrapolations in large-scaled PCM arrays.
The phase-change memory (PCM) technology represents one of the most attractive concepts for next generation data storage. PCM operation is based on the particular properties of a chalcogenide alloy, ...the ternary compound Ge 2 Sb 2 Te 5 , which is able to perform fast and reversible transitions between a crystalline, high-conductive phase and an amorphous, low-conductive one, thus enabling the binary data storage. Although the ternary alloy Ge 2 Sb 2 Te 5 is the best recognised solution to meet the device reliability and performance specifications, other alloys are being studied within the GeSbT e ternary compound system in order to investigate and to enlarge the possible spectrum of PCM applications. This work focuses both on the program parameters and on the write performances of a Sb-rich GST composition, suggesting a change in the physical properties of the PCM material and a transition from nucleation to growth-dominated crystallization mechanism, both controlled by the material composition engineering. This enables new challenging performance parameters.
Atomic migration on Phase Change Memory devices with wall architecture has been experimentally investigated and a quantitative model including electrical, thermal, and mechanical driving forces has ...been developed. The experimental results collected by driving the device with programming pulses with direct and reverse polarity have been accounted for. Comparison with data of atomic migration on heavily cycled cells is also provided.
Cervical lesions from penetrating trauma in the neck are increasing together with other types of trauma especially in big towns. Nevertheless in Italy a Register of Trauma is still lacking and no ...guidelines are available. Conservative management is also advocated and is still under discussion. Comparison of diagnostic tools and evaluation of different treatments in case of vascular damage is also expected.
A series of 16 penetrating lesions of the neck including various degrees of severity were treated over a span of 5 year. The penetrating trauma was due to stab wound or similar causes in 11 cases; to gunshot wound in 3 and to traffic accidents in 2 cases. All of them received surgical treatment. In 56% of cases (9/16) of cases vascular structures were involved, in 4 cases the aerodigestive tract was involved (25%), and in 1 the spinal cord was injured (6%) resulting in a Brown-Sequard syndrome. Other patients presented with superficial lesions, and reconstruction of muscles by simple suture or ligature of veins could obtain complete healing.
The penetrating trauma brought about death in 2 cases (1 stab wound, 1 gunshot wound), while 1 lesion of carotid artery and 4 lesions of jugular vein were successfully repaired. In 1 case of lesion in zone 3 a serious bleeding from damage to lingual artery was cured in spite of the minimal width of the external injury. Hypopharyngeal lesions could be treated in 2 cases. One was associated with lethal vascular damage. In 1 case of tracheal lesion with cervical hematoma and dyspnea, patency of the airways became the main concern and and a cannula was placed in the trachea. The Brown-Séquard syndrome could improve with rehabilitation therapy in 3 years. All of the minimal cervical lesions healed with uneventful course.
The penetrating trauma in the neck may show various degrees of severity: nevertheless, no cervical penetrating trauma should be underestimated in spite of the minimal width of the lesion. Surgical exploration was invariably the preferred treatment in our experience.
The phase change active material exploration represents an important stage in order to further strengthen the know-how on the Phase Change Memory (PCM) technology. This work reports a path for PCM ...material exploration toward the tellurium poor region of the GeSbTe (GST) ternary compound system. Data retention enhancement is reported and associated to a factor 1.5 increase of the crystallization activation energy. A detailed description and discussion of the remarkable electrical and thermal parameters of the PCM cell as a function of GST composition is provided.
The outcome of surgery in gastric cancer differs in Japan and Western countries and the extension of lymphadenectomy may play a crucial role in survival. In Japan the choice of performing extended ...(D2) and superextended (D4) lymphadenectomies is based on retrospective studies, and a prospective randomized study comparing D2 and D4 is still in course. In Western countries the randomized trials comparing D1 and D2 could not provide definite indications, D2 is not yet performed as a routine procedure and D4 is accepted only by few surgeons. We report our experience and discuss indications and results.
Since January 2000 through December 2002 we performed 27 superextended lymphadenectomies for the radical treatment of advanced gastric cancer. Early gastric cancers and patients over 80 years of age received conventional D2 gastrectomies. Selection of patients for D4 was made after laparotomy, when intraoperative peritoneal lavage cytology could rule out the presence of malignant cells, while D2 was done in case of peritoneal micrometastases.
Every patients had 39.5 nodes removed on average (range 17-94), and micrometastases in tier 16 were found in 7 cases (26%). Early post-operative surgical morbidity was 18% (5 patients) and mortality was 3.7% (1 patient). As much as 30% of patients complained of diarrhea as a late complication. The follow up could demonstrate a 3 year overall actuarial survival of 76%. Actuarial survival was 100% for N- and 70% for N+. A remarkable data was that 4 out of 5 patients who died from recurrence in the follow-up, were N4+. Actuarial survival at 3 years for N4+ patients was 34%, and the difference in survival between N4+ and other N+ was statistically significant (p<0.05).
Superextended lymphadenectomy in gastric cancer is feasible with postoperative morbidity and mortality rates not exceeding the rates of other lymphadenectomies. Actuarial survival at 3 years with D4 was better than in previous personal experience with D2, although the patients who underwent D4 were selected by intraperitoneal lavage cytology, while D2 patients had not been selected. The prognosis for N4- patients was better than for N4+ with micrometastases in tier 16. The presence of N4 micrometastases worsens the prognosis, but it is still uncertain whether D4 does improve survival: it is undoubtedly a new means of more accurate staging in gastric cancer surgery. The newer TNM classification regards the number of nodes removed as an indicator of radicality. Every surgeon should consider that superextended lymphadenectomies could comply with R0 radicality, and perform it within the ranges of low morbidity and mortality, until randomized trials with definitive results are available.
Although many studies on laparoscopic surgery of the stomach have been conducted so far, yet they have not provided surgeons with criteria for gradual and safe training with this technique. The ...results of gastric surgery with 30 patients operated on by laparoscopic approach are hereby described. The aim of this issue is to provide surgeons with guide lines for progressive training, respectful to patients, complying with oncologic criteria and useful to reduce conversion rate or drawbacks at the start of the experience.
The Authors made a retrospective analysis on 30 patients affected by gastric lesions, 5 benign chronic ulcers and 25 neoplasms of the stomach. Our guide lines suggest that the training begin with the treatment of benign lesions, followed by early gastric cancer (EGC) and by advanced gastric cancer (AGC) of the antrum. Our experience started with 4 laparoscopic subtotal distal gastrectomies (LSGs) for benign ulcer; independent of the guidelines hereby proposed 1 laparoscopic total gastrectomy (LTG) was done after the intraoperative finding of a benign ulcer of the lesser curve penetrating into the left hepatic lobe. The beginning of training included also 1 LSG for distal stromal tumor (GIST). Subsequently 13 early gastric cancers (EGC) were operated on: echoendoscopy could demonstrate 12 T1 m and 1 T1 sm and no evidence of nodal involvement. The diameter of EGCs was 1,3 cm on average ( range 0,7-4 cm), all were marked by Indian ink to allow performance of 10 LSGs and 3 LTGs. Moreover, 8 LSGs for advanced gastric carcinoma (AGC) of the antrum were carried out. The training in malignancies progressed with LTG for 2 non-Hodgkin gastric lymphomas; 1 lymphoma required conversion to laparotomy due to infiltration of the diaphragmatic crus. A D2 lymphadenectomy was associated to gastrectomy in adenocarcinomas.
The feasibility of laparoscopic gastric surgery was confirmed by this study, with operating time of 240 minutes (range 150-360), intraoperative blood loss was 180 ml (range 100-250), and only 1 patient required blood transfusion for postoperative bleeding. The specific morbidity rate was 10% owing to duodenal leakage in 3 cases in the early phase of this study (3/30): 1 required laparotomy. The mortality rate was 3% due to 1 serious postoperative bleeding and acute hepatic failure in a patient with post-alcoholic cirrhosis. The conversion rate was 3% (1/30). The nasogastric tube was removed on the 4(th) postoperative day, and the oral intake started on the 6(th) postoperative day after a barium follow-through examination. The mean postoperative hospital stay was 16 days (range 10-25). The number of nodes retrieved was 18 on average and it improved with the experience: from the minimum of 9 nodes in benign ulcers, it grew to 20 in EGCs and to 25 in AGCs, so that this data confirmed the guide lines proposed in this issue . The histologic examination of EGC confirmed the data of echoendoscopy about nodal status.
Laparoscopic surgery is a safe and feasible procedure both for benign and for malignant lesions of the stomach. The results analysed hereby suggest that at the start of training be treated patients affected by benign lesions, followed by patients with EGC and then by patients with AGC. For gastric cancers, the average number of 18 nodes harvested from each patient was adequate, complying with the requirements suggested by the latest TNM classification. This choice of progressive selection of patients for training represents a good means to get an optimal performance level, especially in view of the oncologic requirements, and can prevent surgeons from elevated conversion rates and disappointing outcomes at the beginning of experience.
The result of using traditional techniques in the treatment of large hernias of the abdominal wall (recurrent inguinal hernia and incisional hernia) are compared with those obtained by using ...prosthetic material. In most cases of incisional hernia the reconstruction was carried out by traditional techniques. Instead, the Authors' preference is for the use of prosthetic material in the treatment of recurrent inguinal hernia.
